The coastal low that four days of products have been pointing at finally has a name in a forecaster's own file, and a new headline to go with it. Overnight, three National Weather Service offices from New Jersey to Cape Cod put storm watches over their offshore waters for Thursday night into Saturday. That is the step above the gale warnings that have been flying since Tuesday morning, and it is the first time this week anyone on the East Coast has used it.

Closer in, the water arrived on schedule. NWS Wakefield's 6:25 a.m. EDT package put coastal flood warnings up for all of Hampton Roads, and the office's 6:45 a.m. forecast discussion said why in one line: moderate flooding was expected with the morning high tide in multiple locations. On the Outer Banks, Hatteras Island and Ocracoke Island go under a warning at 2 p.m. for two to four feet of inundation, the largest number written anywhere on the coast today.

Key points

• Storm watches were issued overnight for offshore waters from Sandy Hook, New Jersey to Massachusetts Bay, covering Thursday evening through Saturday, with gusts to 55 knots and seas to 17 feet listed as possible.
• Coastal flood warnings cover fifteen zones from Ocracoke to the Jersey shore this afternoon and tonight, with two to three feet of inundation written for Hampton Roads and two to four feet for Hatteras and Ocracoke islands.
• Three offices said in writing that the weekend is still uncertain, including how close the low comes and whether it lingers into Sunday.

Yesterday and overnight: rain on the damming wedge

Eastern Virginia spent the night under cold air damming, a wedge of cool air pinned east of the Blue Ridge, with rain falling into it. NWS Wakefield's 3:45 a.m. EDT discussion described a nearly stationary band of rain running from west of Farmville to Cambridge, and reported one gauge total, with its own caveat attached: observations are limited, but a gauge in southwestern Powhatan has recorded 5.36 inches in 3 to 4 hours. That is a single gauge in a forecast discussion, not a verified storm total, and the office said as much.

The same office's marine section put the two pieces of the map in one sentence at 2:55 a.m. EDT: a developing low of about 1011 millibars a couple of hundred miles off the North Carolina coast, and strong high pressure of about 1038 millibars over southern Quebec. The pressure difference between those two is the northeast wind that has been pushing water into the Chesapeake all week.

Well away from any of it, six frost advisories were in effect at dawn across the upper Great Lakes and northern Vermont, from NWS Duluth, Green Bay, Marquette, Gaylord and Burlington. All of them expired between 7 and 9 a.m. local time.

Today, officially: the storm watch

The new product is the storm watch, and it is a marine headline. The watches carry the products' own phrase, storm force winds, and each one is written alongside the gale warning it follows, so the offices are describing a two stage week on the water: gales today and Thursday, potentially worse Friday and Saturday.

Ten storm watches were active nationally at 11:07 a.m. UTC, all ten from those three offices. The only storm warnings in the country were three from NWS Anchorage. Of the 79 gale warnings active at the same minute, 45 were Alaskan, from Anchorage and Juneau, and 34 ran the East Coast from Wilmington, North Carolina to Boston. Source: NWS active alerts, api.weather.gov, read at 11:07 to 11:20 a.m. UTC.

Today, officially: the tide

Fifteen coastal flood warnings were active this morning, from three offices, and they were the only coastal flood warnings in the country.

Inundation figures are the products' own, stated as feet above ground level in low lying areas near shorelines and tidal waterways. Sent times: Wakefield 6:25 a.m., Morehead City 4:48 a.m., Mount Holly 4:28 a.m. EDT.

The impact wording still separates the offices, the way it did last night. Morehead City writes that portions of Highway 12 will be inundated and that low lying property including homes, businesses and some critical infrastructure will be inundated, in the plain future tense. Mount Holly writes that widespread roadway flooding occurs at this level, many roads become impassable, and some damage to vulnerable structures may begin to occur. Wakefield's wind advisory reason, given in the 6:45 a.m. discussion, is that winds will likely gust in excess of 50 mph this afternoon into Thursday night along the immediate coast.

Up the Chesapeake, NWS Baltimore and Washington held its line. At 3:59 a.m. EDT the office wrote that a long duration coastal flood event is expected over the next several days within persistent onshore flow, that overnight changes were small, and that decisions would likely need to be made this morning regarding whether watches are converted to warnings or advisories. As of the 11:07 a.m. UTC wire, that office had five coastal flood advisories and three watches up, at Annapolis, Alexandria, Straits Point, Dahlgren and Solomons Island, and no warnings.

What the offices say they do not know

Three discussions said the weekend is unsettled in the forecasting sense, not the weather sense.

- NWS Boston/Norton, 1:55 a.m. EDT: a strong coastal low pressure system will bring impacts to southern New England in the form of rain, rough seas, strong winds, and coastal flooding or erosion Friday into the weekend. Exact timing and magnitude of the winds and rain remain unknown.

- NWS Upton, 4:04 a.m. EDT: global models in agreement with a coastal low tracking southeast of the area during the Friday to Saturday period, but differences show up regarding how close the center of the storm will be and whether or not it lingers nearby or retrogrades closer into Sunday.

- NWS Wakefield, 6:45 a.m. EDT: confidence in the forecast for this weekend remains below average due to uncertainties with a developing coastal low.

NWS Baltimore and Washington used the word the rest of the week has been circling, in its second key message at 3:59 a.m. EDT: breezy and warmer this weekend, but forecast remains uncertain as Nor'easter impacts Northeast U.S.

Elsewhere

The Storm Prediction Center's day 1 outlook carried a Marginal Risk as its highest category, with thunderstorms and isolated severe wind gusts and hail possible this afternoon across parts of the southern Appalachians. Two flash flood warnings were issued overnight by NWS El Paso for Dona Ana and Otero counties in New Mexico and El Paso County, Texas, both expiring before 6 a.m. MDT. The National Hurricane Center's 09:00 UTC advisories carried Hurricane Odalys at 65 knots, Hurricane Polo at 135 knots and Tropical Depression Fifteen-E at 30 knots, all in the eastern and central Pacific, with no watches or warnings for the United States.

Two products this brief would normally check were unavailable to us again this morning. The Storm Prediction Center's preliminary storm reports for yesterday and the Weather Prediction Center's day 1 excessive rainfall outlook both returned HTTP 403 to our wire tool, the tenth straight day. Their absence from this brief is our reach, not their silence.

This is a summary of official warnings, not emergency information. For live warnings see weather.gov and your local officials.

The rock's live forecast for the places in this story

• Norfolk VA
• Virginia Beach VA
• Hampton VA
• Portsmouth VA
• Chesapeake VA
• Newport News VA
• Ocracoke NC
• Buxton NC
• Cape May NJ
• Nantucket MA
• Annapolis MD
• Alexandria VA

Key points

• The Central Pacific Hurricane Center's 5 a.m. Hawaii time advisory has Tropical Depression Fifteen-E about 320 miles south-southeast of South Point, and forecasts it to approach the Big Island on Friday and Saturday as a hurricane.
• The same advisory calls for 15 to 20 inches of rain on the Big Island with maximum amounts near 35 inches, and says a hurricane or tropical storm watch will likely be required for part of the state later today.
• On the other side of the country the coastal low's fourth day brought the Baltimore and Washington office into the coastal flood warning list at 3:08 p.m. Eastern, the first time it has held one this week.

Hawaii, and a depression the forecasters are not treating as a depression

The system south of Hawaii is a tropical depression with 35 mph winds, which is the weakest thing the hurricane center names. Almost nothing else about the products written for it this morning reads that way.

At 5 a.m. Hawaii time the Central Pacific Hurricane Center put the center of Tropical Depression Fifteen-E at 14.5 North, 154.4 West, about 320 miles south-southeast of South Point on the Big Island, drifting west-northwest at 6 mph. The advisory, number 12, was issued out of the National Hurricane Center in Miami. It says the depression is expected to become a tropical storm later today, a hurricane on Thursday, and possibly a major hurricane by the weekend, and that on the forecast track it approaches the Big Island on Friday and Saturday. The watches and warnings section carries no product yet. What it carries instead is a sentence: a hurricane or tropical storm watch will likely be required for a portion of the state later today.

The rainfall numbers are the part worth reading twice. The advisory forecasts 15 to 20 inches across the Big Island with maximum amounts of 35 inches, and says that rain may produce catastrophic life threatening flooding and mudslides, especially in areas of steep terrain. Maui is given 5 to 10 inches with maximum amounts of 20. The rest of the islands are given 1 to 3 inches.

The forecaster on duty, Blake, wrote the uncertainty down rather than around. The discussion issued at the same hour says the low level circulation is not well aligned with the deep convection yet, that satellite intensity estimates spread from 25 to 40 knots, and that a trough is expected to force a sharp westward turn while the cyclone is close to the Big Island. Of that turn it says plainly that it is impossible to know exactly when it will happen, and that there is a large north to south spread in the guidance. The forecast was raised anyway, because the best performing aids showed a major hurricane, and the environment ahead of the storm has low shear and sea surface temperatures of 28 to 29 degrees Celsius.

The Honolulu forecast office put a flood watch up at 3:44 a.m. Hawaii time, in effect from noon today through Saturday afternoon, covering the Big Island, Maui, Lanai, Molokai and Kahoolawe. Its own morning discussion, written at 4:15 a.m., says the depression redeveloped overnight just over 400 miles south-southeast of Hilo, that windward Big Island collected roughly a quarter to a half inch of rain overnight, and that the office expects the system to be at hurricane strength when significant impacts could begin on Friday. It also names what the advisory had not yet: the office wrote that the latest forecast calls for Fifteen-E to intensify into Tropical Storm Nolo.

Tropical Depression Fifteen-E, advisory 12

The forecast track, as issued

Forecast rainfall, by island group

Source: Central Pacific Hurricane Center public advisory 12 and forecast discussion 12 for Tropical Depression Fifteen-E, both issued 5 a.m. HST September 23, and the NWS Honolulu area forecast discussion issued 4:15 a.m. HST September 23. Positions and winds are the forecast as issued, not an observation.

The East Coast low, day four

The coastal low that has been running this week's coverage kept its ladder climbing on Wednesday afternoon. At 3:08 p.m. Eastern the Baltimore and Washington office issued coastal flood warnings for the Anne Arundel and St. Marys shorelines, its first of the week. That office held three watches and no warnings when the wire ran this morning, and its own morning discussion said the conversion decision was still to be made.

The Anne Arundel product gives up to one foot of inundation above ground level from 11 p.m. tonight to 11 a.m. Friday, and names the stage at which it starts: at 3.2 feet, water begins to approach businesses on Dock Street in Annapolis, the City Dock parking lot is flooded, and Compromise Street is flooded. The St. Marys product runs from 9 p.m. tonight to 5 p.m. Friday, with water covering roads on Saint George Island at 3.5 feet. The stages are printed with no datum, so they are copied here as written.

The largest numbers on the coast are still south of that. The Newport and Morehead City office, in a product sent at 4:48 a.m. Eastern, forecasts 2 to 4 feet of inundation for Hatteras Island and Ocracoke Island from 2 p.m. Wednesday to 11 p.m. Friday, and writes that portions of Highway 12 will be inundated and that some critical infrastructure will be inundated. Storm watches for Thursday evening through Saturday were still standing over the New England and New York waters, unchanged in number and in office since this morning.

Coastal flood warnings active at 3:15 p.m. Eastern, by office

Other coastal products on the same stretch

Source: NWS active alerts read at 19:15 UTC September 23. Counts are of individual products, not of counties.

Inland, an afternoon of small warnings

Away from both coasts the afternoon belonged to short flash flood warnings over saturated ground. The Charleston, West Virginia office issued four of them between 2:04 and 3:09 p.m. Eastern. The 2:04 p.m. extension for northwestern Boone and east central Lincoln counties reported 3 to 5 inches of rain already fallen, used the wording life threatening flash flooding, and named Route 119 between mile markers 54 and 58. The 3:09 p.m. warning for parts of Roane, Calhoun and Gilmer counties listed Chloe, Orma, Nicut and Tariff. All four gave radar as their source, which is a lower bar than a ground report.

The Peachtree City office issued one at 3:02 p.m. Eastern for northwestern Gilmer and east central Murray counties in north Georgia, with 2 to 3 inches fallen and Fort Mountain State Park named as a location that will experience flooding.

Behind the warnings sat a wide field of watches. The Charleston office's flood watch, issued at 11:07 a.m. Eastern, runs until 10 p.m. across nine West Virginia counties plus Lawrence County in Kentucky and Buchanan and Dickenson counties in Virginia, and says the showers are moving slowly over soils compromised from recent rainfall. The Jackson, Kentucky office watch covers twenty counties until 10 p.m. In the Southwest, Albuquerque, Midland, El Paso, Amarillo, Grand Junction and Pueblo all carried flood watches running into Thursday night and, in the Texas and Oklahoma panhandles, Friday morning.

Flash flood warnings issued Wednesday afternoon

Source: NWS active alerts read at 19:15 UTC September 23. Rainfall figures are the radar estimates quoted inside each product.

One instrument note

The Storm Prediction Center's preliminary storm reports for yesterday and the Weather Prediction Center's day one excessive rainfall outlook both returned an HTTP 403 to the house wire tool again today, as they have every day since September 19. So this brief carries no yesterday report count. That is a gap in our reading, not a quiet day on the record.

Where the official guidance lives

For anyone in Hawaii reading this days ahead of the storm, the federal preparedness guidance is at ready.gov, the flood page at ready.gov/floods, and the National Weather Service's own flood safety page at weather.gov/safety/flood. Those are guidance pages, not aid applications, and nothing on them is quoted here.

This is a summary of official warnings, not emergency information. For live warnings see weather.gov and your local officials.

The rock's live forecast for the places in this story

• Hilo HI
• Kailua-Kona HI
• Kahului HI
• Honolulu HI
• Annapolis MD
• Hatteras NC
• Ocracoke NC
• Hamlin WV

Key points

• The Central Pacific Hurricane Center's 5 a.m. Hawaii time advisory has Tropical Depression Fifteen-E forecast to approach the Big Island on Friday and Saturday as a hurricane, and NWS Honolulu put a flood watch up at 3:44 a.m. Hawaii time for the eastern islands.
• This page is the list of official doors to ask for help, in the order they are usually useful, and nothing on it is a figure of ours.
• Hawaii, West Virginia, Kentucky, Virginia, Georgia, Maryland and North Carolina have no state emergency management entry on the rock's standing verified list, so no state link is printed here.

Why this list, today

The rock's afternoon story is [the Big Island approach](/journal/beat/hawaii-fifteen-e-big-island-hurricane-approach-2026-09-23/). It carries the products and the numbers. This is its sister page, and it carries no weather numbers at all. It is only the list of places to ask.

Three groups of people are reading today. In Hawaii, the Honolulu forecast office's flood watch issued at 3:44 a.m. Hawaii time runs from noon today through Saturday afternoon over the Big Island, Maui, Lanai, Molokai and Kahoolawe, ahead of a system the 5 a.m. advisory forecasts to arrive as a hurricane. On the mid-Atlantic coast, the week's coastal low has coastal flood warnings out at five forecast offices, including the Chesapeake shoreline at Annapolis and, with the largest numbers on the coast, Hatteras and Ocracoke. Inland, NWS Charleston in West Virginia and NWS Peachtree City in Georgia issued flash flood warnings through Wednesday afternoon over ground that had already taken rain.

If you are in any of those places, the list below is where the official help is asked for. If you are not, it keeps for the next time.

Where to ask

Apply for federal disaster aid. The federal front door. It asks for an address and tells you what federal help is available there, which is also how you learn whether your county has been declared.

211. Local referrals for any need, by call or text. The page says to call 211 and to find your local 211. No other number is on it, so no other number is quoted here.

American Red Cross, Get Help. Shelters and emergency assistance. The page has a link to find an open shelter and a link to contact your local Red Cross.

The Salvation Army. The organisation's national page. We link the root only, because its dedicated disaster address does not stay up, and a link that does not open is not a resource.

SBA disaster loans. Disaster loans for homeowners and renters as well as businesses, which is the part people miss.

Ready.gov and its flood page. Federal preparedness guidance, which is the part of this list that is useful before a storm rather than after one.

NWS flood safety. The National Weather Service's own flood safety page.

One honest note about what is missing. We do not link the FEMA disaster declarations page, because it does not open for us: it serves a bot check instead of the declarations list. The question it would answer, whether your address is covered and what you can apply for, is answered at disasterassistance.gov above.

Every link here comes from the rock's standing verified aid list. Nothing was discovered at press time, and no county office, charity or news site appears, because that is exactly how people get sent to the wrong place after a storm.

This is a summary of where to ask, not emergency information. For live warnings see weather.gov and your local officials.

The rock's live forecast for the places in this story

• Hilo HI
• Kailua-Kona HI
• Kahului HI
• Honolulu HI
• Annapolis MD
• Hatteras NC
• Ocracoke NC

Key points

• Four National Weather Service offices posted Frost Advisories for tonight across Vermont, northern New York, Maine and New Hampshire, the earliest at 12:59 p.m. EDT and the latest at 2:16 p.m. EDT.
• The cold is not a front. Three of the four offices name the same cause in their afternoon discussions: high pressure over Quebec, very dry air, clear sky and light wind.
• The advisories do not cover the coldest ground. NWS Caribou expects northern Maine to reach freezing or below and has issued no advisory there, because an advisory follows the growing season rather than the thermometer.

Wednesday afternoon, and why tonight is cold

Nobody sent this one. There is no storm in it, no front arriving, nothing on radar. Between 12:59 and 2:16 this afternoon, four weather offices looked at a clear sky and a dry airmass and decided that tonight is the night to tell gardeners to cover things up.

NWS Caribou went first, at 12:59 p.m. EDT, and its 2:06 p.m. discussion says plainly what is sitting over the region: "Surface 1040mb high pressure is centered over Quebec this afternoon, with upper level high pressure building into the region from Ontario." That is the whole mechanism. High pressure means sinking, drying air, which means no cloud, and no cloud on a long September night means the ground radiates its heat away to space with nothing to send it back.

NWS Burlington put a number on the drying at 2:24 p.m. EDT: "PWats across the area are dropping to 0.2-0.4 inches, resulting in dewpoints in the upper 30s for most of the area. These lower dewpoints will set up our cooling potential tonight with another round of clear skies and strong radiational cooling expected."

Note the words "another round." This is not the first frost of the season in either state, and none of the four offices say it is. NWS Gray calls tonight "Another radiational cooling night," and its own advisory covers hillier interior terrain that was not covered last night.

Source: the four Frost Advisory products active at 7:30 p.m. EDT, quoted from their own WHAT and WHEN blocks. Two of the four carry a machine expiry time earlier than the end of their own stated window, which is normal product bookkeeping and not a change to the forecast.

The line the advisories drew is a calendar, not a temperature

The interesting thing about tonight is where the advisories stop.

NWS Albany said it in one sentence at 2:34 p.m. EDT: "Where the growing season in still in effect, a Frost Advisory has been issued for S. Warren and Washington Counties from 2 AM to 9 AM Thursday." The office expects lows "from the mid 30s in the ADKs into the Glens Falls/Lake George area to lower 40s in the Hudson Valley south of Albany," and only two counties carry the advisory. The rest of the forecast area will be just as cold. It is simply past the point in the year where a frost there would cost anybody a garden.

Maine shows the same logic at a larger size. NWS Caribou's discussion says "Northern areas of Maine will likely reach freezing or below freezing," and the only Frost Advisory that office issued is for southern Penobscot County, at the warm end of its own forecast. The coldest ground in the state tonight is not under an advisory, and that is correct.

NWS Burlington marks the opposite edge of the same idea. Its advisory carries an ADDITIONAL DETAILS line saying "Areas near and along Lake Champlain, generally within 5 miles, will be less likely to see frost," because a big lake in September is still holding summer's heat. The same discussion expects "Pocket mid to upper 20s" in isolated parts of the northern Adirondacks.

So the map tonight is drawn by three things at once: how cold it gets, what is still growing, and how close you are to water.

Tonight and Thursday, officially

All four products carry identical impact and instruction language: "Frost could harm sensitive outdoor vegetation. Sensitive outdoor plants may be killed if left uncovered," and "Take steps now to protect tender plants from the cold."

NWS Gray expects the high to hold through Thursday, "keeping a seasonably cool and dry airmass in place," with sunny skies and highs in the 60s. NWS Caribou expects a second, patchier round of frost and river valley fog Thursday night, mainly in the north, as cloud increases from the south.

That increasing cloud is the other half of this week. The same NWS Gray discussion reports "No significant changes regarding the possible impacts from the coastal low this weekend, but rain chances have continued to increase," and the office already carries Gale Watches for its coastal waters from Friday afternoon through Sunday evening. The clear night that is making tonight cold is being delivered by the last of the quiet weather.

This is a summary of official warnings, not emergency information. For live warnings see weather.gov and your local officials.

The rock's live forecast for the places in this story

• Burlington VT
• Rutland VT
• Bangor ME
• Glens Falls NY
• Lake George NY

Key points

• The National Weather Service office in Honolulu issued a Hurricane Watch for Hawaii County at 11:01 a.m. Hawaii time, covering the whole of the Big Island and its surrounding waters.
• The system it was written for became Tropical Storm Nolo on the 11 a.m. advisory cycle, and the 2 p.m. Hawaii time intermediate advisory put it 305 miles south of South Point with 45 mph winds, forecast to be a hurricane on Thursday.
• In Appalachia the afternoon's radar-only flash flood warnings turned into ground reports after dark: law enforcement reported flooded roads in Boone and Lincoln counties in West Virginia at 7:18 p.m. Eastern, and the public reported flooding at Pilgrim, Kentucky at 7:29.

The watch the morning advisory said would probably be needed

This afternoon the rock wrote that the Central Pacific Hurricane Center expected a watch would likely be required for part of Hawaii later in the day. It was required. At 11:01 a.m. Hawaii time the Honolulu forecast office issued a Hurricane Watch for Hawaii County, and at 11:03 it issued one for the Big Island waters and the Alenuihaha Channel. The 2 p.m. advisory carries it at the top of the bulletin.

A Hurricane Watch is not a forecast that a hurricane will arrive. The product says what it means in its own first line: hurricane-force winds are possible somewhere within the area within the next 48 hours. It is typically issued 48 hours before the first tropical-storm-force winds, because that is the point at which work outdoors becomes difficult or dangerous. The watch is a clock, not a verdict.

The storm also has a name now. Discussion number 13, written at 11 a.m. Hawaii time by forecaster Blake, set the initial intensity at 35 knots and recorded that this marked the formation of a tropical storm. By the 2 p.m. intermediate advisory, issued by forecaster Gibbs, Nolo was at 45 mph and 1002 mb, moving west at 9 mph, with tropical-storm-force winds reaching only 35 miles from the centre. It is still a small, lopsided system. The advisory expects it to be a hurricane on Thursday and says it could be a major hurricane by the weekend.

What the forecasters keep saying, in both documents, is that they do not know the track. The discussion puts the north-to-south spread in the guidance at close to 250 nautical miles by the weekend, says the new forecast was nudged south, and then adds the sentence that matters: it should be considered low confidence. The turn depends on how far northeast Nolo gets before a ridge rebuilds north of Hawaii, and the solutions that gain the most latitude are the ones that come closest to the island.

One small thing in the Honolulu discussion says as much about the day as any number. The office wrote that it is moving its own schedule: products that normally appear between 3 and 4 in the afternoon or morning will now be issued at or shortly after 5, to line up with the hurricane center's updates. A forecast office changing its clock is what preparation looks like from the inside.

Tropical Storm Nolo, intermediate advisory 13A, 2 p.m. HST September 23

The forecast track as issued, discussion 13, 11 a.m. HST

Source: Central Pacific Hurricane Center intermediate advisory 13A, issued 2 p.m. HST September 23, and tropical cyclone discussion 13, issued 11 a.m. HST September 23, both under the storm number EP152026. Positions and winds beyond the first row are the forecast as issued, not observations.

What the watch says town by town

The zone products behind the watch are more specific than the advisory, and they separate two numbers that are easy to run together. The first is the current local forecast for peak wind. The second is the threat if the track and the intensity go wrong in the ordinary ways they go wrong, which the products label as including typical forecast uncertainty. For most of the Big Island the first number is a tropical storm and the second is a category 1 or 2 hurricane.

The highest ground has the highest numbers and the earliest clock. For the summits of Mauna Kea and Mauna Loa the forecast peak wind is 55 to 75 mph with gusts to 110, and the product gives a window for hurricane-force winds from Friday evening until early Saturday morning. Hilo, Pahoa and Volcano are at the gentle end, 25 to 35 mph with gusts to 50. Kailua-Kona is gentler still. Every one of those zones carries the same storm surge line, 1 to 3 feet above ground in surge-prone areas, with the window opening early Friday morning.

The rainfall is unchanged from this morning and is still the part of this storm that reads worst. The advisory forecasts 15 to 20 inches across the Big Island with maximum amounts of 35 inches, and says it may produce catastrophic life-threatening flooding and mudslides, especially in steep terrain. Maui is given 5 to 10 inches with maximum amounts of 20.

The Hurricane Watch zones, peak wind as forecast at 11:01 a.m. HST

Source: the Hurricane Watch zone products issued by NWS Honolulu at 11:01 a.m. HST September 23. Peak wind is each product's own latest local forecast line, not the separate threat figure the same product gives for the uncertainty case.

Appalachia, after dark, with witnesses

The rock's afternoon brief made a point of noting that every flash flood warning in West Virginia that day gave radar as its source, which is a lower bar than a ground report. The evening supplied the ground reports.

At 7:18 p.m. Eastern the Charleston office warned northwestern Boone and northeastern Lincoln counties on the strength of local law enforcement reporting flooded roadways, with 3 to 6.5 inches of rain fallen and 1 to 2 more possible. That is the largest rainfall figure any product carried in that state today. At 7:29 p.m. the Jackson, Kentucky office warned Martin County because the public reported flash flooding at Pilgrim. At 6:47 p.m. the same office had extended a warning over Bell and Harlan counties after the public reported flooding at Ages, Cubage Hill and Brownies Creek.

The line kept working east and south through the evening, into Knox County, Tennessee at 6:29 p.m., and back over Clay, Knox and Bell counties in Kentucky at 8:03 and 8:10. Fifteen flash flood warnings were active across five offices when the wire ran at 00:15 UTC.

Arizona had its own version. At 5:15 p.m. Mountain Standard Time the Flagstaff office warned part of Yavapai County because a river gauge on the Agua Fria reported a rise of 3.3 feet, with 1 to 2 inches of rain fallen and no more expected. A gauge rise is the least arguable source there is.

Flash flood warnings issued Wednesday evening, with their sources

Source: NWS active alerts read at 00:15 UTC September 24. Rainfall figures are the estimates printed inside each product.

One instrument note

The Storm Prediction Center's preliminary reports for yesterday and the Weather Prediction Center's day one excessive rainfall outlook both returned an HTTP 403 to the house wire tool again tonight, the fifth straight day. The Storm Prediction Center's day one outlook did come through, with a marginal risk for parts of the western Dakotas. The missing pieces are a hole in our reading, not a quiet day on the record.

Where the official guidance lives

Federal preparedness guidance is at ready.gov and its flood page, and the National Weather Service's flood safety page is at weather.gov. The rock published a full list of the official doors to ask for help earlier today, and it is linked below.

This is a summary of official warnings, not emergency information. For live warnings see weather.gov and your local officials.

The rock's live forecast for the places in this story

• Hilo HI
• Kailua-Kona HI
• Kahului HI
• Honolulu HI
• Hamlin WV

Key points

• Six National Weather Service offices from Morehead City, North Carolina to Boston upgraded yesterday's gale watches to gale warnings before 7 o'clock this morning, for a coastal low their forecasters expect to form off the Carolinas today.
• Coastal flood advisories are in effect along the Virginia and Delaware coasts for tonight's high tides, with up to a foot of water expected above ground level in low places, and watches carry one to three feet as possible Wednesday and Thursday.
• The first land product of the week went out at 2:51 this morning: a wind advisory for the New Jersey and Delaware beach strip for Wednesday, northeast at 25 to 35 miles an hour with gusts near 45.

Yesterday

The front that came through the mid-Atlantic on Sunday night stalled and sat. In the Carolinas it gave the kind of rain that falls all at once in one place and nowhere else: the Wakefield office wrote this morning that a couple of efficient storms along the Virginia and North Carolina border last evening dropped two to three inches in a short period, enough to lift the Cashie River at Windsor more than a foot. That is the whole of yesterday's damage report as the products tell it. The Storm Prediction Center's page of preliminary reports would normally settle the rest, and it refused our request again today, the seventh morning running, so this brief cannot say what was reported elsewhere.

Further south the same stalled boundary was still working this morning. NWS Peachtree City issued two flash flood warnings in the north Georgia mountains before 6:31 a.m. EDT, one for Gilmer, Gordon and Murray counties and one for Dawson, Fannin, Gilmer and Pickens, both written to run out around midday.

Today, officially

The story of this week is a low that did not exist when we wrote about it yesterday. Yesterday it was a forecast inside four marine watches. This morning three offices independently wrote down that it is coming.

NWS Mount Holly put it plainly at 7:17 a.m. EDT: gale watches upgraded to gale warnings for all coastal waters, and a wind advisory issued for Atlantic coastal New Jersey and Delaware. NWS Newport and Morehead City, whose discussion went out at 3:30 a.m. EDT, had converted its watches to warnings too and started the headlines six to twelve hours earlier than planned because the wind is now expected sooner. NWS Wakefield at 6:31 a.m. EDT listed gale warnings, high surf advisories and what it called ramp-up coastal flood advisories. Morehead City's forecasters expect a low below 1000 millibars to deepen offshore tonight into Wednesday, and they expect it to be slow. Their own words for it: the low will meander about off the mid-Atlantic coast through late in the week, which is why the wind lasts for days rather than hours.

At 11:42 this morning there were 34 gale warnings active in the country. Thirty-three of them were on the East Coast, spread across Wakefield, Boston, Morehead City, Mount Holly, Upton and Baltimore. The thirty-fourth was off northern California. Yesterday morning every active gale warning in the United States was in Alaska.

On land it arrives as water in the usual low places first. Wakefield's 6:28 a.m. EDT package puts coastal flood advisories on Norfolk, Portsmouth, Chesapeake, Suffolk, Hampton, Poquoson and Virginia Beach from four this afternoon, on the Northern Neck from ten this morning, and on the Maryland beaches, Accomack and Northampton from four, all of them for up to one foot of inundation above ground level. Mount Holly's 4:42 a.m. EDT advisory covers the Delaware beaches and the Ocean, Atlantic and Cape May county coasts from four this afternoon to ten tonight, the same one foot. The bigger numbers sit in the watches behind them, for Wednesday and Thursday: one to three feet possible around Hampton Roads and the tidal rivers, two to three feet possible at Virginia Beach and across Surry, James City, Newport News and Isle of Wight. Morehead City issued its own watch at 4 a.m. EDT for the northern Outer Banks, Hatteras Island and Ocracoke Island, two to three feet possible from Wednesday afternoon through Friday evening.

Wakefield's third key message this morning is the one sentence that says what the office actually thinks is going to happen, and it is worth reading whole: "Widespread moderate to locally major tidal flooding (inundation of 2-3 feet AGL in vulnerable areas) is likely by the Wednesday afternoon/evening high tide due to strong northeast winds. Tidal flooding is expected to continue for several tide cycles given the persistent northeast winds."

There were no coastal flood warnings anywhere in the country this morning. The ladder still stops one rung short.

The end of the week is genuinely unsettled, and the forecasters say so. Mount Holly's discussion describes the models as falling into two relatively distinct camps after Friday, one taking the low away to the northeast and one turning it back toward the coast, and the office notes the difference in outcomes between the two is substantial. That is why the products past Thursday are watches and probabilities rather than warnings.

A cooler note underneath all of it: highs today in the Philadelphia area were forecast for the upper 50s and 60s, and Wakefield expects its coolest day of the week on Wednesday, low to mid 60s inland. Frost advisories were posted this morning by five northern offices, from Grand Forks across Duluth, Green Bay, Marquette and Gaylord, with a freeze warning in Michigan's Upper Peninsula. The season is turning in the north while the coast gets its wind.

The marine vitals, 11:42Z 2026-09-22

Source: National Weather Service marine products active at 11:42Z on 2026-09-22, quoted from each product's own WHAT and WHEN blocks.

The land products

The Storm Prediction Center's 6 a.m. outlook carries a Marginal risk, its lowest category, for isolated severe wind gusts in parts of the Southeast and near north-central and northeastern Utah. Three named storms were on the National Hurricane Center's board this morning, Fay and Odalys as tropical storms and Polo as a hurricane in the eastern Pacific, none of them with a United States watch or warning attached.

This is a summary of official warnings, not emergency information. For live warnings see weather.gov and your local officials.

The rock's live forecast for the places in this story

• Buxton NC
• Ocracoke NC
• Norfolk VA
• Virginia Beach VA
• Hampton VA
• Chincoteague VA
• Ocean City MD
• Cape May NJ
• Nantucket MA

Key points

• Three National Weather Service offices were carrying coastal flood warnings as of this evening, sixteen zones in all, from Ocracoke Island to the New Jersey shore, and they are the only coastal flood warnings active in the country.
• The largest number on the wire belongs to the Outer Banks. NWS Newport/Morehead City's 4:42 p.m. EDT product puts 2 to 4 feet of inundation above ground level on Hatteras Island and Ocracoke Island, and says portions of Highway 12 will be inundated.
• None of it begins tonight. The earliest warning starts at 5 a.m. Wednesday and the last one runs to 11 p.m. Friday, because the forecasters expect several tide cycles of northeast wind rather than one bad high tide.

What changed this afternoon

This morning the story was marine. Six East Coast offices had turned gale watches into gale warnings before 7 a.m., for a low that had not formed yet. By late afternoon the same system had produced land products in three states, and the belt of coastal flood warnings had grown from one office to three.

NWS Wakefield went first, at 2:57 p.m. EDT, with ten warnings covering Hampton Roads, the Middle Peninsula, the Eastern Shore and the lower Maryland shore. Its own discussion, written at 3:49 p.m., says plainly what it did: all coastal flood watches have been upgraded to coastal flood warnings. NWS Mount Holly followed at 4:14 p.m. for the Delaware beaches, Kent and inland Sussex counties, Cape May, Atlantic and Ocean counties in New Jersey, and southeastern Burlington. NWS Newport/Morehead City came last, at 4:42 p.m., with two products for Hatteras Island and Ocracoke Island.

Coming last does not mean coming smallest. The Outer Banks products carry the highest figure of the sixteen, 2 to 4 feet of inundation above ground level expected, and the same office adds up to a foot of sound side flooding from Buxton southward late Thursday and Friday, when it expects the wind to turn more northerly.

There is one other difference worth reading closely, because it is the only place these otherwise identical products disagree about certainty. Wakefield and Mount Holly both write that low lying property including homes, businesses and some critical infrastructure may be inundated. Morehead City writes will.

The sixteen coastal flood warnings

Inundation is measured above ground level in low lying areas near shorelines and tidal waterways, which is the wording every one of these products uses. Sixteen coastal flood warnings, three offices, sent between 2:57 and 4:42 p.m. EDT today. All times Eastern. Source: NWS coastal flood warning products, read from the active alert feed at 23:21Z, which showed no other coastal flood warning anywhere in the United States.

Why it lasts into Friday

The offices do not describe a single flooding tide. They describe wind holding water against the coast for days.

Wakefield's third key message, written at 3:15 p.m. EDT, reads: "Widespread moderate to locally major tidal flooding (inundation of 2-3 feet AGL in vulnerable areas) is likely by the Wednesday afternoon/evening high tide due to strong northeast winds. Tidal flooding is expected to continue for several tide cycles given the persistent northeast winds."

That is the mechanism, and it is why the warnings do not share one start time. Water arrives at Newport News at 6 a.m. Wednesday and at Ocracoke at 2 p.m., and a single headline time for the whole coast would be a tidier sentence than the weather deserves.

The low itself is still being assembled. Morehead City's 4:20 p.m. EDT discussion expects a consolidation of surface lows off the East Coast over roughly the next day, then rapid deepening later Wednesday into Thursday, with the marine section putting the central pressure as low as around 990 millibars. The same office is candid about what it does not know: guidance has trended west and deeper, some of it slower, and the office writes that not all guidance shows the westward shift and it will keep watching. Mount Holly's 7:07 p.m. EDT discussion frames the whole week in one line, multiple rounds of significant tidal flooding expected, and adds that significant beach erosion is also likely at the Jersey shore and the Delaware beaches.

The wind has a land number too, which no coastal flood product carries. Wakefield added wind advisories for the immediate coast this afternoon because it expects gusts in excess of 50 mph from Wednesday afternoon into Thursday night.

Today, before the tide

The same office that spent the afternoon writing tidal flood warnings spent the earlier part of it on rain. Wakefield's 3:49 p.m. EDT discussion notes showers and storms developing along a stalled boundary across the southeastern part of its area, roughly along the Virginia and North Carolina border, producing locally heavy rainfall and flash flooding. Two kinds of water, the same streets, six hours apart, from two entirely different causes.

Elsewhere on the wire

The tropics are busy and none of it is pointed at the United States. The active alert list carried 539 National Weather Service products at 23:21Z and not one tropical storm or hurricane watch or warning among them.

Source: National Hurricane Center current storms file, advisories issued 21:00Z today. Polo is far off southwestern Mexico and Fay is closer to the Azores than to anything American.

The Storm Prediction Center's day one outlook, in text, put the highest risk category at marginal, for isolated severe wind gusts in Utah into southwest Wyoming and western Colorado and strong to locally severe gusts in parts of the Southeast. Yesterday's preliminary storm reports and the Weather Prediction Center's day one excessive rainfall page both returned an HTTP 403 error to our wire reader again today, the ninth day running, so this brief cannot tell you what yesterday's storm reports held. That is a gap in our reading, not a quiet day on record.

This is a summary of official warnings, not emergency information. For live warnings see weather.gov and your local officials. The coastal flood warning definitions are on the NWS page for flood watches and warnings.

The rock's live forecast for the places in this story

• Buxton NC
• Ocracoke NC
• Norfolk VA
• Virginia Beach VA
• Newport News VA
• Hampton VA
• Poquoson VA
• Portsmouth VA
• Chesapeake VA
• Suffolk VA
• Yorktown VA
• Hopewell VA
• Petersburg VA
• Cape May NJ
• Ocean City MD

Key points

• At 2:53 p.m. EDT Tuesday, NWS Baltimore MD/Washington DC posted five coastal flood advisories and three coastal flood watches, its first of this event, for Anne Arundel, Calvert, Charles, King George, St. Marys, Arlington and the City of Alexandria.
• The office states the water in feet of inundation above ground level: up to one foot on the Calvert shoreline, around one and a half feet at Anne Arundel and Alexandria, two to two and a half feet in St. Marys, and two to three feet along the Charles and King George shore until 2 a.m. EDT Friday.
• Its 7:36 p.m. EDT discussion gives the reason as persistent onshore flow and high astronomical tides near a full moon, and says the office expects some of those watches to become warnings later tonight or early Wednesday.

Yesterday and today: the water went up the bay

For two days this desk has written about the same coastal low from the ocean side, where the gale warnings and the coastal flood warnings are. Tuesday afternoon the story moved inland, up the Chesapeake and up the Potomac, and it arrived at the towns that keep their tide tables on the wall.

NWS Baltimore MD/Washington DC sent eight coastal products in one package at 2:53 p.m. EDT. That office had none of either earlier in the day. The numbers it wrote are small next to the two to four feet the Outer Banks products carry, and they are aimed at places where a foot and a half of water is a known quantity with a known address.

What makes these products worth reading is that they do not talk about a hazard class. They talk about a stage and what is under water at that stage. At 3.5 feet, the office writes, water reaches the floor of the Maritime Museum in Annapolis, begins to cover Bowyer Road on the Naval Academy campus, and floods numerous businesses on Dock Street along with the City Dock parking lot. At 3.0 feet it expects water in backyards near 9th Street in North Beach. At 3.5 feet in St. Marys it puts water over roads on Saint George Island and into marinas. In Alexandria it says water is expected to approach the curb near King Street and Strand Street. The stage numbers are printed without a datum, so they are copied here exactly as the office wrote them.

The timing is not one high tide. The advisories run to different hours by county, the longest to 2 a.m. EDT Friday at Charles and King George, and the watches that follow them run into Friday morning and Friday midday. The office explains why in its evening discussion: "Water levels will continue to rise through at least Thursday due to persistent onshore flow and high astronomical tides from a near Full Moon cycle." It adds that the watches have been extended in time and one is new for the City of Alexandria, "due to the expected long duration event of coastal flooding," and then the sentence a reader should keep: "Expect some watches to be converted to warnings later tonight or early Wednesday morning."

Away from the water, the same office's first key message is about a different kind of week. "Damp and dreary conditions continue through Wednesday afternoon with drier weather returning Thursday," it reads, with a stalled boundary on the Virginia and North Carolina border sending showers north in ripples. One storm, two ordinary things.

The upper bay and the Potomac, as issued

All eight products sent 2:53 p.m. EDT 22 September 2026 by NWS Baltimore MD/Washington DC.

Tides two to two and a half feet above normal across the package, and up to three feet above normal in St. Marys.

Next high tides, by station, as printed in the products

Times as stated in the coastal flood products, Eastern Daylight Time.

The rest of the country, officially

As of the wire run at 1:37 a.m. UTC Wednesday, 449 alerts were active nationwide. Sixteen coastal flood warnings were in force, all of them on the mid-Atlantic and Outer Banks coast from three offices, and they have not grown since last evening. Twenty-four coastal flood advisories were active from four offices, of which five are the new Baltimore Washington set. Four coastal flood watches were active from two offices, three of them Baltimore Washington and one Anchorage.

The Storm Prediction Center's day one outlook states that no severe threat is forecast across the continental United States through daybreak Wednesday. Four flash flood warnings were active, in Colorado, Arizona and New Mexico, none of them connected to this storm. The National Hurricane Center carried three systems, Fay in the open Atlantic at 30 knots, Odalys at 60 knots and Polo at 150 knots in the eastern Pacific, and none of the three carries a United States watch or warning.

Two products this desk normally reads were unavailable again. The Storm Prediction Center's preliminary storm reports for yesterday and the Weather Prediction Center's day one excessive rainfall page both returned HTTP 403 to our wire tool, the tenth day running. That silence is a tool problem on this end and should not be read as a quiet night anywhere.

This is a summary of official warnings, not emergency information. For live warnings see weather.gov and your local officials.

The rock's live forecast for the places in this story

• Annapolis MD
• Alexandria VA
• Solomons MD
• North Beach MD
• Arlington VA
• Dahlgren VA

Key points

• NWS Mount Holly issued the first coastal flood headlines of the week at 1:24 p.m. EDT today: a Coastal Flood Advisory for Tuesday evening's high tide in southern New Jersey and Delaware, and a Coastal Flood Watch for Wednesday afternoon through late Thursday night.
• Six weather offices now hold gale watches, covering water from Nantucket, Massachusetts down to Cape Hatteras, North Carolina, and inside the Chesapeake, Delaware Bay and Albemarle Sound.
• The low all of this is for does not exist yet. The Mount Holly discussion at 2:04 p.m. EDT says a closed mid-level low leaving the Ohio Valley should spin up a surface low off the Eastern Seaboard in midweek, and calls it deep and intense.

A forecast became paperwork this afternoon

Before dawn this morning, four weather offices posted gale watches for the middle of this week, and that was the whole of it. There was not a single coastal flood product active anywhere in the country at 12Z. The water was a forecaster's expectation and nothing more.

At 1:24 this afternoon the Mount Holly office wrote the first of it down. Its own discussion, issued forty minutes later, puts the change in one sentence: "Coastal Flood headlines have been issued. A Coastal Flood Advisory is in effect for tomorrow evening's high tide for coastal counties south of Barnegat Inlet and for Kent County, DE. For those same areas, a Coastal Flood Watch is now in effect for Wednesday and Thursday evening's high tide as Moderate tidal flooding is possible."

The numbers are small, which is the point of them. Tuesday evening, between 4 and 10 p.m. EDT, the advisory expects up to a foot of water above ground level in low-lying places near shorelines and tidal waterways, and up to half a foot on the ocean-facing zones of Cape May, Atlantic and Ocean counties. Wednesday afternoon through late Thursday night, the watch says one to two feet is possible. At that level the product says what happens: widespread roadway flooding in coastal and bayside communities and along inland tidal waterways, many roads impassable, and some damage to vulnerable structures beginning to occur. The advisory also notes that moderate tidal flooding could continue through at least Friday evening's high tide or perhaps longer.

Mount Holly does not think it is finished issuing products. Its third key message reads: "Multiple rounds of potentially significant tidal flooding expected for this week. The first batch of Coastal Flood headlines have been issued with more likely to come."

The coastal flood headlines, NWS Mount Holly NJ

All from the products sent by NWS Mount Holly NJ at 1:24 p.m. EDT on 2026-09-21.

The water offshore, from Nantucket to Hatteras

The marine half of the forecast grew all afternoon. Boston and Norton had watches out at 3:09 a.m. EDT. Wakefield followed at 1:04 p.m., Mount Holly at 1:39, Newport and Morehead City at 1:58, Baltimore and Washington at 2:06, Upton at 2:19. Six offices, twenty six gale watches, all of them for the same three days, and the biggest seas are off North Carolina.

Inside the bays the wind matters more than the waves. The Baltimore and Washington office put a watch on the Chesapeake from Drum Point to Smith Point and on the Tidal Potomac, the Choptank up to Cambridge and the Patuxent. Wakefield put one on the stretch of the Chesapeake that includes the Chesapeake Bay Bridge Tunnel, where gusts to 45 knots and waves of 5 to 8 feet are possible from early Wednesday. Northeast wind blowing up a bay for three days is how you get tidal flooding without a drop of rain falling on the shore.

Gale watches, the worst seas in each office's product

From the gale watches carried on the National Weather Service active alerts feed at 18:19Z on 2026-09-21, twenty six in all across six offices. The same wire run listed 219 small craft advisories nationally.

The office expecting the most water has not written its product yet

The strongest language today came from Wakefield, Virginia, and it is not in a warning. It is in the discussion the office issued at 1:58 p.m. EDT, whose third key message reads: "Widespread moderate to locally major tidal flooding (inundation of 2-3 feet AGL in vulnerable areas) is likely by the Wednesday afternoon/evening high tide due to strong northeast winds. Tidal flooding is expected to continue for several tide cycles (potentially through the end of the work week) given the persistent northeast winds."

That is two to three feet, said as likely, for an area that had no coastal flood product on the wire as of this afternoon's check. Every active coastal flood headline in the country right now came out of one office, Mount Holly. Wakefield's own summary of what changed today lists small craft advisories and gale watches, and a cooler Wednesday as cold air damming sets up. The tidal flooding is in the reasoning, not yet in a product. That is normal, and it is also the most useful thing a reader on the Eastern Shore can know today, because it says what tomorrow's paperwork is likely to look like.

Mount Holly's forecasters add a plainer note for everyone inland: temperatures will likely struggle to get out of the 60s areawide through most of this week.

The rest of the country, briefly

The Storm Prediction Center's day one outlook tops out at Marginal, for isolated damaging wind gusts from parts of the Southeast into the southern and central Appalachians, and an isolated risk of large hail and severe gusts over parts of the Texas South Plains. Five offices had frost advisories out and one had a freeze warning, which is its own kind of news in late September. Three named tropical storms were on the National Hurricane Center's list this afternoon, Fay in the Atlantic and Odalys and Polo in the eastern Pacific, none of them with a watch or warning on United States soil.

And Wednesday is a crowded day. The Beat wrote on Sunday about six Mississippi River gauges in Missouri whose flood warnings begin then, from rain that fell on Iowa last week. A river in the middle of the country and an ocean on the edge of it are both scheduled to arrive at about the same time, for reasons that have nothing to do with each other.

This is a summary of official warnings, not emergency information. For live warnings see weather.gov and your local officials. The offices named here are at https://www.weather.gov/phi/, https://www.weather.gov/akq/, https://www.weather.gov/okx/, https://www.weather.gov/box/, https://www.weather.gov/lwx/ and https://www.weather.gov/mhx/.

The rock's live forecast for the places in this story

• Cape May NJ
• Fenwick Island DE
• Chincoteague VA
• Montauk NY
• Nantucket MA
• Cambridge MD

Key points

• NWS Wakefield issued Coastal Flood Watches at 2:22 p.m. EDT for most of its tidal area. Two to three feet of water above ground level is possible in Hampton Roads, on the Middle Peninsula, along the lower Northern Neck and on the Eastern Shore, from Wednesday afternoon through late Thursday night.
• At 4 p.m. EDT the Baltimore and Washington office put the Maryland Chesapeake Bay, the tidal Potomac, the Choptank up to Cambridge and the Patuxent under a gale watch. The watch now runs from the ocean south of Nantucket to the Alligator River in North Carolina, held by six offices in 26 separate products.
• The low doing all of this still does not exist. Wakefield's 3:05 p.m. EDT discussion credits strong northeast winds and cold air damming, and expects the tidal flooding to last several tide cycles, potentially through the end of the work week.

Wakefield wrote it down at 2:22

This morning the Virginia coast's flooding was a sentence in a forecast discussion. Nothing had been issued. The office said two to three feet of water above ground level was likely by Wednesday's afternoon and evening high tide, and left it at that, because the storm that would do it had not formed.

At 2:22 this afternoon the office signed the products. Six Coastal Flood Watches went out across Virginia, the lower Eastern Shore of Maryland and the top of North Carolina, and the number in them is the same number the forecaster used at dawn: up to two to three feet of inundation above ground level possible in low-lying areas near shorelines and tidal waterways.

The area is wide. Chesapeake, Norfolk, Portsmouth, Suffolk, Virginia Beach and Hampton are in it. So are Newport News, York, James City, Gloucester and Isle of Wight, and so are Accomack and Northampton out on the Eastern Shore, and Inland Worcester County in Maryland. Each of those watches says the same thing about consequences: numerous roads may be closed, low-lying property including homes, businesses and some critical infrastructure may be inundated, and some shoreline erosion may occur.

One watch starts earlier than the rest and runs longest. On the Middle Peninsula and the lower Northern Neck, the counties on the rivers that feed the bay from the west, the watch opens late Tuesday night and does not close until Friday morning.

Sourced from the six NWS Wakefield Coastal Flood Watches listed in the payload, all sent 2:22 p.m. EDT today and read at 8:20 p.m. UTC.

The gale watch went up the bay at four

Earlier today the first coastal flood headlines of the week came out of Mount Holly for southern New Jersey and Delaware, and the marine watches were an ocean story: deep water, offshore, out past the shipping lanes. By this evening the watch had walked inland.

Wakefield's 1:04 p.m. EDT products cover the Chesapeake Bay from Smith Point down to Cape Henry, including the stretch that carries the Chesapeake Bay Bridge-Tunnel, plus the James River up to the Hampton Roads bridge and the Elizabeth River with it. Morehead City took the Albemarle, Croatan and Roanoke Sounds and the Alligator River at 1:58 p.m. EDT. Mount Holly added the Delaware Bay at 1:39 p.m. EDT. Then at 4 p.m. EDT the Baltimore and Washington office put the Maryland half of the bay under a watch too, along with the tidal Potomac as far up as Cobb Island, the Choptank River to Cambridge, and the Patuxent to Broomes Island.

That is a gale watch on rivers, in sounds, and on water that people cross on a bridge to get to work. The wind is the same wind in every one of those products, out of the northeast, for days.

The numbers are worst where the water is deepest and the fetch is longest. They are smallest in the sounds and the bays, and the small ones matter more, because the small ones are where the tide has somewhere to pile up.

Sourced from the 26 active Gale Watches listed in the payload, read at 8:20 p.m. UTC today. Every figure above is the watch level, the possible case, not the advisory conditions the same products expect first. Worth saying plainly: nobody on the East Coast has issued a gale warning. All nine gale warnings active in the country tonight belong to Anchorage and Juneau, in Alaska, for a different weather system entirely.

What the office says is doing it

Wakefield's 3:05 p.m. EDT discussion opens with what changed since the last one, and it is a short list: the flood watches for a large majority of the tidal area, and the gale watches off the North Carolina coast for Wednesday through Friday morning. Two other lines in the same paragraph say the office lowered its Wednesday and Thursday high temperatures further, as cold air damming sets up, and that the Weather Prediction Center introduced a slight risk of excessive rainfall for roughly the western half of the area for Tuesday.

The mechanism, in the office's own third key message, is not the low itself. It is the wind: widespread moderate to locally major tidal flooding, two to three feet above ground level in vulnerable areas, is likely because of strong northeast winds, and the flooding is expected to continue for several tide cycles, potentially through the end of the work week, given the persistent northeast winds.

Canadian high pressure sits to the north. A low is expected to deepen offshore. Between them the air runs one direction for days, and it runs at the coast. The office expects widespread coastal gusts to 25 mph Tuesday, rising to 35 and up to 45 mph along the Atlantic side of the Eastern Shore, naming Ocean City and Chincoteague, Tuesday night into Wednesday, and holds open the possibility of 40 to 45 mph gusts lasting through at least Thursday.

The rest of the week, in that office's area, is cool and wet and unremarkable. Highs in the low to mid 60s inland to the north and west on Wednesday, low to mid 70s toward the southeast. The discussion also notes a secondary surface low may form late Thursday into Friday and pull the main centre a little closer to the coast, which is the part nobody can pin down yet.

This afternoon the same office measured the front it has been writing about all day: readings in the upper 60s at Ocean City and around 90 degrees at the far southern edge of its area, with most places between in the upper 70s to mid 80s. One boundary, twenty-some degrees across it.

Two and a half days from now, the tide will do what the wind tells it. That is the whole forecast, and the useful thing is that it was written down early enough to move a car.

This is a summary of official warnings, not emergency information. For live warnings see weather.gov and your local officials. The National Weather Service pages for these areas are at https://www.weather.gov/akq/, https://www.weather.gov/lwx/, https://www.weather.gov/mhx/, https://www.weather.gov/phi/, https://www.weather.gov/okx/ and https://www.weather.gov/box/.

The rock's live forecast for the places in this story

• Norfolk VA
• Virginia Beach VA
• Chesapeake VA
• Newport News VA
• Chincoteague VA
• Cambridge MD

Key points

• The National Weather Service has several different words for the same salt water, and tonight one stretch of coast is using nearly all of them at once: a coastal flood statement in the Florida Keys for water that is already in the streets, an advisory for tomorrow evening in New Jersey and Delaware, and watches from Cape May, New Jersey to Currituck, North Carolina for Wednesday and Thursday.
• The difference between them is not only how much water. It is how sure the forecaster is. The National Weather Service writes it plainly: a watch is issued "when conditions are favorable for a specific hazardous weather event to occur," and "it does not mean flooding will occur, but it is possible."
• The reason Wednesday is still a watch is that the storm it is written for has not been born. NWS Mount Holly's 7:41 p.m. EDT discussion says the models "fall into two relatively distinct camps" about where the low goes after Friday.

A word for water you are sure about, and a word for water you are not

There is a ladder in every National Weather Service product, and most people only ever meet the top rung of it. Tonight the middle rungs are all visible at once, on one coastline, which does not happen often enough to waste.

Start at the bottom. At 4:28 this afternoon the Key West office put out a coastal flood statement for the Upper, Middle and Lower Keys. Its own words for what is happening are "minor saltwater flooding," and the impacts it lists are the small indignities of a high tide that goes a little too far: some storm drains overflow, some seawalls and docks are overtopped, boaters get less clearance under the fixed bridges. It runs through Tuesday afternoon. That product is not a forecast of trouble. It is a description of water the office already believes is arriving.

Go up one rung. At 1:24 this afternoon, updated at 3:27, NWS Mount Holly issued a coastal flood advisory for tomorrow evening's high tide in Ocean, Atlantic, Cape May and southeastern Burlington counties in New Jersey and for Kent and inland Sussex counties in Delaware, from 4 p.m. to 10 p.m. EDT Tuesday. The number in it is "up to one foot of inundation above ground level expected." Expected. The advisory is the word for a nuisance the office is fairly confident about. The National Weather Service defines the flood version of it as the product issued "when flooding is not expected to be bad enough to issue a warning," though it may cause real inconvenience.

Now the rung that is doing the work tonight. The same Mount Holly product carries a coastal flood watch for Wednesday afternoon through late Thursday night, and the number there is "one to two feet of inundation above ground level possible." Possible, not expected. At six o'clock this evening the Wakefield, Virginia office put watches over most of its tidal area with a larger number still: up to two to three feet possible around Norfolk, Virginia Beach, Chesapeake, Portsmouth and Hampton, and the same figure for the counties on the York River and the Middle Peninsula from late Tuesday night through Friday morning.

Notice what just happened. The watch carries a bigger number than the advisory, and it sits above it in seriousness, but it is the less certain of the two. That is the part of the ladder people trip over. A watch is not a smaller warning. It is a statement about confidence, issued early on purpose, because two to three feet of water in Hampton Roads on Wednesday afternoon is worth knowing about on Monday night even if it does not happen.

The same coast, four rungs, one afternoon and evening

Products read from the National Weather Service active alerts feed at 23:44Z on 2026-09-21: twelve coastal flood watches from two offices, four coastal flood advisories from one, one coastal flood statement, and no coastal flood warnings. The quoted figures are from each product's own WHAT, WHERE and WHEN fields. Definitions quoted from https://www.weather.gov/safety/flood-watch-warning.

The missing rung, and why it is missing

The top of the ladder is the warning, and the National Weather Service's own page is blunt about what it means: a flood warning "is issued when flooding is imminent or occurring." Not likely. Not possible. Happening, or about to.

Tonight there is no coastal flood warning in the country. There were, however, five flash flood warnings, and two of them came from the same Wakefield office that wrote the coastal watches. At 6:47 p.m. EDT it issued one for Bertie County, North Carolina until 9:45, reporting that radar had indicated between one and three inches already fallen and a rate of two inches in thirty minutes. At 7:10 p.m. EDT it issued another for northern Northampton County, North Carolina and for parts of Greensville and Southampton counties and the City of Emporia in Virginia, until 10:15 p.m. EDT. NWS Charleston issued one for five West Virginia counties at 7:38 p.m., NWS Morristown one for part of Washington County, Virginia at 7:37, and NWS Midland one for southwestern Midland County, Texas at 5:53 p.m. CDT.

One office, one evening, both ends of the ladder. Rain that is falling right now gets a warning that expires in three hours. Salt water that may be two feet deep in Norfolk on Wednesday gets a watch that runs for days. The forecaster is not being vague in the second case. The forecaster is being exact about a different thing.

What the forecaster is actually uncertain about

Here is the honest reason Wednesday's water is only "possible," and it is a good one. The low pressure system that would push it ashore does not exist.

Mount Holly's evening discussion, issued at 7:41 p.m. EDT, says confidence "continues to increase" that a mid-level impulse tracking east out of the Midwest and Ohio Valley will produce surface cyclogenesis off the Carolina coast Tuesday into Tuesday night. That is the birth. What the office cannot yet say is where the newborn goes: "Models now fall into two relatively distinct camps, with one camp continuing to take the low northeast and away from the region. The other camp has the low deviating due northward or even northwestward to our region." The office says the difference in outcomes between those two futures is substantial, and it has kept its rain chances at 20 to 40 percent rather than pretending to pick.

The tidal flooding, though, does not depend on winning that argument. It depends on the wind, and the wind is the part both camps agree on. A strong high over Quebec against a low offshore makes a tight pressure gradient, and that gradient means days of northeast wind pushing water up the bays and rivers whether or not the low ever comes close. Wakefield's 3:05 p.m. EDT discussion put it as the reason for the watches in the first place: "Coastal Flood Watches have been issued for a large majority of the tidal area starting Wednesday afternoon/evening high tide," with moderate to locally major tidal flooding likely "due to strong northeast winds," continuing for several tide cycles, potentially through the end of the work week.

So the office is confident about the mechanism and unsure about the storm. A watch is the correct word for exactly that.

What to do with each word

A statement means the water is already doing something small and you should not be surprised by a wet street near the bay. An advisory means an office expects a specific amount of water at a specific tide and has told you which hours. A watch means prepare, and check again, because the number could grow or vanish. A warning means act now.

The practical version for anyone on the Chesapeake or the Jersey Shore this week: Tuesday evening is the advisory, and the number there is a foot. Wednesday afternoon and Thursday are the watch, and the number there is one to three feet depending on where you stand. If those watches become warnings, the water will no longer be a forecast, and the ladder will have gone all the way up.

Mount Holly adds one more plain line for everyone inland, which needs no ladder at all: temperatures will likely struggle to get out of the 60s areawide through most of this week.

This is a summary of official warnings, not emergency information. For live warnings see weather.gov and your local officials. The offices named here are at https://www.weather.gov/phi/, https://www.weather.gov/akq/ and https://www.weather.gov/key/.

The rock's live forecast for the places in this story

• Norfolk VA
• Virginia Beach VA
• Cape May NJ
• Key West FL
• Newport News VA

Key points

• NWS Charleston widened its flood watch at 7:29 p.m. EDT tonight to cover 41 zones, one county in southeast Ohio and most of West Virginia, and extended it through Wednesday morning. NWS Pittsburgh posted a 21 zone watch five minutes later for east central Ohio, southwestern Pennsylvania and the northern West Virginia panhandle.
• Between 7:37 and 9:26 p.m. EDT, four weather offices issued flash flood warnings along the same stalled front: southeastern Washington County in Virginia, five counties of the Kanawha Valley in West Virginia, three counties in the North Carolina coastal plain, and southeastern Pulaski County in Kentucky.
• The Charleston discussion, issued at 7:37 p.m. EDT, ties the rain to the same coastal low the Beat wrote about twice today, and says the flash flooding it is watching for will come at night.

A watch that grew after supper

The forecast office in Charleston, West Virginia spent Monday evening making its flood watch bigger. The version it sent at 7:29 p.m. EDT covers Washington County in southeast Ohio and thirty nine West Virginia counties or county halves, from Wayne and Mingo on the Kentucky border across to Pocahontas and Randolph in the high country, and it runs until 8 a.m. EDT Wednesday. The office explained the change in the first block of its own discussion eight minutes later: "Episodic rounds of showers and thunderstorms attached with heavy rainfall looks to prevail into Wednesday morning, leading to additional potential for flash flooding. With that in mind, opted to extend the Flood Watch in time and also revamp the coverage of the Watch to include more of our West Virginia counties. Rain chances stretch through the overnight hours, amplifying concerns of nighttime flash flooding."

Five minutes after Charleston sent its watch, the Pittsburgh office sent one of its own, through Wednesday morning, for Belmont, Monroe and Noble counties in Ohio, Allegheny and five other counties in Pennsylvania, and eleven areas of northern West Virginia including Monongalia, Preston and the Tucker county highlands.

Two things are worth saying plainly about a watch. It is not a warning, and the ground it covers is not the ground that will flood. Charleston's second key message tonight is about Thursday and the weekend turning cooler and drier. What the office is asking for in the meantime is in its first: "Nighttime flash flooding will be possible tonight and Tuesday night across the area, so ensure you have multiple ways of receiving warnings that may be issued over the next few days."

The two flood watches

Both products carried on the National Weather Service active alerts feed, read at 01:30Z on 2026-09-22. Zone counts are the products' own affected zone lists.

Four warnings between supper and half past nine

The warnings came one office at a time as the front sat where it was. Morristown went first, at 7:37 p.m. EDT, for the corner of Washington County, Virginia that holds Damascus. Charleston followed a minute later with five counties of the Kanawha Valley, a list of twenty towns, and the stretch of the West Virginia Turnpike between mile markers 73 and 90. Raleigh came at 8:20 p.m. for the coastal plain around Tillery, where its radar had already measured two to four inches. Jackson, Kentucky came last, at 9:26 p.m., for the country around Burnside above Lake Cumberland.

One detail from the Charleston list is a coincidence and nothing more, but it is a real one. Among the towns that office named is Chesapeake, West Virginia, on the Kanawha River, about four hundred miles inland from the Chesapeake Bay this site wrote about earlier today.

The flash flood warnings, sent Monday evening

All four give their source as radar indicated, and all four give the same impact sentence: flash flooding of small creeks and streams, urban areas, highways, streets and underpasses as well as other poor drainage and low lying areas. Three more flood advisories, a step below a warning, were out at the same hour for Pike County in Kentucky, for Clinton, Cumberland and Russell counties in Kentucky, and for Durham, Orange, Granville and Person counties in North Carolina, where the Raleigh office measured one to three inches over Durham and Chapel Hill and reported the rain easing at 8:53 p.m. EDT.

Why the same hills, two nights running

The Jackson, Kentucky discussion at 6 p.m. EDT put the setup in one line: a weak cold front has been sinking south all day and has stalled across the southeastern terrain, where it is expected to stay for about a day. Fronts that stop moving are how a summer pattern gets expensive in September.

The Raleigh office wrote down the part that makes the rain totals large. Its Monday afternoon discussion notes precipitable water values of 1.6 to 2 inches, well above normal, with mean winds through the lowest six kilometres of the atmosphere of only about five knots, which it says results in "very slow-moving storms and possible merging and training of cells." A storm that does not move rains on one place for an hour instead of on six places for ten minutes each. Raleigh also expected the flooding from it to stay isolated and mostly urban, because the ground there went into the day dry.

West Virginia is the opposite case, and Charleston said so: the rain has been landing on the same hills for days. Its discussion tonight says the forecast "shifts the attention off of an already battered southeast Ohio east of the river to mainly West Virginia," with another one to two inches possible, and puts the highest flash flood concern across northeastern West Virginia and down the spine of the Appalachians.

The last sentence of that paragraph is the one that connects this story to the other two the Beat filed today: "An inverted trough feature setting up over this region, in tandem with a coastal low riding up along the eastern seaboard, will promote episodic rounds of showers and storms through midweek." The same developing low that has six offices holding gale watches from Nantucket to Cape Hatteras, and two offices holding coastal flood watches from New Jersey to Hampton Roads, is also the reason the water keeps coming down over the coalfields. It is one map.

The rest of the country, briefly

Four severe thunderstorm warnings were on the wire at 9:30 p.m. EDT, all of them for wind and small hail: two from Mobile, Alabama for slow moving storms near Citronelle and Stockton, one from Greenville and Spartanburg for Cleveland County, North Carolina and Cherokee County, South Carolina, and one from Jackson, Kentucky for a storm near Somerset, all at 60 mph gusts with penny or quarter size hail. The Storm Prediction Center's day one outlook tops out at Marginal, the lowest of its five categories, for "isolated severe wind gusts ... from parts of the Southeast into the southern Appalachians and southern Mid-Atlantic."

Elsewhere on the alert list at that hour: 191 small craft advisories, five frost advisories and one freeze warning, a flood watch running from Tuesday afternoon through Wednesday evening across south central and southwestern New Mexico and El Paso County, Texas, and the Mississippi River flood warnings in Missouri this site wrote about on Sunday, whose rises begin Wednesday. The National Hurricane Center listed three storms at its 8 p.m. EDT advisory: Tropical Storm Fay in the open Atlantic near 33.1 north, 32.2 west; Tropical Storm Odalys in the eastern Pacific; and Hurricane Polo, 80 knots and 971 millibars, near 15.2 north, 102.4 west, moving east at 6 knots off southwestern Mexico. No tropical storm or hurricane product appeared anywhere on the National Weather Service active alert list tonight.

Two sources were unreadable from here again. The Storm Prediction Center's preliminary storm reports for Sunday and the Weather Prediction Center's day one excessive rainfall outlook both answered our wire with HTTP 403 for the sixth consecutive day, so yesterday's report counts and the national rain risk map are absent from this brief rather than summarized secondhand.

This is a summary of official warnings, not emergency information. For live warnings see weather.gov and your local officials. The offices named here are at https://www.weather.gov/rlx/, https://www.weather.gov/pbz/, https://www.weather.gov/jkl/, https://www.weather.gov/rah/ and https://www.weather.gov/mrx/.

The rock's live forecast for the places in this story

• Montgomery WV
• Gauley Bridge WV
• Marmet WV
• Damascus VA
• Burnside KY
• Scotland Neck NC
• Durham NC

Key points

• The heavy rain that fell on eastern Iowa from Thursday into Saturday night is finished, and the National Weather Service office at the Quad Cities said so in its 1:22 p.m. CDT discussion today: "The widespread heavy rains are over."
• The water is not finished. Six Mississippi River gauges from Canton, Missouri down to Winfield, Missouri were put under flood warnings at 11:48 a.m. CDT today for flooding that does not begin until Wednesday.
• Two Iowa rivers were upgraded today from moderate to major flooding: the English River at Kalona and the Wapsipinicon near De Witt.

What happened, and where the water went

The rain stopped. That is the honest headline in eastern Iowa this afternoon, and the forecasters there wrote it plainly. The Quad Cities office, in the discussion it issued at 1:22 p.m. CDT, led with the line that the widespread heavy rains are over, that a small upper low will keep spinning nearby with showers and cool cloudy conditions through Tuesday morning, and that additional rain over the next 24 hours will be very light. It also reported that on the creeks under areal flood warnings this morning, including Indian Creek in Linn County, "the water was reported to have stopped rising early this morning."

So the sky is done with it. The ground is not, and neither is the river system, because a river is a delivery schedule. What fell on Iowa Thursday through Saturday has to get to the Gulf, and the gauges along the way tell you when it will pass each town.

Close to the rain, the crest is already here or nearly here. The English River at Kalona stood at 17.6 feet at 9 a.m. CDT and was still slowly rising toward a crest of 18.1 feet this evening, against a flood stage of 14 feet. That gauge got the day's most serious wording: the Quad Cities office changed its forecast for Kalona from moderate to major severity, and the product says at 18 feet water has overtopped 130th Street, Kiwi Avenue, Orange Avenue and Poplar Avenue, and begins backing into town on the north side of the river. The Wapsipinicon near De Witt got the same upgrade with a slower clock, moderate flooding happening now and major flooding forecast at a crest of 13 feet Wednesday afternoon into Thursday, where water affects many residences along the river.

Then the handoff. The Rock River at Moline, Illinois was 9.5 feet and rising this morning and is not expected to reach its 12 foot flood stage until Monday evening, cresting at 13.6 feet Tuesday evening. Farther down, the Iowa River at Marengo goes over this evening. Each of those is water that fell days ago, moving.

The last stop in today's paperwork is the main stem. At 11:48 a.m. CDT the St Louis office issued flood warnings for six Mississippi River gauges at once: Canton, LaGrange, Saverton, Hannibal, Clarksville and Winfield, all in Missouri, with the Illinois bank counties named alongside. Not one of them is above flood stage today. Canton was at 7 feet this morning against a 15 foot flood stage. Saverton was at 7.7 feet against 16. The warnings begin Wednesday and run into next weekend, and every crest in the set lands Thursday or Friday.

What makes those products worth reading is that the Weather Service says exactly what goes under at each number, and the numbers are small and specific. At Canton, 16.6 feet puts water on Front Street leading to the campground. At LaGrange, 18 feet floods the entrance to the lower parking lot at the Mark Twain Casino and sends cars around to another entrance. At Hannibal, 18 feet floods the north end of Southside Recreation Park Number 2 along Bear Creek, the gate wells are shut down to keep the sewers from backing up, and the pumps go to standby. At Saverton, 15.5 feet floods the access road to the raised riverside homes on the river side of the Sny levee. At Clarksville, 29 feet puts water into the parking lot entrance at the Riverfront Park. At Winfield, 27.5 feet is the stage at which Lock and Dam 25 stockpiles 200 tons of sand, 12,000 sandbags and 10,000 square feet of polyethylene plastic as a precaution.

That last one is the whole story in one sentence. Somebody in Winfield now has four days to move sand, because a river in Iowa stopped rising this morning.

Mississippi River, the six gauges under warning

All six are forecast for minor flooding. From the flood warnings issued by NWS St Louis at 11:48 a.m. CDT on 2026-09-20, which state that river forecasts are based on observed precipitation plus forecast precipitation for the next 24 hours.

Upstream, where the water is now

From flood warnings issued by NWS Quad Cities IA IL between 9:23 a.m. and 10:10 a.m. CDT on 2026-09-20. Each of those products carries the same confidence note: rainfall from today through Monday night is expected to be considerably lighter than what fell Thursday through Saturday night, which is why the forecasters trust these river numbers.

Today, officially

As of the wire at 6:46 p.m. UTC there were 371 active National Weather Service alerts nationally, of which 43 were flood warnings across 10 offices and 20 were flood watches across 9. The Storm Prediction Center's day one outlook carried a highest risk category of slight, for thunderstorms with severe wind gusts and large hail across parts of Oklahoma and from eastern Colorado into far western Kansas, with isolated severe gusts and hail also possible from the southern Plains through the Ozarks and into the Ohio Valley. The National Hurricane Center's 15:00 UTC advisories carried Tropical Storm Fay in the Atlantic at 50 knots and Tropical Storm Odalys in the eastern Pacific at 40 knots, neither with a United States watch or warning.

Two of the wire's usual sources refused us today. The Storm Prediction Center's preliminary storm reports for yesterday and the Weather Prediction Center's day one excessive rainfall outlook both returned HTTP 403 to our fetcher, so this brief carries no yesterday report counts and no rainfall risk categories. That is our tool being turned away, not a quiet country, and it is said here rather than left as a silence.

One more note for anyone in the St Louis forecast area reading this: that office's own 12:35 p.m. CDT discussion says a cold front is moving through today with thunderstorms along it tonight, the best chance of rain all week, and that the severe potential is not being messaged for the event because the threat is limited. Any rain that falls tonight on the Missouri and Illinois side gets added to the numbers in the table above when the next river forecast runs.

This is a summary of official warnings, not emergency information. For live warnings see weather.gov and your local officials.

The rock's live forecast for the places in this story

• Kalona IA
• De Witt IA
• Marengo IA
• Moline IL
• Canton MO
• LaGrange MO
• Saverton MO
• Hannibal MO
• Clarksville MO
• Winfield MO

Key points

• Emergency management in Denison, Texas reported multiple impassable roads and potential water rescues at 6:27 p.m. CDT Sunday, and the National Weather Service office at Fort Worth put the words "Life threatening flash flooding" in the warning it issued for east central Grayson County.
• Across the Red River in Bryan County, Oklahoma, between 2 and 3.5 inches of rain had fallen by 7:18 p.m. CDT, with Durant, Calera, Colbert, Achille and Mead named in the warning.
• Seventeen minutes before its first Denison warning, the same Fort Worth office called the day's rain beneficial. Both lines were written by the same forecasters on the same evening, and both were about the same storms.

Sunday evening on the Red River

The thing that makes a flash flood warning worth reading is the line that says where the information came from. Most of them say "Radar indicated." Two of tonight's said something else.

At 6:18 p.m. CDT the Fort Worth office issued a flash flood warning for central Grayson County, Texas, and under SOURCE it wrote "Emergency management reported." The product said that as of 6:18 p.m. CDT, emergency management had reported multiple flooded roads and vehicles stuck in flood water in and around the Denison area, that flash flooding was already occurring there, and that more was imminent or occurring from Sherman to Southmayd. It named Pottsboro, Knollwood, Randell Lake, Eisenhower State Park, Boddie and Carpenters Bluff alongside them.

Nine minutes later the office issued a second warning, this one for east central Grayson County, running until 8 p.m. CDT. Its report was from 6:27 p.m. CDT and it was worse: multiple un-passable roads and potential water rescues ongoing in Denison. That product carried the hazard line the Weather Service reserves for the serious ones, "Life threatening flash flooding," and one instruction, which was to stay off the roads unless absolutely necessary.

Neither warning gave a rainfall total, because nobody had measured one yet. The office across the river did. At 7:18 p.m. CDT the Norman office warned Bryan County, Oklahoma, the county that holds Durant and the eastern end of Lake Texoma, and put a number on it: between 2 and 3.5 inches had already fallen, no more was expected, and the flooding would continue anyway. That is the ordinary arithmetic of a flash flood. The sky can finish and the water can keep going for hours.

By 7:11 p.m. CDT the picture had widened rather than worsened. Fort Worth dropped the area down a tier to a flood advisory covering Fannin County and southern Grayson County until 9:30 p.m. CDT, a product about ponding, low water crossings and minor flooding, naming Bonham, Van Alstyne, Howe, Whitewright and Bonham State Park. Three different products for three different severities inside two counties in one hour is not a mess. It is the system working at the resolution it was built for.

What was issued, Sunday evening

Warning times are the times the products were sent. All four expired Sunday night. Locations listed in the warnings include Sherman, Denison, Pottsboro, Southmayd and Carpenters Bluff in Texas, and Durant, Colbert, Achille, Calera, Silo, Hendrix, Cartwright, Mead and eastern Lake Texoma in Oklahoma.

What the forecasters had said

At 6:01 p.m. CDT, in the update that went into its 6:13 p.m. area forecast discussion, the Fort Worth office wrote that isolated to scattered thunderstorms might persist a few more hours on outflow mergers, that areas from Arlington southwest to Hamilton "have received beneficial rainfall today, along with the Sherman/Denison area," and that a few storms had become severe with damaging wind gusts. It added that frequent lightning and heavy rain had come with several of them.

That was seventeen minutes before the first Denison warning. Both statements are accurate, and the gap between them is the whole difference between a rain gauge and a street. North Texas has been dry and the rain was wanted. In one corner of one county it arrived faster than the drains could take it, and the people who found that out first were driving.

The afternoon discussion, issued at 2:24 p.m. CDT, had set it up honestly enough. A cold front was still well removed from the area, a shortwave was approaching from the west, and a sharp moisture gradient had set up just west of the I-35 corridor with dew points falling off quickly to the west of it. Deep layer shear was modest, so the forecasters expected multi-cell to loosely organized clusters rather than anything rotating, with strong to damaging winds the main risk and hail up to about an inch. Slow, clustered, wet storms on a moisture boundary are exactly the kind that put 3 inches on one county and none on the next.

On the Oklahoma side, the Norman office's 1:25 p.m. CDT discussion had the same front moving south through the state, 1500 to 2500 joules per kilogram of instability, damaging winds and hail as the concerns, and one more hot day ahead of the front across southern Oklahoma and western north Texas, with heat index values near 105. The front brought the relief and the storms in the same package, which is usual.

Today, officially

As of the wire at 00:35 UTC on 2026-09-21 there were 465 active National Weather Service alerts nationally. Most of them were marine: 296 small craft advisories across 23 offices and 52 gale warnings across 2. On land the count was led by 38 flood warnings across 9 offices and 18 flood watches across 7, which is the upper Midwest river flooding this desk wrote about Sunday afternoon and which has not changed. There were 11 flood advisories across 6 offices, including two in Kerr County, Texas and two in the Dayton area of southwestern Ohio.

The Storm Prediction Center's day one outlook carried a highest risk category of slight, for severe wind gusts and large hail across parts of Oklahoma and from eastern Colorado into far western Kansas, with isolated severe gusts and hail also possible from the southern Plains eastward through the Ozarks into the Ohio Valley. Severe thunderstorm watch 673 covered nine counties in southeast and east central Colorado and west central Kansas, including Lamar, Eads, Burlington, Cheyenne Wells, Leoti, Oakley, Sharon Springs, Tribune and Syracuse, until 9 p.m. MDT.

The National Hurricane Center's 21:00 UTC advisories had Tropical Storm Fay in the Atlantic at 55 knots, Tropical Storm Odalys in the eastern Pacific at 45 knots, and a new Tropical Depression Seventeen-E in the eastern Pacific at 30 knots. None of the three carried a United States watch or warning.

For the fourth day running, two of the wire's five sources refused our fetcher. The Storm Prediction Center's preliminary storm reports for yesterday and the Weather Prediction Center's day one excessive rainfall outlook both returned HTTP 403, so this brief carries no yesterday report counts and no rainfall risk categories. That is our tool being turned away and not a quiet country, and it is said here rather than left as a silence.

This is a summary of official warnings, not emergency information. For live warnings see weather.gov and your local officials.

The rock's live forecast for the places in this story

• Denison TX
• Sherman TX
• Pottsboro TX
• Southmayd TX
• Bonham TX
• Van Alstyne TX
• Durant OK
• Colbert OK
• Calera OK
• Achille OK
• Mead OK

Key points

• Port Isabel, Texas measured 12.0 inches of rain on September 19, 1984, its wettest day on record in a span running from 1896 to 2026.
• The same gauge is the nearest station of record for three neighboring towns at the southern tip of Texas: Laguna Vista, Laguna Heights and Del Mar Heights.
• The house archive holds the total itself, not a cause; no storm or system is named in the record, and none is claimed here.

A gauge at the foot of the Laguna Madre

Our house archive keeps a running tally of the hottest, coldest, wettest and snowiest day each station has ever measured. On the calendar date of September 19, the record for Port Isabel, Texas reads 12.0 inches of rain in a single day, on September 19, 1984, the most that gauge has recorded since its data begin in 1896, a span of 130 years running through 2026.

Port Isabel sits on the Laguna Madre, the shallow bay behind South Padre Island, at the far southern end of the Texas Gulf coast. The same gauge is the nearest station of record for three other towns nearby: Laguna Vista, about a mile off; Laguna Heights, roughly three miles off; and Del Mar Heights, about eight miles off. All four share this one day as their wettest on record.

The house archive records what the gauge measured and the date it happened. It does not name a storm, a front, or a cause, and none is offered here. Readers who want the meteorological story behind a specific date are better served by the National Weather Service's own post-event write-ups, where they exist; this desk did not find one in hand tonight that it could quote by name for this date and station, so the total stands on its own.

The record, for the nerds

Sources: the house NOAA station archive, read by beat-history.py on 2026-09-19. Every figure above is a line the archive tool printed.

This is a historical summary, not emergency information. For live warnings see weather.gov and your local officials.

The rock's live forecast for the places in this story: Port Isabel TX | Laguna Vista TX | Laguna Heights TX | Del Mar Heights TX

The rock's live forecast for the places in this story

• Port Isabel TX
• Laguna Vista TX
• Laguna Heights TX
• Del Mar Heights TX

Key points

• The National Weather Service issued three Flash Flood Warnings Friday morning for thunderstorms over three separate 2026 wildfire burn scars in Idaho, warning of debris flows of rock, mud and vegetation.
• A Flash Flood Watch covers six areas of south central and southwest Idaho through Friday evening for the Wapiti, Crooked and Buckhorn burn scars, naming more than a dozen communities that could see flash flooding.
• Two more Flash Flood Watches cover parts of southwest and central Montana into Saturday, for the Sand Creek, Bobcat Lakes and Horse Gulch burn scars and other ground burned this summer.

Burn scars, not open ground

Friday's flash flood threat in Idaho and Montana is not ordinary heavy rain on ordinary ground. Every warning and watch the National Weather Service issued Friday morning names a specific wildfire burn scar, land stripped of the vegetation that would normally slow runoff, where the same rain that would soak into a hillside elsewhere instead sheets off fast enough to carry rock, mud and vegetation downslope.

The National Weather Service's Pocatello office issued two of the warnings. One, issued at 10:44 a.m. MDT and running until 1:45 p.m., covered the Big Rock Burn Scar in southeastern Jefferson and south central Madison Counties, naming Heise as a location that would experience flash flooding. Radar indicated thunderstorms producing heavy rain with an expected rate of 0.5 to 1 inch per hour, and the warning called the hazard "life threatening flash flooding." A second Pocatello warning, extended at 11:50 a.m. MDT to run until 2:15 p.m., covered the Ohio Burn Scar in northwestern Blaine County, where radar had already measured between 0.5 and 1 inch of rain with another 0.5 to 1 inch per hour expected.

The National Weather Service's Boise office issued the third warning at 11:49 a.m. MDT, running until 2:00 p.m., for the MM115 Highway 20 Burn Scar in central Elmore County, with an expected rainfall rate of 0.25 to 0.75 inches per hour. Boise also issued a Flash Flood Watch at 10:50 a.m. MDT, running through Friday evening, covering the Wapiti, Crooked and Buckhorn burn scars across the West Central Mountains, Boise Mountains, Camas Prairie, Lower and Upper Treasure Valley and Western Magic Valley. That watch named Idaho City, Fairfield, Lowman, Horseshoe Bend, Pine, Prairie, Atlanta, Anderson Dam, Corral, Centerville, Pioneerville, Garden Valley, Banks and Gardena as places that could see flash flooding.

In Montana, the National Weather Service's Great Falls office issued two Flash Flood Watches at 10:39 a.m. MDT. One runs from 3 p.m. Friday through Saturday afternoon for the Sand Creek and Bobcat Lakes burn scars in northwest Beaverhead County. The other runs from 6 p.m. Friday through Saturday evening for the Horse Gulch area and burn scars from the summer of 2026, across the Little Belt and Highwood Mountains, the Big Belt, Bridger and Castle Mountains, and the Elkhorn and Boulder Mountains. Both watches warn that heavy rainfall over the burn scars could trigger flash flooding of low-lying areas, street flooding, and debris flows.

The warnings and watches, for the nerds

Source: National Weather Service active alerts API, fetched 2026-09-18 18:04Z. Every location, time and rainfall rate above is quoted from the alert text itself.

This is a summary of official warnings, not emergency information. For live warnings see weather.gov and your local officials.

The rock's live forecast for the places in this story: Idaho City ID | Fairfield ID | Lowman ID | Horseshoe Bend ID | Pine ID | Prairie ID | Atlanta ID | Corral ID | Centerville ID | Pioneerville ID | Garden Valley ID | Banks ID | Heise ID

The rock's live forecast for the places in this story

• Idaho City ID
• Fairfield ID
• Lowman ID
• Horseshoe Bend ID
• Pine ID
• Prairie ID
• Atlanta ID
• Corral ID
• Centerville ID
• Pioneerville ID
• Garden Valley ID
• Banks ID
• Heise ID

Key points

• As of Thursday morning, the National Weather Service had Flood Warnings covering at least 16 counties across seven states, from Iowa to Florida, meeting the day's threshold for river flooding on the wire.
• The Wabash River near Linn Grove, Indiana, was forecast to crest at a level the warning itself called approaching the flood of record, with some evacuations possible.
• Only one of the eight warnings names rain as a stranger cause: the Withlacoochee River in Florida has been rising since July because aquatic weed growth is damming the channel, not because of a storm.

A river rise with no single storm behind it

None of Thursday's flood warnings share a weather system. They share a threshold: enough counties, in enough states, to be the day's flood story on the wire, and each one is worth its own line.

The sharpest number sits on the Wabash River in northeast Indiana. The National Weather Service's Northern Indiana office, in warnings issued at 6:25 a.m. EDT Thursday, said the river near Linn Grove was forecast to rise to 14.3 feet against a flood stage of 11.0 feet, and wrote plainly that this approaches the flood of record. At that level, the warning said, secondary roads are blocked, roads near the east side of Geneva begin to flood, and some evacuations may be required. A separate segment of the same river near Bluffton, in Wells County, was reported minor: a crest of 12.6 feet against a flood stage of 10.0 feet, enough to flood the access road to the Bluffton wastewater treatment plant.

In southwest Iowa, NWS Omaha/Valley said small stream flooding on the East Nishnabotna River near Riverton, in Fremont and Page Counties, followed excessive rainfall and was expected to end by 9:45 a.m. CDT Thursday.

Missouri and Kansas carried three more river warnings from NWS Kansas City/Pleasant Hill, all issued Wednesday night: the Grand River near Sumner, forecast to reach moderate flooding across Chariton, Carroll, Livingston and Linn Counties; the Platte River near Agency in Buchanan County, forecast to minor flood stage; and Stranger Creek at Easton, on the Atchison-Leavenworth county line, also forecast to minor flood stage.

In central Arizona, NWS Phoenix warned Maricopa and Pinal Counties overnight for flooding from excessive rainfall, with a county flood-control gauge already reading flood stage on the East Maricopa Floodway and low-water crossings at risk in rural parts of both counties into Thursday morning.

The odd one out is in Florida. The Withlacoochee River at Dunnellon, spanning Marion, Citrus and Levy Counties, has been rising since July and reached flood stage on September 15, but NWS Tampa Bay Ruskin's warning gives a cause with no rain in it: excessive hydrilla growth, from the river bottom to the surface, along a 4.5 mile stretch between US 41 and Lake Rousseau, acting like a dam and holding water back. The warning carries no rain in the forecast and no end date, only "until further notice," with the river's 28.2 foot stage compared in the product itself to a previous crest of 28.4 feet on August 25, 2008.

The warnings, for the nerds

Source: NWS active alerts API, fetched 2026-09-17 11:55Z. Stage, flood-stage and crest figures are quoted from each warning's own WHAT/WHERE/ADDITIONAL DETAILS text; "per product" marks the river's own forecast-crest date, which can differ from the alert's technical expiration field.

This is a summary of official warnings, not emergency information. For live warnings see weather.gov and your local officials.

The rock's live forecast for the places in this story

• Bluffton IN
• Geneva IN
• Riverton IA
• Sumner MO
• Agency MO
• Easton KS
• Dunnellon FL

Key points

• The hottest day in Santa Barbara's record book is September 17, 1913, when the town gauge read 108.0 degrees.
• The archive behind our town pages runs that station from 1893 to 2026, and nothing in those years has topped it.
• Our archive holds 215 record days for this four day stretch of the calendar, 64 of them on September 17 alone.

The day the coast read 108

The hottest day Santa Barbara has on file is not in July. It is not in August. It is the middle of September.

On September 17, 1913, the Santa Barbara gauge, station USC00047902, read 108.0 degrees. The record behind our town pages runs that station from 1893 to 2026. In all of those years, through every summer anyone alive has sat through, no day has come in higher. The number has stood for 113 Septembers.

That is a strange reading for the place. Santa Barbara is a coastal town, and coastal towns are supposed to be the ones that stay cool while the valleys cook. Something turned that arrangement around for a day.

Here is where the rock stops. Our archive records what the thermometer did. It does not record why. There is no NOAA or Weather Service page this desk could pull tonight that explains the 1913 reading, so no explanation appears here. The number is verified. The cause is not ours to offer.

One gauge does a lot of work on that stretch of coast. The same station is the nearest record for six of our towns, from Santa Barbara itself out to Carpinteria about eleven miles down the shore, which means 108.0 is the standing figure on all six town pages rather than six separate measurements. It is one day, told six times.

It is worth knowing that mid September is busier in the record book than most people would guess. Counting today and the three days after it, our archive turns up 215 record days somewhere in the country. September 17 carries 64 of them by itself, from a 105.1 degree afternoon in Granite Falls, Minnesota in 1895 to a run of Puerto Rico rainfall records in 1975. Late summer does not end politely.

The record, for the nerds

Source: the house NOAA station archive, read by beat-history.py on 2026-09-15. Every figure above is a line that tool printed. No figure here comes from anywhere else.

This is a historical summary, not emergency information. For live warnings see weather.gov and your local officials.

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The rock's live forecast for the places in this story

• Santa Barbara CA
• Montecito CA
• Mission Canyon CA
• Summerland CA
• Toro Canyon CA
• Carpinteria CA

Key points

• Three gauges across the southwest corner of Puerto Rico, at La Parguera, Lajas and Guánica, each show their wettest day on record falling on the same date: September 17, 1975.
• The wettest of the three, at La Parguera's Magueyes Island station, measured 13.902 inches in that single day, in a record that runs from 1959 to 2026.
• Our archive holds 64 record days on the calendar for September 17 alone; this is the biggest single-day rainfall total among them.

The day three Puerto Rico gauges maxed out together

Our house archive keeps a running tally of the hottest, coldest, wettest and snowiest day each station has ever measured. On the calendar date of September 17, three of those stations, all sitting within a few miles of each other on the southwest coast of Puerto Rico, point to the exact same day: September 17, 1975.

The biggest number belongs to Magueyes Island, the station behind our La Parguera town page. It measured 13.902 inches of rain that day, the most rain that gauge has recorded in a single day across a record that runs from 1959 to 2026. Four miles up the coast, the Lajas substation measured 12.26 inches, its own wettest day in a record stretching back to 1900. And at Ensenada, a mile inland from Guánica, the gauge read 10.299 inches, also its wettest day on file, in a record running from 1959 to 2026.

Here is where the archive stops. It records what each gauge measured and the date it happened; it does not record a cause. This desk has no NOAA or National Weather Service page in hand tonight that names what produced the rain over southwest Puerto Rico on September 17, 1975, so none is offered here. The three numbers are verified. Any explanation of the weather system behind them is not.

The Lajas gauge speaks for the most ground: it is the nearest station of record for twelve of our town pages, from Lajas itself out through San Germán, Cabo Rojo and Boquerón to El Combate at the island's southwest tip. The Guánica gauge covers five town pages nearby, including El Tumbao and Indios. La Parguera's own gauge sits close enough to town, two tenths of a mile, that it speaks only for itself.

The three gauges, for the nerds

Towns the Lajas gauge speaks for: Lajas, Maguayo, Sabana Eneas, San Germán, Betances, Monte Grande, Cabo Rojo, Boquerón, Puerto Real, Hormigueros, Pole Ojea, El Combate.

Towns the Guánica gauge speaks for: Guánica, Fuig, El Tumbao, María Antonia, Indios.

Source: the house NOAA station archive, read by beat-history.py on 2026-09-17. Every figure above is a line that tool printed. No figure here comes from anywhere else.

This is a historical summary, not emergency information. For live warnings see weather.gov and your local officials.

The rock's live forecast for the places in this story

• La Parguera PR
• Lajas PR
• Maguayo PR
• Sabana Eneas PR
• San Germán PR
• Betances PR
• Monte Grande PR
• Cabo Rojo PR
• Boquerón PR
• Puerto Real PR
• Hormigueros PR
• Pole Ojea PR
• El Combate PR
• Guánica PR
• Fuig PR
• El Tumbao PR
• María Antonia PR
• Indios PR

Key points

• Emergency management in Adair County, Iowa reported numerous closed roads on Tuesday evening after 2 to 4 inches of rain, with a flood warning running to Wednesday afternoon and Interstate 80 named in the product.
• As of the 8:12 p.m. CDT Tuesday flood watch, heavy rain was expected to expand across southern into central Iowa overnight into Wednesday morning, onto soils the Des Moines office measured at 50 to 90 percent of saturation in its southernmost counties.
• Fourteen flash flood warnings were in force across six Weather Service offices on Tuesday evening, from slot canyons in Utah's San Rafael Swell to the Frijoles burn scar in New Mexico and the Texas South Plains.

Yesterday: the water got ahead of Iowa

Iowa has had this rain before. That is the part that matters.

Tuesday afternoon and evening, September 15, the Weather Service office in Des Moines was not writing about a storm so much as about ground that had run out of room. By 8:07 p.m. CDT, Adair County emergency management had told the office that numerous roads in the county were closed and that water was coming up on Highway 25 south of Greenfield. Between 2 and 4 inches of rain had fallen. The warning the office put out three minutes later named the Middle River, listed Greenfield, Stuart, Adair, Fontanelle, Orient and Bridgewater, and included Interstate 80 between mile markers 73 and 96. Not a radar estimate. People on the ground, reporting closed roads.

Twenty five miles of interstate is a plain way to say how wide a small stream flood can reach in farm country, where the road and the creek have to share the same low spot.

The rivers were doing the slower version of the same thing. At 1:32 p.m. CDT the Raccoon River at the Fleur Drive gauge in Des Moines stood at 12.0 feet and rising, with minor flooding forecast and 13.5 feet the level at which water starts into the low parts of Water Works Park. West of there, the East Nishnabotna at Red Oak read 17.6 feet at 4 p.m. CDT against a bankfull stage of 18.0, and the Omaha office had it cresting at 19.7 feet just after midnight.

In its 6:39 p.m. CDT discussion the Des Moines office described a state cut in three: dry with some sun in the north, warm and humid with some sun in the far southeast, and "off and on showers" in between. The office wrote that many rivers and streams south of Highway 30 had risen, mostly within their banks, "but a few locations have reached or exceeded minor flood stage." It had already trimmed the flood watch off its northern counties twice in one day, once in the morning and again that afternoon, because the problem was moving south.

Iowa, for the nerds

Source: NWS active alerts and the KDMX Area Forecast Discussion issued 6:39 p.m. CDT September 15, 2026, read at 1:31 a.m. UTC September 16. Gauge stages are the values the products state.

Yesterday: canyon country had its own kind of day

The other half of the country's water was in places that hold none of it.

Tuesday evening in the interior West, eleven flash flood warnings were out at once across Utah, Arizona, Colorado and New Mexico, and the wording in them was the wording offices reserve for terrain that turns rain into a moving wall. At 7:09 p.m. MDT the Salt Lake City office extended a warning for south central Emery County, Utah for another half inch to inch of rain over the San Rafael Swell, and it listed the drainages by name: Muddy Creek, Ramp, Cistern, Ding, Dang, Bell, Little Wildhorse, Crack and Chute Canyons. The office called it "another flood wave moving through these drainages." An earlier warning that evening covered Iron Wash, Ernie Canyon and Eardley Canyon on half an inch of rain, which tells you most of what you need to know about how slot canyons work.

In Arizona, the report came from a person rather than a radar beam. At 5:48 p.m. MST the Flagstaff office wrote that the public had reported flash flooding across Gila and Navajo counties, including on Fort Apache Road, with up to 3 inches of rain fallen. The towns listed were Fort Apache, Whiteriver, Canyon Day, Turkey Creek, Seven Mile and East Fork. Twenty one minutes later the same office had a separate warning for Apache County with 1.5 to 3 inches already down.

New Mexico had the case that needs no rain at all to be a problem. At 6:43 p.m. MDT the Albuquerque office extended a warning for the Frijoles burn scar in southeastern Rio Arriba and northeastern Santa Fe counties on 1 to 1.75 inches of rain, naming Chimayo and Cundiyo. Burned ground sheds water like pavement. An inch there is not an inch somewhere else.

And on the Texas South Plains, three counties were under flash flood warnings on real measurements rather than estimates. The Lubbock office had radar and automated rain gauges putting 2 to 4 inches over Hale and Lubbock counties by 7:48 p.m. CDT, with the 7:48 product stating flatly that "flash flooding is already occurring." A fourth warning followed for Lamb County at 8:01 p.m. CDT on up to 3 inches.

The flash flood warnings, for the nerds

Source: NWS active alerts read at 1:31 a.m. UTC September 16, 2026. Rainfall figures are the amounts each product states, from radar, automated gauges or public report as each product says. Times are local to each warning.

Today, officially

The expectation, as of the products on the wire at 1:31 a.m. UTC Wednesday:

The Des Moines flood watch, issued 8:12 p.m. CDT Tuesday and running through Wednesday afternoon, covers 19 counties in central and southern Iowa and says heavy rainfall "expands across southern into central Iowa overnight through Wednesday morning." The Omaha office's watch, issued 3:09 p.m. CDT Tuesday for five southwest Iowa and ten southeast Nebraska counties, runs the same length. Two watches from the Topeka office, issued 6:52 p.m. CDT, cover 20 northeast Kansas counties until 5 a.m. CDT, and two from Kansas City, issued 2:42 p.m. CDT, cover 19 counties in northwest Missouri and the metro until 4:15 a.m. CDT.

The reason those watches exist is in the Des Moines discussion, and it is soil rather than sky. The office cited precipitable water values "around or above 2 inches," unseasonably high, with deep warm cloud depths for efficient rainfall, and National Water Model soil moisture at 50 to 90 percent of saturation in Iowa's bottom row of counties and generally above 80 percent north of that. Its phrase was "limited capacity."

Where the heaviest rain actually lands is a genuine disagreement between the models, and the office said so. Deterministic guidance put 2 to 5 inches over northern Missouri. The 12Z NAM and ECMWF put amounts like that over far southern Iowa instead. The 12Z HREF pushed the highest totals into Missouri, while the REFS ensemble kept a southern tier of Iowa counties in 2 to 4 inches. That is four ways of drawing the same rain, and the office left its watch where it was rather than pick one.

Looking past Wednesday, the office expects showers to go spotty and diminish through Wednesday afternoon and evening, then increase again after midnight into Thursday morning with 1 to at most 2 inches, amounts it described as not concerning except that they would fall on ground with no time to recover.

In the West, the flood watches ran to Wednesday morning: Grand Junction through 9:15 a.m. MDT for the San Juan Mountains, southeast Utah and the Canyonlands, plus a separate flash flood watch for the Central Yampa River Basin to 3 a.m. MDT; Salt Lake City to 3 a.m. MDT for the San Rafael Swell, Capitol Reef, Zion and Glen Canyon; Flagstaff to 7 a.m. MST for the Kaibab Plateau and Grand Canyon Country; Phoenix to 3 a.m. MST; and Albuquerque and El Paso through midnight MDT.

Severe weather was the quiet item. The Storm Prediction Center's day one outlook carried Marginal as its highest category, with a couple of severe storms possible from the southern High Plains to the southern Great Lakes, and two severe thunderstorm warnings from a single office were the national total on the wire. In the eastern Pacific, Tropical Depression Fifteen-E had 25 knot winds on the 21:00 UTC September 15 advisory. There were no tropical watches or warnings on United States soil.

The national board, for the nerds

Also on the board: flood warnings on the Withlacoochee River at US 41 Dunnellon in Citrus, Levy and Marion counties, Florida and on Horse Creek near Arcadia at SR 72 in DeSoto County, both minor flooding forecast from the Tampa Bay office; and a Fairbanks office flood watch issued 2:21 p.m. AKDT Tuesday for Two Rivers, the Fairbanks metro area and the Upper Kuskokwim Valley, running to 4 p.m. AKDT Wednesday.

Source: NWS active alerts and the SPC day one outlook text, both read at 1:31 a.m. UTC September 16, 2026. The SPC outlook's own issue time did not come through to this desk, so it is not stated; the category and summary are quoted as read. The tropical depression line is the 21:00 UTC September 15 advisory as carried on the wire; no position or pressure was available, so none is given. Yesterday's preliminary storm reports and the WPC excessive rainfall outlook were both unavailable to this desk, each returning HTTP 403.

This is a morning summary, not emergency information. For live warnings see weather.gov and your local officials. Iowa stream observations and forecasts are at weather.gov/desmoines/water, the page the Des Moines flood watch itself points to.

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The rock's live forecast for the places in this story

• Greenfield IA
• Stuart IA
• Adair IA
• Des Moines IA
• Red Oak IA
• Whiteriver AZ
• Chimayo NM
• Lubbock TX

Key points

• The federal disaster aid application, 211, and the emergency management agencies for Iowa, Utah, Arizona, New Mexico and Texas are gathered here for readers reached by this week's flooding.
• Every link below comes from the Weather Beat's standing verified aid list; nothing is added at press time.
• This is a summary of where to ask, not emergency information.

Where to get help: the Iowa and Southwest floods

This list accompanies today's brief, Iowa ran out of room for the rain, and canyon country had its own flood evening, which named flooding and flash flood warnings in Iowa, Utah, Arizona, New Mexico and Texas.

Apply for federal disaster aid. disasterassistance.gov is the federal government's own site to check whether a county has been declared for disaster assistance and to apply. It is for anyone in an affected area, not only those already declared.

Call 211. 211.org is the United Way's 211 line, reachable by call or text, for local aid referrals of any kind.

Iowa Homeland Security and Emergency Management. homelandsecurity.iowa.gov is Iowa's state emergency management agency, for readers in the Adair County and central Iowa flooding.

Utah Emergency Management. dem.utah.gov is Utah's state emergency management agency, for readers near the San Rafael Swell and the state's other flash flood warnings.

Arizona Department of Emergency and Military Affairs. dema.az.gov is Arizona's state emergency management agency, for readers in Gila, Navajo and Apache counties.

New Mexico Department of Homeland Security and Emergency Management. dhsem.nm.gov is New Mexico's state emergency management agency, for readers near the Frijoles burn scar flooding in Rio Arriba and Santa Fe counties.

Texas Division of Emergency Management. tdem.texas.gov is Texas's state emergency management agency, for readers on the South Plains flash flood warnings.

American Red Cross. The Red Cross get-help page lists shelters and emergency assistance, for anyone displaced by the flooding.

The Salvation Army. The Salvation Army's national site is a starting point for disaster relief support in an affected area.

SBA disaster loans. The SBA disaster assistance page covers loans for homeowners, renters and businesses, not businesses alone.

Ready.gov, floods. The Ready.gov floods page is the federal government's flood preparedness guidance.

NWS flood safety. The National Weather Service flood safety page is the Weather Service's own flood safety guidance.

This is a summary of where to ask, not emergency information. For live warnings see weather.gov and your local officials.

Key points

• Hurricane Lowell passed about 110 miles northwest of Lihue overnight with 105 mph sustained winds. As of the 2 a.m. HST advisory, a Hurricane Warning covered Kauai and Niihau and a Tropical Storm Warning covered Oahu.
• Lihue Airport measured a 75 mph gust, a flash flood warning ran overnight on Kauai, and the advisory forecast another 4 to 8 inches of rain there, with storm totals near 24 inches possible.
• On the mainland, Monday brought three preliminary tornado reports in Louisiana, North Dakota, and Nebraska, and today's Storm Prediction Center outlook carries a Slight Risk for central Iowa and far eastern Nebraska, mainly for wind.

Yesterday: Lowell came to Kauai's door

The story of the day happened in the dark, in the middle of the Pacific. Hurricane Lowell spent Monday night closing on the western end of the Hawaiian island chain, and by 11 p.m. HST the National Weather Service office in Honolulu described it as a high-end category 2 about 90 miles west of Lihue. Tropical-storm-force winds were widespread across Kauai by then, and stations on the island's leeward side between Waimea and Barking Sands had already gusted above hurricane force. The core passed to the west of Niihau and Kauai overnight rather than over them, which is the difference between a hard night and a catastrophe.

Kauai still took a beating. Lihue Airport reported sustained winds of 53 mph with a gust to 75 mph near the time of the 2 a.m. HST advisory. Heavy rain sent streams up across the island, and a flash flood warning ran overnight; when Honolulu forecasters extended it at 1:17 a.m. HST, radar showed the rain had ended over Kauai but gauges showed nearly every stream on the island still elevated from runoff, with flooding impacts ongoing in many locations. On Oahu, Daniel K. Inouye International Airport in Honolulu reported a gust of 43 mph.

The mainland had its own Monday. A tornado was reported in Hammond, Louisiana at 2:39 p.m. CDT, where it damaged trees and clipped a school building along a track of about three quarters of a mile. A brief cone tornado was reported near Strawberry Lake, North Dakota at 6:35 p.m. CDT, and a storm chaser reported a third near Spencer, Nebraska at 7:35 p.m. CDT. Around those, a broad ribbon of wind damage stretched from Montana and the Dakotas down through Nebraska to the Gulf Coast parishes of Louisiana, with trees and power lines down from Slaughter to Thomasville.

Lowell, measured

Source: CPHC/NHC Hurricane Lowell Intermediate Advisory 49A, issued 2:00 a.m. HST (1200 UTC) Tuesday, September 8, with position fixed by an Air Force Reserve Hurricane Hunter aircraft.

Mainland storm reports, September 7

Source: Storm Prediction Center storm reports for the 12Z September 7 to 12Z September 8 day. All counts and values are preliminary.

Today, officially

Lowell first. As of the 2 a.m. HST advisory, the forecast took the core farther from Kauai County through today, then bent it northwest and west, slowing and weakening, after it clears the main islands. The rain is not done: the advisory forecast an additional 4 to 8 inches on Kauai with maximum storm totals of 24 inches possible, 3 to 8 more inches on the Big Island, and 2 to 5 more on Oahu and Maui County, with significant flash flooding and mudslides possible, especially on Kauai and parts of the Big Island. Storm surge of 2 to 4 feet was forecast for Kauai County, highest along Kauai's south coast and on Niihau, with up to 1 foot on Oahu. The advisory also said several tornadoes were possible near Kauai and Niihau through the overnight period, and that swells from Lowell would keep surf and rip currents life-threatening across many of the islands for the next few days. A statewide flood watch and high surf warnings were in effect overnight, and the 11:06 p.m. HST forecast discussion put it plainly: "High surf and heavy rain will impact all islands with strong winds mainly impacting the western end of the state." The same discussion noted the separate east-shore swell came from former Tropical Storm Karina, now a post-tropical low. The next complete Lowell advisory was scheduled for 5 a.m. HST. If you are in Hawaii, preparedness guidance lives at ready.gov and the Hawaii Emergency Management Agency.

On the mainland, the Storm Prediction Center's 1300 UTC Day 1 outlook, issued 7:31 a.m. CDT, carries a Slight Risk of severe thunderstorms over portions of central Iowa and far eastern Nebraska. The outlook expects widely scattered severe storms Tuesday afternoon and evening, mainly for damaging wind gusts, as a cold front works into a moderately to strongly unstable air mass, with more sporadic severe wind and large hail possible from the upper Midwest into the central Plains and a lower-end wind threat spreading into western Kansas in the evening.

Heat is still on the September map. Extreme heat warnings were in effect Tuesday morning from forecast offices in San Diego, Phoenix, and Las Vegas across the desert Southwest, and from Kansas City, Topeka, Springfield, and Tulsa across the southern Plains into western Missouri.

Out in the East Pacific, Tropical Storm Marie held 45 mph winds about 760 miles southwest of San Diego as of the 2 a.m. PDT advisory, moving west-northwest at 8 mph with no coastal watches or warnings in effect. The National Hurricane Center forecast steady weakening to a post-tropical remnant low later today or Wednesday, while its swell keeps beach conditions dangerous along the Baja California peninsula and Southern California for the next couple of days.

This is a morning summary, not emergency information. For live warnings see weather.gov and your local officials.

The rock's live forecast for the places in this story

• Lihue HI
• Waimea HI
• Honolulu HI
• Hammond LA
• Spencer NE
• Fort Pierre SD
• Trenton NE
• Armour SD
• Butte NE
• Slaughter LA
• Thomasville AL

Key points

• Kauai and Niihau are under a Hurricane Warning as of 11 p.m. HST Sunday, upgraded from a tropical storm warning after Lowell's track shifted east again. At 2 a.m. HST Monday the category 3 hurricane was 415 miles southwest of Lihue HI with 115 mph winds, its rainbands already spreading over Kauai and Oahu, and its center is forecast to pass just west of Kauai County late today into early Tuesday.
• Sunday was quieter on the mainland: 141 preliminary wind reports, less than half of Saturday's count, but Montana ran a hail night with stones reported to 3 inches and windows broken out near Shepherd MT, and a storm chaser reported a brief tornado touchdown in western North Dakota, the first preliminary tornado report after two straight days without one.
• As of this morning's products: a Slight Risk of severe storms over North Dakota and southeast South Dakota into northeast Nebraska, mainly for large hail; Flood Watches across northwest and north central Montana through Tuesday morning; and Extreme Heat Warnings around Kansas City and Topeka running through Tuesday evening.

Yesterday

The Southeast's wind streak reached a fourth day, but it is finally shrinking. After Saturday's 340 reports, Sunday produced 141 nationwide, and the center of gravity stayed in South Carolina, which logged 50 of them, more than the next three states combined. The strongest was familiar ground: an NWS employee near Red Bank SC estimated gusts of 65 to 70 mph with small hail at 6:08 p.m. EDT, the same community where a trained spotter clocked 65 mph on Saturday. Georgia added 21 reports, and North Carolina, Saturday's leader with 138, fell to 9.

The bigger story was Montana, and it played out in two acts. The first came Sunday evening in the center of the state. Hail 3 inches in diameter was reported 5 miles north of Hilger MT at 9:25 p.m. MDT, confirmed with a photo from the public per the Great Falls office, with tennis ball hail estimated near Moccasin MT at 8:45 p.m. MDT and 2 inch hail at Danvers MT the same minute. The second act came after midnight near Billings: numerous public reports of hail around 2 inches at Shepherd MT at 2:30 a.m. MDT Monday, with windows broken out. Montana's 11 hail reports led the country.

The night storms carried wind too. A mesonet station 8 miles south of Sibley Peak WY measured 73 mph at 9:18 p.m. MDT, the day's strongest gust anywhere. The Rapid City SD airport measured 67 mph at 1:05 a.m. MDT Monday, and the Baker MT airport station matched it at 2:00 a.m. MDT.

And after two days without one, the country produced a single preliminary tornado report. A storm chaser reported a brief touchdown 8 miles south-southwest of Arnegard ND at 7:17 p.m. CDT Sunday, per the Bismarck office, which notes the location is radar estimated.

Largest measured gusts, September 6 into early September 7:

Largest hail:

Report counts for the day: 141 wind, 27 hail, 1 tornado. Wind reports by state: South Carolina 50, Georgia 21, Missouri 12, North Carolina 9, Florida 7, Mississippi 7, Kansas 6, Alabama 6, Arkansas 5, Montana 3, and 15 more spread across North Dakota, Louisiana, Colorado, Wyoming, South Dakota, Texas, Oklahoma, Iowa, Utah, and Minnesota. Hail reports: Montana 11, North Dakota 4, South Carolina 4, Kansas 3, Iowa 2, and one each in Minnesota, North Carolina, and Missouri.

Source: Storm Prediction Center preliminary storm reports for the 24 hours ending 8 a.m. EDT September 7. All counts, sizes, and gusts are preliminary and subject to revision.

Today, officially

Lowell and Hawaii

The warning got stronger overnight. Per Central Pacific Hurricane Center advisory 45, issued 11 p.m. HST Sunday, September 6, a Hurricane Warning is now in effect for Kauai County, including the islands of Kauai and Niihau, replacing the tropical storm warning that stood through the weekend. The accompanying discussion states the reason plainly: "Given another eastward shift in the track guidance and the forecast close approach of hurricane-force winds to Niihau, a Hurricane Warning has been issued for Kauai County." A Hurricane Warning also remains in effect for the Papahanaumokuakea Marine National Monument from Nihoa to French Frigate Shoals.

Per intermediate advisory 45A, issued 2 a.m. HST Monday, the center of Hurricane Lowell was about 415 miles southwest of Lihue HI and 445 miles southwest of Honolulu HI, with maximum sustained winds of 115 mph, a category 3, and a central pressure of 950 mb. Lowell was moving north-northeast at 10 mph, and rainbands from the storm were already spreading over Kauai and Oahu at advisory time. On the forecast track the center crosses portions of the marine monument, just west of the main Hawaiian Islands, tonight. Hurricane conditions are expected in Kauai County beginning this afternoon or evening, per the advisory, and the discussion's key message puts the pass "late Monday into early Tuesday." An Air Force Reserve Hurricane Hunter aircraft found the storm holding multiple concentric wind maxima around the eye overnight, with the central pressure slowly rising; gradual weakening is expected, but the forecast keeps Lowell a hurricane through its closest approach.

The rain arrived ahead of the wind. The Honolulu office reissued its Flood Watch for all Hawaiian islands at 3:12 a.m. HST Monday, running through 6 p.m. HST Tuesday, with the watch text noting that moisture along Lowell's eastern flank will bring periods of heavy rain through Tuesday. The advisory forecasts additional rainfall of 6 to 10 inches for Kauai with maximum totals of 14 inches possible, 4 to 8 inches for the Big Island with isolated totals of 12, 4 to 6 inches for Oahu with isolated 8, and 2 to 4 inches for Maui, rain that "may produce significant flash flooding and mudslides, especially across Kauai county and portions of the Big Island." Storm surge of 1 to 3 feet is possible in Kauai County and up to 1 foot on Oahu if the peak surge arrives at high tide. Several tornadoes are possible near Kauai and Niihau this afternoon through tonight, per the advisory, with a few possible across the remaining islands.

The surf is its own hazard. A High Surf Warning issued 2:44 p.m. HST Sunday covers south facing shores of all islands plus west facing shores of the Big Island through 6 a.m. HST Tuesday, and the Honolulu forecast discussion, issued 11:15 p.m. HST Sunday, expects the south swell from Lowell to rise rapidly today and peak tonight. The discussion adds a specific worry: "Coinciding also with the peak monthly afternoon high tides, this could bring the potential for significant damage to coastal properties and infrastructure, including roadways to portions of Kauai and possibly Oahu." On the water, a Hurricane Warning covers the offshore waters west of Kauai County and Tropical Storm Warnings cover the Kauai Channel and Kauai windward waters, per the same discussion, which also notes that any deviation in track in the next 24 hours would make a significant difference for the waters around Kauai County.

If you are in Kauai County, preparations should be rushed to completion, in the advisory's own words. Official preparedness guidance is at ready.gov, and the Hawaii Emergency Management Agency is at dod.hawaii.gov/hiema.

Advisory vitals, Lowell:

Source: CPHC Hurricane Lowell intermediate advisory 45A, issued 2 a.m. HST September 7; discussion 45, issued 11 p.m. HST September 6; NWS Honolulu forecast discussion, issued 11:15 p.m. HST September 6.

Severe storms, northern Plains

The Storm Prediction Center's Day 1 outlook, issued 7:44 a.m. CDT Monday, carries a Slight Risk over portions of North Dakota and from southeast South Dakota into northeast Nebraska. Its summary reads: "Widely scattered severe storms capable of mainly large hail are expected over portions of North Dakota as well as southeast South Dakota into northeast Nebraska this afternoon into evening." The setup is a deep upper trough over the western United States with a surface low over east central Montana, and the outlook notes that along one boundary near the North Dakota border, "any storms that develop should become supercells capable of all severe hazards, including very large hail and a brief tornado." A broader area of isolated hail and wind risk covers the northern and central Plains into the upper Mississippi Valley, with locally damaging gusts possible along the central Gulf Coast this afternoon and evening.

Montana rain

The same trough that hailed on Montana Sunday night is now a flood concern. The Weather Prediction Center's Day 1 excessive rainfall outlook, issued 4:15 a.m. EDT Monday, places a Slight Risk over northwest and north central Montana, and two forecast offices have Flood Watches running through noon MDT Tuesday: the Great Falls office, issued 6:01 a.m. MDT, for the East Glacier Park region, the Rocky Mountain Front, and the high plains east of the mountains, and the Missoula office, issued 3:59 a.m. MDT, for the West Glacier region, the Flathead and Mission valleys, and the Potomac and Seeley Lake region. Both watches say flooding caused by excessive rainfall continues to be possible, with excessive runoff able to flood creeks, streams, and low-lying areas.

Heat, middle of the country and Puerto Rico

Extreme Heat Warnings from the Kansas City office, issued 3:55 a.m. CDT, and the Topeka office, issued 2:13 a.m. CDT, run through Tuesday evening, September 8, for the Kansas City metro, west central Missouri, and much of east and northeast Kansas, with heat index values in excess of 105 per the Kansas City product and 100 to 107 per Topeka's. The Springfield MO office's warning, covering southwest Missouri and southeast Kansas with heat index up to 105, ends at 8 p.m. CDT tonight. In Puerto Rico, an Extreme Heat Warning issued 10:03 a.m. AST covers most of the island until 5 p.m. AST today. And the desert Southwest is next in line: the Phoenix office issued Extreme Heat Warnings at 12:33 a.m. MST Monday that begin Tuesday morning for the Phoenix metro, Yuma, and the lower Colorado River valley, with afternoon temperatures of 104 to 112 forecast into Thursday and Friday. None of the products states a covered population figure.

One reading from the other end of the thermometer: a Freeze Warning from the Medford OR office, issued Sunday morning, expired at 9 a.m. PDT this morning for the Klamath Basin and surrounding high country of southern Oregon and northeast California, including Klamath Falls OR, with lows as cold as 29 degrees. The same national map held a freeze warning and a 110 heat index at once. September does this.

Southeast Texas rivers

Two river warnings remain from Edouard's rain. Per the Lake Charles office's Flood Warning issued 8:11 p.m. CDT Sunday, Pine Island Bayou near Sour Lake TX, affecting Hardin and Jefferson counties, is warned until early Wednesday morning, and the Neches River at the saltwater barrier, affecting Hardin, Jefferson, Jasper, and Orange counties, until Wednesday night. The warning for Village Creek near Kountze TX was cancelled with the same product.

The rest of the tropics

Tropical Storm Marie, per NHC advisory 25 issued 2 a.m. PDT Monday, was about 580 miles west-southwest of Punta Eugenia, Mexico with 65 mph winds, weakening, and forecast to become a post-tropical remnant low Tuesday night or early Wednesday. The advisory headline notes the storm is expected to continue producing dangerous beach conditions along the coasts of Baja California and southern California for the next several days; there are no coastal watches or warnings. Former Tropical Storm Karina is now a post-tropical low northeast of Hawaii, per the Honolulu forecast discussion, and its leftover east swell is still contributing to a High Surf Advisory on east facing Hawaiian shores. The Atlantic has no active storms on the NHC board this morning.

This is a morning summary, not emergency information. For live warnings see weather.gov and your local officials.

The rock's live forecast for the places in this story

• Lihue HI
• Honolulu HI
• Red Bank SC
• Lexington SC
• Hilger MT
• Moccasin MT
• Danvers MT
• Shepherd MT
• Baker MT
• Arnegard ND
• Rapid City SD
• Dumas TX
• El Dorado Springs MO
• Kansas City MO
• Topeka KS
• Springfield MO
• Phoenix AZ
• Yuma AZ
• Klamath Falls OR
• Sour Lake TX
• Kountze TX

Key points

• A Tropical Storm Warning is in effect for Kauai and Niihau as of the 5 a.m. HST advisory Sunday. Hurricane Lowell, a category 3 with 125 mph winds about 580 miles south-southwest of Lihue HI, is forecast to pass 100 to 200 miles west of Kauai Monday night, and a Flood Watch covers every island from noon Sunday through Tuesday evening.
• Saturday was the busiest wind day of the stretch: 340 preliminary wind reports nationwide, nearly double Friday's 173, and again not one tornado report. The Carolinas took 232 of them, one person was injured by trees falling on homes near Rogersville TN, and a western Nebraska storm gusted to 83 mph at Kingsley Dam just after midnight.
• As of this morning's products: a Slight Risk of severe storms over the southern Appalachians into the Savannah River valley and another over western and central Montana, Kansas City and Topeka Extreme Heat Warnings running through Tuesday evening, and the southeast Texas river flood warnings now down to four counties.

Yesterday

For the third day in a row the East's afternoon storms put trees down, and for the third day the damage moved south. Thursday it was Pennsylvania to Virginia, Friday it was Virginia and the mountains, and Saturday the Carolinas took the most of it: 138 wind reports in North Carolina and 94 in South Carolina, the two highest state counts in the country.

The day's one reported injury came before the Carolinas even got going. At 11:50 a.m. EDT on September 5, storm winds near Rogersville TN dropped trees onto several homes between Rogersville and the community of Persia, injuring one person, per the Morristown office's report. Three hours later and one state over, photos from McMinnville TN showed the roof of one building peeled off and blown into the restaurant next door at 3:35 p.m. CDT.

Then the Piedmont's turn. Asheboro NC logged four separate tree-on-house reports in a seven minute span starting at 3:11 p.m. EDT, plus a tree and power lines down on a car with a person inside on Farmer Road, no injuries. At 3:35 p.m. EDT the Chatham County 911 center had at least two dozen reports of trees down in Siler City NC, a few of them on homes. The day's strongest East Coast gust, 72 mph, was measured at the Fayetteville airport east of Hope Mills NC at 4:48 p.m. EDT, and Pope Army Airfield measured 64 mph seven minutes later. In South Carolina a trained spotter near Red Bank SC clocked gusts of 55 to 65 mph between 5:40 and 5:45 p.m. EDT, a large tree came down on a house near Blacksburg SC at 3:05 p.m. EDT, and a porch lost its roof near Williamston SC. Georgia added 36 reports, including a large tree onto vehicles in Hall County at 5:15 p.m. EDT.

Hail stayed mostly small in the East: quarter to golf ball size at Fort Barnwell NC at 5:15 p.m. EDT, and 2 inch hail near Flowers in Johnston County at 4:15 p.m. EDT.

The Plains ran their own storm, and it lasted all night. Trained spotters around Alliance NE reported 2 to 2.5 inch hail starting at 4:01 p.m. MDT, with hail accumulating on the ground by early evening. The wind followed: 64 mph east of Bridgeport NE at 6:18 p.m. MDT, 66 mph at the Alliance airport station at 7:24 p.m., 65 mph at a personal weather station near Lorenzo at 9:22 p.m. Then, just after midnight, the storms crossing Keith County hit their peak: 76 mph at a station near Kingsley Dam at 11:57 p.m. MDT, 83 mph on a Union Pacific sensor northeast of the dam at 12:10 a.m. MDT Sunday, and 78 mph west of Paxton NE five minutes later.

Largest measured gusts, September 5 into early September 6:

Report counts for the day: 340 wind, 31 hail, 0 tornado. Wind reports by state: North Carolina 138, South Carolina 94, Georgia 36, Nebraska 17, Virginia 14, Tennessee 12, Kentucky 7, West Virginia 5, Alabama 5, Missouri 4, Texas 2, and one each in Colorado, Florida, Illinois, Indiana, Louisiana, and New Mexico. Hail reports: North Carolina 12, Nebraska 12, North Dakota 3, and one each in Colorado, Kentucky, South Carolina, and South Dakota. Largest hail: 2.5 inches, 5 miles west-northwest of Alliance NE.

Source: Storm Prediction Center preliminary storm reports for the 24 hours ending 8 a.m. EDT September 6. All counts and gusts are preliminary and subject to revision.

Today, officially

Lowell and Hawaii

The waiting phase ended overnight. Per Central Pacific Hurricane Center advisory 42, issued 5 a.m. HST Sunday, September 6, a Tropical Storm Warning is now in effect for Kauai County, including the islands of Kauai and Niihau, and a Hurricane Warning is in effect for the Papahanaumokuakea Marine National Monument from Nihoa to French Frigate Shoals. At advisory time the center of Hurricane Lowell was about 580 miles south-southwest of Lihue HI and 600 miles southwest of Honolulu HI, with maximum sustained winds of 125 mph, a category 3, and a central pressure of 943 mb. Lowell was moving north-northwest at 6 mph, and the advisory forecasts "a turn toward the north and north-northeast with an increase in forward speed" over the next couple of days, "bringing the center of Lowell across portions of the Papahanaumokuakea Marine National Monument, just west of the main Hawaiian Islands, Monday night." The advisory expects Lowell to remain a major hurricane through Monday, with gradual weakening beginning tonight.

The Honolulu forecast discussion, issued 5:01 a.m. HST Sunday, puts the pass this way: "Lowell is forecast to pass 100 to 200 miles west of Kauai, and will bring several hazards to the state. The main hazards are expected to be flash flooding, strong winds, and high surf." One bookkeeping note: that discussion still refers to a Tropical Storm watch for Kauai and Niihau; the warning products issued ten minutes earlier and the 5 a.m. advisory both carry the warning, so the discussion's wording simply lags the upgrade.

The rain is not waiting for the storm. The same discussion reports that moisture "has already increased across the area more than forecast," with several windward areas picking up over 1.5 inches in six hours Sunday morning, and the office moved the start of its Flood Watch up from 6 p.m. to noon HST Sunday. The watch covers every island through 6 p.m. HST Tuesday. The advisory's rainfall forecast: 6 to 10 inches for Kauai with maximum totals of 14 inches possible, 4 to 8 inches for the Big Island with isolated totals of 12, 2 to 4 inches for Maui with isolated 8, and 2 to 4 inches elsewhere, rain that "may produce significant flash flooding and mudslides, especially across Kauai County and portions of the Big Island." Storm surge of 1 to 3 feet is possible in Kauai County and up to 1 foot on Oahu if the peak surge arrives at high tide, and swells are "likely to cause life-threatening surf and rip current conditions during the next several days across many of the Hawaiian islands." A High Surf Advisory issued 4:17 a.m. HST runs through 6 a.m. HST Tuesday. The discussion also flags a threat of short-lived tornadoes and waterspouts embedded in rainbands, mainly near Kauai and Niihau, as Lowell makes its closest approach Monday night into early Tuesday.

Tropical storm conditions are expected in Kauai County by Monday afternoon or evening, per the advisory. If you are in Hawaii, today is the day to finish preparations. Official preparedness guidance is at ready.gov, and the Hawaii Emergency Management Agency is at dod.hawaii.gov/hiema.

Advisory vitals, Lowell:

Source: CPHC Hurricane Lowell advisory 42 and NWS Honolulu forecast discussion, both issued 5 a.m. HST September 6.

Severe storms, Southeast and Montana

The Storm Prediction Center's Day 1 outlook, issued 7:51 a.m. CDT Sunday, carries two Slight Risk areas. Its summary reads: "Widely scattered damaging wind gusts are likely across portions of the Southeast this afternoon and early evening. Widely scattered large hail occurrences are expected across portions of western and central Montana this afternoon and evening." The Southeast area runs from the southern Appalachians into the Savannah River valley, the same general country that spent Saturday picking up tree damage; the outlook expects storms in a hot, moist airmass with weak shear, favoring gusty multicells and line segments over anything organized. The outlook also tracks the overnight Nebraska storm complex, noting "a linear MCS continues to push eastward across the central Plains this morning" with new development in south-central and southeast South Dakota and adjacent northeast Nebraska, and it holds isolated severe risk from the eastern Dakotas and western Minnesota into the Ozark Plateau and Gulf Coast states.

The Weather Prediction Center's Day 1 excessive rainfall outlook, issued 4:04 a.m. EDT, places Slight Risk areas over the western Carolinas and Georgia into north Florida, from southeast South Dakota and southwest Minnesota into western Iowa, eastern Nebraska, and northwest Missouri, and over the Great Basin from southern Nevada across southern Utah.

Heat around Kansas City

The mid-Mississippi Valley heat is on its last widespread day, but not everywhere. Extreme Heat Warnings from the Kansas City office, issued 3:39 a.m. CDT, and the Topeka office, issued 1:50 a.m. CDT, run through Tuesday evening, September 8, for the Kansas City metro and east-central Kansas, with heat index values in excess of 105 per the Kansas City product and 100 to 108 per Topeka's. Warnings covering the rest of west-central Missouri, the Springfield MO area (heat index up to 107), west-central Arkansas per the Tulsa office (up to 112), and Puerto Rico end this evening. None of the products states a covered population figure.

Southeast Texas rivers

The tail of Edouard is down to four counties. Per the Lake Charles office's Flood Warning issued 8:16 p.m. CDT Saturday, Village Creek near Kountze TX is warned until early Monday, Pine Island Bayou near Sour Lake TX until Monday night, and the Neches River at the saltwater barrier, covering Hardin, Jefferson, Jasper, and Orange counties, until early Wednesday.

The rest of the tropics

The other two storms are winding down far from land. Tropical Storm Karina, per CPHC advisory 41 issued 5 a.m. HST Sunday, was about 680 miles east-northeast of Hilo HI with 60 mph winds, forecast to become a post-tropical gale by late tonight. Hurricane Marie, per NHC advisory 22 issued 8 a.m. PDT Sunday, was about 800 miles west of the southern tip of Baja California with 80 mph winds, weakening, with the advisory headline noting dangerous beach conditions along the coasts of Baja California and southern California for another couple of days. Neither has watches or warnings. The Atlantic has no active storms on the NHC board this morning.

This is a morning summary, not emergency information. For live warnings see weather.gov and your local officials.

The rock's live forecast for the places in this story

• Lihue HI
• Honolulu HI
• Hilo HI
• Rogersville TN
• McMinnville TN
• Asheboro NC
• Siler City NC
• Hope Mills NC
• Fort Barnwell NC
• Red Bank SC
• Blacksburg SC
• Williamston SC
• Alliance NE
• Bridgeport NE
• Paxton NE
• Kansas City MO
• Topeka KS
• Springfield MO
• Kountze TX
• Sour Lake TX

On the evening of September 5, the showers over Connecticut moved from north to south. For this part of the world that is the wrong direction. Most of the year our weather rides a wind from the west or southwest, so a storm that crosses the state usually arrives from Pennsylvania or the Hudson Valley and leaves toward Rhode Island and the ocean. On Saturday night the showers came down out of New Hampshire and Massachusetts, crossed Connecticut heading south-southeast, and continued toward Long Island. Someone who has watched this sky for decades told us he had never seen it. Here is what did it, from the National Weather Service's own analyses and discussions, and from our radar and wind data.

What happened, measured

Our storm-motion tool reads consecutive radar frames and measures how the echoes shift. At 8 PM, over Oakville in Litchfield County, it measured the cells moving toward the south-southeast, 166 to 169 degrees on the compass, at 14 to 17 mph, frame after frame, with a confidence of about 0.7 on each pair. That is the number behind the impression: the rain was heading south.

The forecasters saw it coming. The New York office wrote at 8:04 PM that showers would develop "across eastern CT and eastern LI before tracking south and west tonight." The Boston office, at 7:49 PM, described "wrap-around moisture in northeast flow across much of New England."

The setup at 8 PM

Three things were in place at the same time, and each one pushed in the same direction.

A closed low aloft, parked to the northeast. The New York office's discussion put it plainly: "An upper low over the Canadian Maritimes will remain nearly stationary through Sunday, sending a series of shortwaves south across the Northeast." Boston called it "slow-moving, closed mid/upper low pressure over the Canada Maritimes" inside "a broad cyclonic mid-level flow." Air circles a low counterclockwise. On the western side of a low that sits over the Maritimes, that circulation runs from north to south, straight across New England. Storm cells travel with the wind a mile or two above the ground, so a cell born over New Hampshire went south.

The Storm Prediction Center's 500 mb chart for that hour shows the flow directly: over New England the winds at roughly 18,000 feet are out of the north and northwest, and the heights run 573 to 579 decameters, low for early September. The low itself sits just off the chart to the northeast.

High pressure to the north and west, low pressure to the south and east. At the surface, the Weather Prediction Center's analysis for the same hour draws high pressure of 1020 to 1021 millibars over the Great Lakes and Quebec, and a cold front along the Mid-Atlantic coast with low pressure on it. Air moves from high pressure toward low, bent to the right in the northern hemisphere, and that gradient sets a surface wind from the north and northeast over the region.

Our own wind field, drawn from the NOAA URMA 2.5 km analysis we keep on our server, shows what that looked like on the ground. Over interior New York and Pennsylvania the arrows point south. Over the waters off New England and the Mid-Atlantic they point south and southwest, strongest offshore. Over Connecticut itself the surface wind was light, about 6 mph in the analysis, because the push was aloft and out over the water; the state sat under the flow rather than in it.

A front and its troughs offshore. The Ocean Prediction Center's forecast for the Mid-Atlantic waters that afternoon had "a slow-moving cold front" reaching the central waters and "a series of low pressure troughs" sliding southeast over the northern waters through Monday. That is where the showers were going. On radar it looks as if something off the Virginia and Delaware coast is drawing the weather toward it, and in a sense it was: the front was the low side of the gradient, and the troughs riding down the flow gave the showers a place to go.

Why it feels so strange

None of these pieces is exotic. Cutoff lows, northeast flow behind a coastal front, wraparound showers: every forecaster in the Northeast has a name for each of them. What is uncommon is the combination sitting over southern New England long enough, in early September, for the showers themselves to travel north to south across a whole state. Our forecasting doctrine treats storm motion as physics: a cell keeps going the way the wind aloft is taking it until it dies. Saturday the wind aloft came from the north, so the cells did too.

How rare is it? Honestly, we do not know yet, and we are not going to guess. We are building the count: storm-motion direction over Connecticut for every storm day from 2010 through 2026, from the archived radar, with the number of storm days each year beside it, plus the direction of the wind aloft over the state year by year from the reanalysis record. If north-to-south days have grown, the count will show it. If they have always been this rare, it will show that too.

What the science says about the jet stream

The question everyone asks is whether the jet stream has changed. Some of that is settled and some is argued, and the piece should say which is which.

Settled, in the peer-reviewed record: the jet streams have moved. Archer and Caldeira, writing in Geophysical Research Letters in 2008, analyzed two reanalysis datasets for 1979 to 2001 and found that "the jet streams have risen in altitude and moved poleward in both hemispheres," and that "in the northern hemisphere, the jet stream weakened." They added that further work was needed to attribute the causes.

Argued: whether a warming Arctic is making the jet wavier and blocking patterns, the stalled lows and highs, more common. Francis and Vavrus, in the same journal in 2012, identified two effects of Arctic warming that "each contribute to a slower eastward progression of Rossby waves in the upper-level flow: weakened zonal winds, and increased wave amplitude." Barnes, in 2013, reexamined that evidence across three reanalyses and reported that "the frequency of blocking occurrence exhibits no significant increase in any season." Both are careful papers, and they disagree. A slower, wavier jet would make a night like Saturday more likely. Whether the record shows that yet is the open question, and no paper we have read dates a change to any single year.

So the honest headline is the one at the top. A stationary low to the northeast, high pressure to the northwest, and a front offshore turned the wind around, and the weather followed it south. The jet stream set the stage, as it always does. Whether it is setting this stage more often than it used to is a question for the count, and we will publish the count.

Where these numbers come from

- Storm motion over Oakville: our own radar frames, cross-correlated frame to frame by myweatherrock's storm-motion tool, 8 PM EDT September 5.

- Radar loop: NOAA MRMS merged reflectivity composite, 20Z September 5 to 04Z September 6, rendered by myweatherrock.

- Wind field: NOAA URMA 2.5 km analysis for 00Z September 6, from the copy myweatherrock keeps for grading its forecasts.

- Surface analysis: NOAA Weather Prediction Center, 00Z September 6, 2026.

- 500 mb analysis: NOAA Storm Prediction Center upper-air chart, 00Z September 6, 2026.

- Forecast discussions: NWS New York (8:04 PM EDT September 5), NWS Boston (7:49 PM EDT), and the NWS Ocean Prediction Center Mid-Atlantic offshore forecast (5:09 PM EDT), quoted as issued.

- Papers: Archer and Caldeira, "Historical trends in the jet streams," Geophysical Research Letters, 2008 (doi 10.1029/2008GL033614); Francis and Vavrus, "Evidence linking Arctic amplification to extreme weather in mid-latitudes," Geophysical Research Letters, 2012 (doi 10.1029/2012GL051000); Barnes, "Revisiting the evidence linking Arctic amplification to extreme weather in midlatitudes," Geophysical Research Letters, 2013 (doi 10.1002/grl.50880). Quotations are from the published abstracts.

Key points

• As of the 11 p.m. HST advisory Friday, Hurricane Lowell was a category 4 with 155 mph winds about 610 miles south-southwest of Honolulu HI. No watches are in effect, but the Central Pacific Hurricane Center says watches could be required for the westernmost Hawaiian Islands on Saturday, and the Honolulu forecast office puts the closest approach near Kauai County Monday night.
• Friday was another wind day in the East, the second in a row: 173 preliminary wind reports nationwide, 66 of them in Virginia, and not a single tornado report anywhere in the country. The day's biggest measured gust, 81 mph, came from a separate storm near Aspermont TX.
• As of this morning's products: a Slight Risk of severe storms from the Ohio Valley into the Carolinas, Extreme Heat Warnings across six mid-Mississippi Valley states with the Kansas City and Topeka warnings running into Tuesday, and southeast Texas rivers still under flood warnings across six counties.

Yesterday

The front that spent Thursday dropping trees from Pennsylvania to Virginia kept working Friday, one tier of states farther south. The first calls came just after lunch in far western Maryland, where the Friendsville MD area logged about half a dozen reports of trees and wires down starting at 1:05 p.m. EDT on September 4. Through the afternoon the reports spread across southeast Ohio and West Virginia, a tree into a power line in Parkersburg WV at 1:30 p.m. EDT, and around 400 customers without power near Hamden OH.

Virginia took the evening shift, and took the most of it: 66 wind reports, the highest count of any state. Rockingham County lost trees onto power lines in Elkton VA and along McGaheysville Road, and in Lexington VA at 5:58 p.m. EDT, storm winds blew down six trees that landed on multiple power lines and three vehicles. Out on the coastal plain, a metal roof was blown off a house in Elizabeth City NC at 3:44 p.m. EDT. North Carolina's reports ran from mid-afternoon in the foothills near North Wilkesboro NC, where one downed tree fell on a vehicle with no injuries, to power outages in Nash and Edgecombe counties around 8:30 p.m. EDT.

The day never really closed. Before sunrise Saturday a new complex of storms was putting trees down across southeast Ohio and western West Virginia, with reports as late as 7:20 a.m. EDT, and 400 customers lost power near Elizabeth WV at 7 a.m. In Logan County OH, the Wilmington OH office's Flash Flood Warning, extended at 5:55 a.m. EDT Saturday, stated that local law enforcement had reported flash flooding after 3.5 to 4 inches of rain fell.

The Plains had their own, unrelated wind. The strongest measured gust in the country, 81 mph, hit 3 miles northeast of Aspermont TX at 4:59 p.m. CDT, with additional 70 to 72 mph gusts measured in the minutes before it. Overnight, a station near Guymon OK in the Oklahoma panhandle measured 77 mph at 12:50 a.m. CDT, and early Saturday morning gusts of 60 and 61 mph were measured in Holt County NE and near Dimock SD.

Hail was scarce and small. Seven reports all day, the largest a golf ball, 1.75 inches, 3 miles northwest of Parkersburg IA at 3:28 p.m. CDT, with ping pong ball hail in Madison and Orange counties in Virginia during the mid-afternoon.

Largest measured gusts, September 4 into early September 5:

Report counts for the day: 173 wind, 7 hail, 0 tornado. Wind reports by state: Virginia 66, North Carolina 32, West Virginia 31, Ohio 23, Indiana 5, Maryland 4, Kentucky 3, Iowa 2, and one each in Alabama, Nebraska, Oklahoma, South Dakota, Tennessee, Texas, and Wisconsin. Hail reports: Virginia 4, Iowa 2, North Carolina 1.

Source: Storm Prediction Center preliminary storm reports for the 24 hours ending 8 a.m. EDT September 5. All counts and gusts are preliminary and subject to revision.

Today, officially

Hurricane Lowell and Hawaii

Lowell is the story of the weekend, and it is still days away. Per Central Pacific Hurricane Center advisory 37, issued 11 p.m. HST Friday, September 4, the eye of Hurricane Lowell was about 610 miles south-southwest of Honolulu HI and 625 miles south-southwest of Lihue HI, with maximum sustained winds of 155 mph measured by Air Force Hurricane Hunter aircraft and a central pressure of 925 mb. The advisory headline reads that Lowell "weakens slightly and is now a category 4 hurricane." It was moving west at 7 mph, and the advisory forecasts a gradual slowdown over the next day or so, followed by a sharp turn to the north or north-northeast on Sunday.

There are no coastal watches or warnings in effect. The advisory states that "watches could be required for portions of the westernmost Hawaiian Islands on Saturday."

The Honolulu forecast discussion, issued 8:20 p.m. HST Friday, reads: "Hurricane Lowell is forecast to move close to Kauai County Monday night as a category 2 to 3 hurricane. Weather impacts such as high surf and heavy rain are forecast to extend hundreds of miles from the center of Hurricane Lowell, potentially impacting any of the islands." The same discussion notes that "any deviation eastward from its forecast track could bring more severe wind impacts especially to Kauai County," and that as of Friday night it was "currently too early for tropical watches and warnings tonight, but will be discussed and determined soon."

The advisory's stated land hazards: rainfall totals of 3 to 6 inches for Kauai and the Big Island, with maximum totals exceeding 10 inches possible, 2 to 4 inches for Maui with isolated 8 inch totals possible, and 1 to 2 inches elsewhere, rain that "may produce flash flooding and mudslides, especially in areas of steep terrain." Swells are "likely to cause life-threatening surf and rip current conditions during the next several days across many of the Hawaiian islands."

If you are in Hawaii, this weekend is the time to check supplies and plans, not Monday. Official preparedness guidance is at ready.gov, and the Hawaii Emergency Management Agency is at dod.hawaii.gov/hiema.

Advisory vitals, Lowell:

Source: CPHC Hurricane Lowell advisory 37 and NWS Honolulu forecast discussion, both issued the evening of September 4 HST.

Severe storms, Ohio Valley to the Carolinas

The Storm Prediction Center's Day 1 outlook, issued 7:54 a.m. CDT Saturday, carries a Slight Risk from portions of the Ohio Valley into the southern Mid-Atlantic and Carolinas. Its summary reads: "Severe thunderstorms capable of mainly damaging gusts are possible across portions of the Ohio Valley into southern Mid-Atlantic and Carolinas this afternoon and evening." The outlook tracks the same storm complex that was still producing tree damage in Ohio and West Virginia at daybreak, expecting it to continue southeastward across the central Appalachians into the Mid-Atlantic, with the highest chance of damaging gusts across eastern North Carolina. Isolated large hail and severe gusts are also possible over parts of the northern and central Plains today into tonight, per the same outlook.

The Raleigh forecast discussion, issued 8:07 a.m. EDT, leads with the other side of that coin: "Showers and thunderstorms and rain-cooled air this afternoon will provide localized relief from continued heat," with a Heat Advisory in effect for the southern Piedmont, Sandhills, and southern and central coastal plain.

The Weather Prediction Center's excessive rainfall outlook, issued 3:29 a.m. EDT, places a Slight Risk of rain exceeding flash flood guidance over central and eastern Virginia and the eastern Carolinas, the same corridor the storms are expected to work.

Heat in the middle of the country

Ten Extreme Heat Warnings from seven forecast offices cover parts of Missouri, Kansas, Illinois, Iowa, Indiana, and Kentucky this morning, including the St. Louis MO, Kansas City MO, and Topeka KS metros. The St. Louis product, issued 2:29 a.m. CDT, states heat index values up to 110; Paducah's, issued 12:39 a.m. CDT, states 105 to 110 for southern Illinois, southwest Indiana, western Kentucky, and southeast Missouri; Lincoln IL's, issued 6:08 a.m. CDT, states up to 106 for central Illinois. Most of the warnings end at 7 or 8 p.m. CDT this evening, but the heat is not done everywhere: the Kansas City warning for east central Kansas and western Missouri and the Topeka warning both run through Tuesday evening, September 8, and Springfield MO's warning, which cites "multiple consecutive days" of heat index values up to 110, runs through 8 p.m. CDT Sunday. None of the products states a covered population figure.

Southeast Texas rivers

The long tail of Edouard keeps shrinking. Menard Creek near Rye TX, which was in moderate flooding earlier this week, is now in minor flooding per the Houston/Galveston warning extended at 9:38 p.m. CDT Friday, with that warning running until early Saturday afternoon. The Lake Charles office's warning, issued 8:09 p.m. CDT Friday, continues for Village Creek near Kountze TX until Sunday morning, for Pine Island Bayou near Sour Lake TX until early Tuesday, and for the Neches River at the saltwater barrier until Wednesday night. Six counties remain covered: Hardin, Liberty, Polk, Jefferson, Jasper, and Orange.

River warning vitals:

Source: NWS Houston/Galveston and Lake Charles Flood Warnings issued the evening of September 4.

The rest of the tropics

Two more hurricanes are up, both in the Pacific, both far from land, both weakening. Hurricane Karina, per CPHC advisory 36 issued 11 p.m. HST Friday, was about 825 miles east of Hilo HI with 75 mph winds, moving northwest at 8 mph and forecast to become post-tropical by Monday, no watches or warnings. Hurricane Marie, per NHC advisory 17 issued 2 a.m. PDT Saturday, was about 635 miles west of the southern tip of Baja California with 90 mph winds, moving northwest at 8 mph on a gradual weakening trend, no watches or warnings. The Atlantic has no active storms on the NHC board this morning.

Elsewhere

The Weather Prediction Center's Day 1 excessive rainfall outlook, issued 3:29 a.m. EDT and valid through Sunday morning, also carries Marginal Risk areas along the Gulf Coast from Texas to the Florida panhandle, over South Florida, across the Southwest into the southern High Plains and Nebraska, and over a patch of the upper Midwest. In New Mexico, a Flood Watch from the Albuquerque office, issued 9:10 p.m. MDT Friday, covers the South Central Mountains through 6 p.m. MDT this evening.

This is a morning summary, not emergency information. For live warnings see weather.gov and your local officials.

The rock's live forecast for the places in this story

• Honolulu HI
• Lihue HI
• Hilo HI
• Friendsville MD
• Parkersburg WV
• Elizabeth WV
• Hamden OH
• Lexington VA
• Elkton VA
• Crewe VA
• Elizabeth City NC
• North Wilkesboro NC
• Aspermont TX
• Guymon OK
• O'Neill NE
• Dimock SD
• Parkersburg IA
• Monona IA
• Rye TX
• Kountze TX
• Sour Lake TX
• St. Louis MO
• Kansas City MO
• Topeka KS

Key points

• Thursday was a wind day on both ends of the map: 384 preliminary wind reports nationwide, most of them trees and wires down from Pennsylvania and New York through Maryland and Virginia, plus a separate Montana episode that gusted to 83 mph near Great Falls MT.
• Southeast Texas rivers are under Flood Warnings across eight counties this morning, the water still working downstream after Edouard, which the Lake Charles forecast office says has dissipated.
• As of this morning's outlooks: a Slight Risk of severe storms from the southern Great Lakes and Ohio Valley into the Mid-Atlantic, Extreme Heat Warnings across six mid-Mississippi Valley states, and Hurricane Lowell passing well south of Hawaii with no coastal watches in effect.

Yesterday

The loudest weather in the country on Thursday was wind, and it came in two unrelated servings.

The eastern serving started with breakfast. Trees were coming down in Warren PA by 8:05 a.m. EDT on September 3, and for the next twelve hours the reports walked southeast: through western New York around Batavia NY mid-morning, down the spine of central Pennsylvania through midday, then across Maryland and northern Virginia through the early afternoon. Most of it was the same story told a few hundred times, a tree on a road, a tree on wires, a tree on a beltway ramp. Cockeysville MD lost a large uprooted tree at 2:44 p.m. EDT, and Bethesda MD had trees down on River Road at 1:37 p.m. EDT. The evening added a measured exclamation point in the Finger Lakes: a 76 mph gust near Seneca Falls NY at 8:40 p.m. EDT. Pennsylvania, New York, Maryland, and Virginia together accounted for 255 of the day's wind reports.

Montana was the other serving, and it had the day's biggest numbers. Between about 1:30 and 4:30 p.m. MDT, stations across the southwest and central part of the state measured gusts of 70 mph and higher: 83 mph five miles west-southwest of Great Falls MT, 80 mph at Highwood Bench MT and near Warm Springs MT, 77 mph near Choteau MT, and 73 mph in Helena MT itself. Spotters around Butte MT reported large mature trees down, including at a cemetery and a golf course.

Hail was a footnote by comparison. The largest stones were 2 inches, reported at Birch Run MI at 5:38 p.m. EDT and near Capac MI about an hour later. The national log's only tornado-type entry was a single preliminary report near Serenada TX at 4:25 p.m. CDT, which the Austin/San Antonio office logged as pictures and videos of a possible landspout or dust devil.

Largest measured gusts, September 3:

Report counts for the day: 384 wind, 13 hail, 1 tornado-type. By state, wind reports led with Pennsylvania 101, New York 94, Montana 89, Virginia 33, Maryland 27, North Carolina 12, Michigan 11, Ohio 9.

Source: Storm Prediction Center preliminary storm reports for the 24 hours ending 8 a.m. EDT September 4. All counts and gusts are preliminary and subject to revision.

Today, officially

Southeast Texas rivers

The rain from Edouard has stopped falling, but the water is still moving. As of this morning, Flood Warnings cover eight southeast Texas counties: Hardin, Jefferson, Orange, Jasper, Liberty, Polk, Angelina, and Trinity. Menard Creek near Rye TX is in moderate flooding now, per the Houston/Galveston warning continued at 11:26 p.m. CDT Thursday. Village Creek near Kountze TX is forecast to reach moderate flooding, Pine Island Bayou near Sour Lake TX is rising, and the Neches River is forecast for minor flooding both near Diboll TX and down at the saltwater barrier. A separate small-stream Flood Warning for Hardin and northwestern Jefferson counties, issued 4:29 p.m. CDT Thursday, stated plainly that numerous roads remain closed due to flooding.

The Lake Charles forecast discussion, issued 12:13 a.m. CDT Friday, reads: "While Edouard has finally dissipated tonight, a moisture rich atmosphere will remain over the region through the weekend resulting in more showers and storms along with warm and humid conditions." It adds that heavy downpours "could lead to areas of flash flooding especially over already rain sodden ground post-Edouard," and a Marginal Risk of excessive rainfall covers the area both today and Saturday per the Weather Prediction Center outlook issued 2:52 a.m. EDT.

River warning vitals:

Source: NWS Houston/Galveston, Lake Charles, and Shreveport Flood Warnings issued the evening of September 3.

Severe storm risk, Great Lakes to Mid-Atlantic

The Storm Prediction Center's Day 1 outlook, issued 12:37 a.m. CDT Friday, carries a Slight Risk "in a corridor across the southern Great Lakes and middle/upper Ohio Valley into Mid Atlantic," with damaging wind gusts the main concern from organized storm clusters, plus more scattered strong storms east of the Blue Ridge this afternoon and evening. This is the same frontal zone that made Thursday noisy, sagging slowly south.

The Cleveland forecast discussion, issued 3:56 a.m. EDT, reads: "Confidence is increasing for another round of severe storms to move west to east through the area late this morning and afternoon. Damaging wind gusts are the primary concern." That office puts its window roughly between 10 a.m. and 3 p.m., aimed more at northwest and north-central Ohio than the areas hit Thursday.

Heat in the middle of the country

Ten Extreme Heat Warnings from six forecast offices cover parts of Missouri, Kansas, Iowa, Illinois, Indiana, and Kentucky as of early this morning, taking in the St. Louis MO, Kansas City MO, and Topeka KS metros. The St. Louis product, issued 3:26 a.m. CDT, states heat index values up to 107; the Kansas City product, issued 4:18 a.m. CDT, states up to 105. Several of the warnings run through 8 p.m. Saturday, and the Kansas City and Topeka warnings for the western zones run through 8 p.m. Tuesday, September 8. None of the products states a covered population figure.

The tropics

Three hurricanes are active, all in the Pacific, and none carries a coastal watch or warning. The one worth a homeowner's glance is Hurricane Lowell. Per Central Pacific Hurricane Center advisory 32, issued 11 p.m. HST Thursday, Lowell was a category 3 with maximum sustained winds of 125 mph and a 947 mb central pressure, about 555 miles south-southwest of Honolulu HI and 595 miles south of Lihue HI, moving west at 9 mph with a turn toward the northwest and north expected this weekend. The advisory's stated land hazard is surf: swells likely to cause life-threatening surf and rip current conditions across many of the Hawaiian islands during the next several days. The advisory headline asks interests in the Hawaiian Islands to continue monitoring; the next complete advisory was scheduled for 5 a.m. HST.

Hurricanes Karina (advisory 32) and Marie (advisory 13), both per NHC advisories issued 5 a.m. EDT Friday, are over open eastern Pacific water, far from land, with no watches or warnings. The Atlantic has no active storms on the NHC board this morning.

Elsewhere

The Weather Prediction Center's excessive rainfall outlook, issued 2:52 a.m. EDT and valid through Saturday morning, places a Slight Risk of rainfall exceeding flash flood guidance over parts of southeastern Arizona and southwestern New Mexico, with Marginal Risk areas including southeast Texas, South Florida, and a broad stripe from the Great Lakes to the Carolinas. Flash Flood Watches from the Boise and Pocatello offices cover several Idaho mountain zones and Baker County OR into this evening.

This is a morning summary, not emergency information. For live warnings see weather.gov and your local officials.

The rock's live forecast for the places in this story

• Warren PA
• Batavia NY
• Seneca Falls NY
• Bethesda MD
• Cockeysville MD
• Great Falls MT
• Helena MT
• Butte MT
• Choteau MT
• Birch Run MI
• Capac MI
• Serenada TX
• Rye TX
• Kountze TX
• Sour Lake TX
• Diboll TX
• St. Louis MO
• Kansas City MO
• Topeka KS
• Honolulu HI
• Lihue HI

Key points

• Wednesday put 334 preliminary wind reports on the board across two separate theaters: New York led all states with 94 and Montana ran second with 85, including a measured 83 mph gust at the Great Falls airport and trees dropped onto houses across the Finger Lakes.
• The Weather Prediction Center issued its last advisory on Edouard's remnants at 4 a.m. CDT Thursday, near Dallas; gauges northwest of Beaumont have already measured over 17 inches of rain, 2 to 4 more inches are possible over northeast Texas today, and flood warnings covered a dozen east Texas counties Thursday morning.
• Three Pacific hurricanes, Lowell at category 4 south of Hawaii, Karina at category 3, and Marie newly a hurricane, carry no coastal watches or warnings; Lowell's swell is expected to bring life-threatening surf to the Hawaiian Islands over the next several days.

The rock's morning read on what the country's weather did yesterday, and what is officially expected today. Sources are the wire products themselves, cited as they read.

Yesterday: the wind ran wide

Wednesday worked both ends of the country. The storms in the East started early: county dispatch in Warren, Pennsylvania reported a tree down over South State Street at 8:05 a.m. EDT, and by 8:25 a.m. tree limbs had knocked out power to several hundred customers around Batavia, New York. That was only the opening act. Storms kept re-firing across New York and Pennsylvania through the afternoon and evening, and the day ended with New York holding 94 wind reports, the most of any state, and Pennsylvania 84. The Finger Lakes took the hardest evening hit. The New York State Mesonet station at Waterloo measured a 76 mph gust at 8:40 p.m. EDT, and the report log for Waterloo and Seneca Falls describes numerous trees and wires down, including trees onto houses. Trees landed on houses in Olcott, Amherst, and Webster too, and in Ischua down in Cattaraugus County. The southern end of the line reached Virginia by late afternoon, with multiple trees and power lines blocking roads in Orange County and a tree onto a house near New Canton in Buckingham County, and it finished in North Carolina, where Franklin County logged downed power lines around Louisburg into the evening.

Montana had its own windstorm entirely. Eighty-five reports came out of the state, and the numbers were the story: the ASOS at Great Falls International Airport measured 83 mph at 3:53 p.m. MDT, stations near Warm Springs and on the Highwood Bench both hit 80 mph, and the Helena airport gusted to 71 mph as the wind worked east across the state through the afternoon. A spotter in Chester reported several trees down and a power outage that lasted until around 6:15 p.m. MDT.

The hail was a footnote by comparison, twelve reports, the largest 2 inches at Birch Run and near Capac in Michigan's Thumb. The country produced exactly one tornado report: the log lists a landspout near Serenada in Williamson County, Texas at 4:25 p.m. CDT, and hedges its own entry with pictures and videos "of a possible landspout or dust devil." The rock respects a report that admits what it does not know.

The numbers

Report count for the 12Z September 2 to 12Z September 3 period: 334 wind, 12 hail, 1 tornado (the Williamson County, Texas landspout report). Wind reports by state: New York 94, Montana 85, Pennsylvania 84, Virginia 27, Maryland 20, North Carolina 12, Michigan 6, Ohio 3, one each Nebraska, Iowa, South Dakota. Hail reports: Michigan 5, Pennsylvania 3, New York 2, one each Virginia and Montana.

Top measured gusts:

Largest hail:

Source: Storm Prediction Center storm reports for the 12Z September 2 to 12Z September 3 period. All reports are preliminary; SPC labels them so and this brief does too. Times are converted from UTC. The Timberville hail time was estimated via radar per the report remarks.

Yesterday: Edouard's rain kept falling

While the wind made noise elsewhere, Tropical Depression Edouard spent Wednesday doing exactly what the advisories said it would: raining on east Texas. The Weather Prediction Center's Storm Summary Number 3, issued 11 p.m. EDT Wednesday, put the depression over southeastern Texas with heavy rain and gusty winds still on the radar, and its preliminary storm total list tells the story plainly. The gauge at Little Pine Island Bayou at SH 787 had measured 17.75 inches since Monday morning. A RAWS station at Southern Rough read 16.53 inches, a citizen station at Warren 15.69, and Kountze 13.39. Woodville and Livingston sat near 8 to 9 inches, and Beaumont's southwest side near 7. The summary expected another 2 to 4 inches overnight, locally as much as 8, and flash flood warnings were in effect northeast of Houston and northwest of Beaumont as it went to press.

Storm totals, by the gauge

Source: WPC Storm Summary Number 3 for Edouard (ACUS45 KWBC), issued 11 p.m. EDT September 2. Totals are preliminary and run from 8 a.m. EDT August 31 through 10 p.m. EDT September 2.

Today, officially

Edouard signs off; the water has not

As of Advisory Number 12, issued 4 a.m. CDT Thursday by the Weather Prediction Center, the remnants of Edouard sat about 40 miles southeast of Dallas with 25 mph winds, drifting west-northwest at 5 mph toward dissipation within 24 hours. It is the last public advisory on the system that came ashore at Johnson Bayou on Monday. The rainfall language stays serious to the end: "Additional rainfall totals of 2 to 4 inches are possible across northeast Texas Thursday. This will bring total rainfall amounts along the path of Edouard to 5 to 10 inches, with maximum totals up to 22 inches." The advisory adds that additional flash flooding is possible through Thursday and that "isolated moderate to major river flooding is expected."

The morning's warnings agree. As of Thursday morning, flood warnings from the Houston/Galveston, Shreveport, and Lake Charles offices covered twelve east Texas counties: Liberty, Polk, San Jacinto, Trinity, Angelina, Anderson, Cherokee, Houston, Hardin, Jasper, Jefferson, and Orange. Shreveport's river warnings run into Friday morning. Flood watches from Shreveport, Houston/Galveston, and Fort Worth hold through Thursday afternoon across deep east Texas. The WPC Day 1 excessive rainfall outlook, issued 4:05 a.m. EDT Thursday, keeps a Slight Risk over east Texas, with a second Slight Risk over southeast Arizona.

The Shreveport Area Forecast Discussion, issued 1 a.m. CDT Thursday, notes that in its area "the ground has been able to soak up the majority of the rainfall today, with minimal flooding impacts actually observed," and closes the chapter with a sentence the rock could have written: "Edouard exits the stage to the left, the ridge rebuilds, the thermometer remembers what summer is supposed to feel like, and the diurnal thunderstorm machine gradually cranks back up."

Official preparedness guidance lives at Ready.gov (https://www.ready.gov/), and the state emergency management agency is the Texas Division of Emergency Management (https://tdem.texas.gov/).

Final advisory vitals, per Advisory 12 (4 a.m. CDT September 3):

Behind Wednesday's storms: flood warnings from Lake Ontario to Delaware

The water bill for Wednesday's eastern storms came due overnight. As of Thursday morning, the State College office carried flood warnings across nine central Pennsylvania counties, Centre, Clinton, Clearfield, Huntingdon, Juniata, Mifflin, Perry, McKean, and Warren, plus a Flash Flood Warning issued 4:11 a.m. EDT for Dauphin, Lancaster, and Lebanon counties, and a Flood Watch across the central mountains through midnight tonight. Mount Holly issued a flood warning at 7:15 a.m. EDT covering the Philadelphia suburbs in Bucks, Chester, Delaware, and Montgomery counties, New Castle County in Delaware, and Burlington, Camden, Gloucester, and Salem counties in New Jersey. To the north, Buffalo held flood warnings for Monroe and Orleans counties in New York, and Cleveland for Erie County, Pennsylvania. Most of the morning warnings expire before midday; the Monroe County, New York warning runs into Thursday evening.

Severe weather: Slight Risks, Great Lakes to Mid-Atlantic and northern Plains

The Storm Prediction Center's Day 1 outlook, issued 12:53 a.m. CDT Thursday and valid through 7 a.m. CDT Friday, reads: "Scattered strong thunderstorm development is likely today through tonight, perhaps including a few organizing clusters, posing a risk for severe wind and hail across parts of the southern Great Lakes into Mid Atlantic and portions of the northern Great Plains into Upper Midwest." In the East, the outlook expects a stalled outflow boundary and front to focus renewed storms from southeastern Wisconsin across lower Michigan, northern Indiana, and Ohio toward the northern Mid-Atlantic, with strong downbursts the main concern and a note that wind probabilities could still be raised later. On the Plains, northern and eastern North Dakota into northwestern Minnesota could see a few supercells this afternoon and evening, with large hail the leading threat.

The tropics: three hurricanes, zero watches

Per the advisories issued 9 UTC Thursday, none of the three Pacific hurricanes carries coastal watches or warnings:

Lowell's advisory says swells "are spreading northward and will affect portions of the Hawaiian Islands during the next several days," with life-threatening surf and rip current conditions likely, and expects Lowell to remain a major hurricane for the next several days. Karina has eased from Tuesday's 145 mph to category 3 and is forecast to weaken gradually while staying a hurricane a couple more days. Marie, a tropical storm on Wednesday, is now a hurricane and still strengthening; its swell reaches southwest Mexico and Baja California over the next few days and likely spreads to southern California over the weekend. The next advisories on all three come at 5 a.m. HST and 8 a.m. MST. Three hurricanes, not one watch among them; the ocean continues its loud work in empty rooms.

Otherwise

Extreme Heat Warnings were in effect Thursday morning from five forecast offices: Chicago, Quad Cities, Lincoln, St. Louis, and Paducah. Chicago's warning, issued 1:08 a.m. CDT for Cook County, expects heat index values of 100 to 105 and notes this is "the third day in a row with a forecast or observed maximum heat index over 100 degrees," with a cold front off Lake Michigan expected to end it this afternoon and evening. Another 54 heat advisories cover the mid Mississippi and Ohio valleys around that core; none of the products states a population figure, and the pattern breaks tonight. Separately, Bismarck issued a Flash Flood Warning at 6:18 a.m. CDT for parts of McHenry and Ward counties in North Dakota. No winter products of consequence.

---

This is a morning summary, not emergency information. For live warnings see https://www.weather.gov/ and your local officials.

The rock's live forecast for the places in this story

• Seneca Falls NY
• Waterloo NY
• Batavia NY
• Olcott NY
• Great Falls MT
• Helena MT
• Choteau MT
• Fort Benton MT
• Chester MT
• Birch Run MI
• Meadville PA
• Timberville VA
• Louisburg NC
• Kountze TX
• Woodville TX
• Livingston TX
• Beaumont TX
• Dallas TX
• Chicago IL
• Hilo HI

Key points

• Tropical Storm Edouard came ashore near Johnson Bayou, Louisiana at 2:20 p.m. CDT yesterday with 60 mph winds, short of hurricane strength; it is now a depression over east Texas, and today's story is the rain, with 4 to 8 inches forecast along its path and up to 12 possible.
• Yesterday was a loud severe weather day on two fronts: 137 preliminary wind reports and 35 hail reports nationwide, including a measured 98 mph gust in northeast Nebraska and a long evening of downed trees from Pennsylvania through New Jersey and Delaware.
• Two category 4 hurricanes, Karina and Lowell, are spinning in the Pacific with 145 mph winds each; neither carries coastal watches or warnings, though Lowell's swell is expected to reach Hawaii starting Wednesday.

The rock's morning read on what the country's weather did yesterday, and what is officially expected today. Sources are the wire products themselves, cited as they read.

Yesterday: Edouard came ashore

The wait ended Tuesday afternoon. At 2:20 p.m. CDT on September 1, radar out of Lake Charles and Houston put the center of Tropical Storm Edouard over the marsh at Johnson Bayou, Louisiana, just east of the Texas line. The National Hurricane Center's landfall update estimated maximum sustained winds at 60 mph and a central pressure of 996 mb. The near-hurricane the previous day's advisories had left room for never showed up; Edouard spent its morning holding at 50 mph, added a little strength in the final hours, and crossed the coast as a solid but ordinary tropical storm.

The wind did its loudest work right at the corner of the two states. The National Ocean Service station at Texas Point, Texas caught a sustained wind of 57 mph and a gust to 71 mph just before landfall, and Port Arthur gusted to 49 mph an hour later as the center passed close to the city. By 10 p.m. EDT, the Weather Prediction Center's first storm summary described a very compact storm crawling northwest at 7 mph, with its heaviest bands producing rain at 2 to 3 inches per hour. Overnight the center crossed into the Piney Woods of east Texas, and the Houston office estimated 6 to 8 inches had already fallen close to the core by 2 a.m. CDT.

Landfall, by the numbers

Source: NHC Tropical Cyclone Updates for Edouard issued 2 p.m., 2:25 p.m., and 3 p.m. CDT September 1, and WPC Storm Summary Number 1, issued 11 p.m. EDT September 1. The gust list is that summary's preliminary selection.

Yesterday: a 98 mph gust in Nebraska and a treefall evening in the East

While the Gulf Coast watched Edouard, the two Slight Risk areas from Monday's outlooks both produced. The louder number came from the Plains. A Nebraska Mesonet station near Fordyce, in Cedar County, measured a 98 mph wind gust at 8:32 p.m. CDT. Minutes earlier a tractor trailer was tipped onto its side near the Highway 12 and US 81 junction, and 12 inch tree limbs came down across the town of Wynot. The same storms threw large hail across the Nebraska and South Dakota border country: stones to 2.75 inches at Pickstown, South Dakota at 5:18 p.m. CDT, and baseball size hail at Niobrara, Nebraska at 7:44 p.m. CDT that broke a vehicle windshield. The night ended in Minnesota, where an AWOS station at the Mayo Helipad in Rochester gusted to 68 mph at 1:35 a.m. CDT with large trees down and power outages.

The East's version was quieter per report and much wider. From about 6:12 p.m. EDT, when county dispatch in Meadville, Pennsylvania began reporting multiple trees and power lines down, storms worked southeast across Pennsylvania through the evening: Berks, Chester, Carbon, Lehigh, and Bradford counties fill page after page of the report log with trees on wires and closed roads. After dark the line reached Delaware and South Jersey. New Castle County, Delaware logged multiple roads closed by downed trees around Wilmington and Newark, and Gloucester and Salem counties in New Jersey reported numerous trees and power lines down, with Route 49 fully closed at Salem. Pennsylvania alone accounted for 58 of the day's wind reports.

The numbers

Report count for the 12Z September 1 to 12Z September 2 period: 137 wind, 35 hail, 0 tornado. Wind reports by state: Pennsylvania 58, New Jersey 16, South Dakota 14, Nebraska 11, Delaware 11, Iowa 8, Minnesota 7, Wisconsin 6, New York 3, one each Texas, Idaho, California. Hail reports: Nebraska 21, South Dakota 9, Minnesota 3, one each Iowa and New Jersey.

Top measured gusts:

Largest hail:

Source: Storm Prediction Center storm reports for the 12Z September 1 to 12Z September 2 period. All reports are preliminary; SPC labels them so and this brief does too. Several gusts came from personal weather stations per the report remarks; times are converted from UTC.

Today, officially

Edouard inland: the rain is the story now

As of Advisory Number 8, issued 4 a.m. CDT Wednesday by the Weather Prediction Center, Tropical Depression Edouard sat about 30 miles south-southwest of Lufkin, Texas, drifting north-northwest at 5 mph with 35 mph winds. The advisory expects Edouard to dissipate Wednesday night. Its rainfall language is direct: "Total rainfall along Edouard's path is expected to range from 4 to 8 inches, with maximum totals up to 12 inches for parts of the Upper Texas Coast inland through east-central Texas. This rainfall is likely to produce flash flooding, especially in low-lying and urban areas. Significant flash flooding is possible." A brief tornado or two remained possible through early Wednesday morning across parts of southwest Louisiana and southeast Texas.

The warnings on the ground Wednesday morning matched that language. Between 4:46 and 6:04 a.m. CDT, the Lake Charles and Houston offices issued Flash Flood Warnings covering Polk, San Jacinto, Liberty, Montgomery, Hardin, Tyler, Chambers, and Jefferson counties in Texas. Flood Watches from four forecast offices run through Wednesday afternoon and evening across east Texas, from the Houston metro north and east through the Piney Woods into the Fort Worth and Shreveport forecast areas.

The Houston Area Forecast Discussion, issued 1:59 a.m. CDT Wednesday, reads it this way: "The primary threat through tonight is heavy rainfall," with the highest risk "generally north of I-10 and along and east of I-45," and a forecast "swath of 6-8 inch rainfall totals in a SE to NW orientation from Northern Liberty to Houston County through Thursday." That discussion also notes WPC had upgraded portions of the Piney Woods to a Moderate Risk for excessive rainfall; the WPC Day 1 excessive rainfall outlook issued later, at 4:04 a.m. EDT and valid from 8 a.m. EDT Wednesday, carries a Slight Risk over east Texas. The two products read differently and are reported here as they read.

Official preparedness guidance lives at Ready.gov (https://www.ready.gov/), and the state emergency management agencies are the Texas Division of Emergency Management (https://tdem.texas.gov/) and Louisiana GOHSEP (https://gohsep.la.gov/).

Advisory vitals, per Advisory 8 (4 a.m. CDT September 2):

Severe weather: Slight Risks east and west

The Storm Prediction Center's Day 1 outlook, issued 12:57 a.m. CDT Wednesday and valid through 7 a.m. CDT Thursday, carries two Slight Risk areas. As the summary reads: "Severe thunderstorms are possible across portions of the eastern Great Lakes to the Mid-Atlantic today and tonight. Damaging wind gusts are the main threat, though some large hail and a few tornadoes may also occur. Scattered severe gusts and more sporadic occurrences of large hail appear possible from the northern Rockies into northern High Plains Wednesday afternoon into night." In the East, the outlook describes a complex day of repeated storm rounds, with a possible greater tornado risk in the evening across southern New York and central Pennsylvania, "contingent upon air mass recovery" behind the morning storms. In Montana, the outlook expects a fast-moving line by late afternoon with scattered severe gusts likely and peak intensity of 65 to 80 mph possible.

The tropics: two category 4s, both far from land

Per the advisories issued 9 UTC Wednesday, none of the three Pacific storms carries coastal watches or warnings:

Lowell's advisory headline reads, "LOWELL FORECAST TO BE A POWERFUL HURRICANE FOR THE NEXT SEVERAL DAYS," and its hazards section says swells "are likely to affect portions of the Hawaiian Islands beginning on Wednesday" with life-threatening surf and rip current conditions likely. Marie is forecast to become a hurricane later today, with its swell reaching southwest Mexico and Baja California in the coming days and likely spreading to southern California over the weekend. Two 145 mph storms on the same map and not one watch between them: the ocean is doing loud things in empty rooms, and the rock approves.

Otherwise

Extreme Heat Warnings were in effect Wednesday morning from the Quad Cities and Paducah forecast offices, and heat advisories covered a broad stretch of the mid Mississippi and Ohio valleys, in ordinary early-September numbers and below this brief's bar for news. No winter products of consequence.

---

This is a morning summary, not emergency information. For live warnings see https://www.weather.gov/ and your local officials.

The rock's live forecast for the places in this story

• Johnson Bayou LA
• Port Arthur TX
• Beaumont TX
• Cameron LA
• Lufkin TX
• Houston TX
• Fordyce NE
• Wynot NE
• Niobrara NE
• Pickstown SD
• Rochester MN
• Meadville PA
• Wilmington DE
• Salem NJ
• Hilo HI

Key points

• Tropical Storm Edouard is forecast to strengthen, possibly to near hurricane strength, before reaching the northwest Gulf Coast later today; a Storm Surge Warning, a Hurricane Watch, and Tropical Storm Warnings cover the Texas and Louisiana coast per National Hurricane Center Advisory 4.
• Yesterday was one of the quietest severe weather days of the summer: 13 preliminary wind reports and one hail report nationwide, no tornadoes.
• The Storm Prediction Center carries a Slight Risk today from the central and northern Plains across the Midwest into Pennsylvania, New York, and New Jersey.

The rock's morning read on what the country's weather did yesterday, and what is officially expected today. Sources are the wire products themselves, cited as they read.

Yesterday: the depression got a name

The weather story of Monday, August 31 happened over water. At 7 p.m. CDT, the National Hurricane Center's Intermediate Advisory 2A announced that Tropical Depression Five had strengthened into Tropical Storm Edouard, about 140 miles southeast of Cameron, Louisiana. Three hours later, Advisory 3 at 10 p.m. CDT raised the stakes on the coast: a Storm Surge Warning from High Island, Texas to the Vermilion/Cameron Parish line, and a Hurricane Watch for a portion of the northwest Gulf Coast. The evening on land was the quiet before it, spent watching radar out of Lake Charles.

The rest of the country barely made a sound. Thirteen wind reports and one hail report came in all day, and no tornadoes anywhere. Most of the wind was monsoon outflow working the Four Corners and the High Plains. The one report with real damage behind it came from La Paz County, Arizona, where photos showed power poles down at Avenue 42E about six miles southeast of Bouse around 3 p.m. MST. The day's top measured gust was 77 mph at a personal weather station southeast of Lamar, Colorado at 6:30 p.m. MDT. The country's only hail fell at Kershaw-Ryan State Park near Caliente, Nevada: one-inch stones at 11:10 a.m. PDT.

The numbers

Report count for the day: 13 wind, 1 hail, 0 tornado. Reports ran from Juab County, Utah and La Paz County, Arizona through Alamosa, Prowers, Bent, Kiowa, and Cheyenne counties in Colorado, Cheyenne County in Kansas, Rio Arriba and Bernalillo counties in New Mexico, and Lincoln County, Nevada.

Top measured gusts, August 31:

Source: Storm Prediction Center storm reports for the 12Z August 31 to 12Z September 1 period. All reports are preliminary; SPC labels them so and this brief does too. The Lamar gusts came from a personal weather station, per the report remarks; times are converted from UTC.

Today, officially

Edouard, landfall day

As of National Hurricane Center Advisory Number 4, issued 4 a.m. CDT Tuesday, September 1, the center of Tropical Storm Edouard sat about 65 miles south-southeast of Cameron, Louisiana and 90 miles southeast of Port Arthur, Texas, moving west-northwest at 8 mph with top sustained winds of 40 mph. The advisory's headline reads, "Edouard poised to significantly strengthen before reaching the northwest Gulf Coast later today." In its words: "Significant strengthening is forecast today and Edouard could approach hurricane strength before it reaches the northwest Gulf coast later today," and "the center of Edouard is forecast to reach the northwestern Gulf Coast within the warning area later today and move inland over southeast Texas tonight."

The watch and warning footprint, per that advisory:

- A Storm Surge Warning from High Island, Texas to the Vermilion/Cameron Parish line, Louisiana.

- A Hurricane Watch from High Island, Texas to Cameron, Louisiana.

- A Tropical Storm Warning from Port Bolivar, Texas to the Vermilion/Iberia Parish line, Louisiana.

On land, per NWS zone alerts active early Tuesday, the Tropical Storm Warning covered the Bolivar Peninsula, Chambers, Southern Liberty, Upper and Lower Jefferson, Orange, Hardin, Southern Jasper, and Southern Newton in Texas, and West Cameron, East Cameron, and Lower Vermilion in Louisiana. The Storm Surge Warning zones were Lower Jefferson County, Texas and West and East Cameron parishes, Louisiana; the Hurricane Watch zones were Lower Jefferson County and West Cameron Parish. A Flood Watch runs through 7 a.m. CDT Wednesday for southeast Texas counties including Harris, Galveston, Fort Bend, Brazoria, Montgomery, Liberty, Chambers, Walker, San Jacinto, Polk, Tyler, Hardin, Jasper, Newton, Jefferson, and Orange.

The Lake Charles Area Forecast Discussion, issued 1:05 a.m. CDT Tuesday, reads the landfall this way: the storm is "tracking toward Southeast Texas for a landfall near Sabine, TX by this afternoon," and "a hurricane watch has been added to Jefferson county and western Cameron Parish where the greatest wind threat will be." On the rain: "Heavy rainfall with the potential for flash flooding of urban areas will be possible around where the center of the low moves."

If you live in the footprint, official preparedness guidance lives at Ready.gov (https://www.ready.gov/), and the state emergency management agencies are the Texas Division of Emergency Management (https://tdem.texas.gov/) and Louisiana GOHSEP (https://gohsep.la.gov/).

Advisory vitals, per NHC Advisory 4 (4 a.m. CDT September 1):

The companion forecast discussion, same issue time, puts the expected landfall intensity at 55 knots and calls the intensity forecast "problematic," noting 31 C sea-surface temperatures and low wind shear in the storm's path. Storm page: https://www.nhc.noaa.gov/graphics_at5.shtml

Severe weather: a Slight Risk from the Plains to New Jersey

The Storm Prediction Center's Day 1 outlook, issued 1:03 a.m. CDT Tuesday and valid through 7 a.m. CDT Wednesday, carries a Slight Risk in two areas. As the summary reads: "Scattered strong to severe storms are possible over the central Plains and Midwest, as well as parts of New York, Pennsylvania and New Jersey." In the East, the outlook expects a mix of supercells and line segments across southern New York, Pennsylvania, and New Jersey through the afternoon, with damaging gusts and isolated hail the most likely hazards and, near the southern Hudson Valley, enough low-level shear that "a couple of tornadoes" are possible with the stronger storms. On the Plains, supercells along a stalled front over Nebraska and South Dakota could produce hail over two inches, damaging gusts, and "a tornado or two," with a storm cluster possibly running the front into eastern South Dakota and southern Minnesota through the evening.

Excessive rainfall

The Weather Prediction Center's Day 1 excessive rainfall outlook, issued 4:16 a.m. EDT Tuesday and valid through 8 a.m. EDT Wednesday, puts a Slight Risk of rainfall exceeding flash flood guidance over southeast Texas, the same ground Edouard's center crosses. Marginal Risk areas cover parts of the Northeast and mid-Atlantic (the same air the severe risk works), the Florida peninsula, a broader piece of Texas and Louisiana, and the monsoon country of the Southwest.

The rest of the tropics

Three more storms, all in the Pacific, none with coastal watches or warnings as of the advisories issued 9 UTC Tuesday:

Marie is new, named on its first advisory at 2 a.m. MST Tuesday, well offshore of southwest Mexico. The Lowell advisory headline reads, "LOWELL FORECAST TO BECOME A HURRICANE OVERNIGHT AND INTO TUESDAY." Hilo stays a name on that map, so the rock keeps reading the advisories.

Otherwise

Heat advisories stretched across the Midwest on Tuesday morning, from Kansas and Missouri through Iowa, Illinois, Indiana, and Ohio, in ordinary early-September numbers and below this brief's bar for news. No winter products of consequence, no widespread flood warnings.

---

This is a morning summary, not emergency information. For live warnings see https://www.weather.gov/ and your local officials.

The rock's live forecast for the places in this story

• Port Arthur TX
• Cameron LA
• High Island TX
• Morgan City LA
• Lamar CO
• Bouse AZ
• Caliente NV
• Hilo HI

Key points

• A 112-report thunderstorm wind day swept the northern Plains Sunday, topped by a preliminary 100 mph gust at Buffalo, South Dakota.
• Tropical Depression Five carries a Tropical Storm Warning for the Texas and Louisiana coast, per the National Hurricane Center advisory.
• Monsoon moisture keeps flash flood concerns alive across southern Utah and Arizona.

The rock's morning read on what the country's weather did yesterday, and what is officially expected today. Sources are the wire products themselves, cited as they read.

Yesterday: the wind crossed the shortgrass

Sunday afternoon, August 30, a long line of thunderstorm wind ran from southeast Montana across the far corner of Wyoming into northwest South Dakota and southwest North Dakota. It started quietly, with gusts in the 60s along I-80 in Wyoming and at Montana mesonet stations through the early afternoon. Then it found Harding County, South Dakota. At 3:31 p.m. MDT a station one mile north of Buffalo measured a 100 mph gust. That number is the story of the day.

Buffalo took it hard by the reports that came in afterward: significant tree damage, shingles blown off house roofs, some building damage from falling trees, and a few trees uprooted. The wind kept working northeast through the evening. In Sturgis, trees and large limbs came down, including the top half of a large evergreen snapped off. Across the state line in Hettinger, North Dakota, mature pine trees were uprooted in town and law enforcement reported a downed powerline near the high school football field. East of there, near Haynes, a ham radio operator relayed a photo of a house with its metal roof partially peeled back.

For all that wind, the day produced no tornado reports, and exactly one hail report in the whole country: quarter-sized stones at Big Water, Utah, at 4:33 p.m. MDT, in the same monsoon air that matters again today.

The numbers

Top measured gusts, August 30 (all times MDT):

Report count for the day: 112 wind, 1 hail, 0 tornado. Reports ran from Carbon County, Wyoming and Garfield County, Montana through Harding, Butte, Meade, Perkins, Lawrence, and Pennington counties in South Dakota into Adams, Bowman, and Mountrail counties in North Dakota.

Source: Storm Prediction Center storm reports for the 12Z August 30 to 12Z August 31 period. All reports are preliminary; SPC labels them so and this brief does too. The Hettinger gust was measured at 10 meters, with 56 mph observed at the surface, per the report remark.

Today, officially

Tropical Depression Five, aimed at the upper Texas coast

A newly formed depression sat over the northwest Gulf on Monday, and the products stacked up along the coast from Texas to Louisiana through the day. As of National Hurricane Center Advisory Number 2, issued 4 p.m. CDT Monday, August 31, the center sat about 105 miles south of Morgan City, Louisiana, drifting west-northwest at 6 mph with top sustained winds of 35 mph. The advisory expects it to become a tropical storm Monday evening. In the advisory's words, "the center of the system is predicted to reach the northwestern Gulf Coast within the warning area on Tuesday and move inland over southeast Texas on Tuesday night."

The watch and warning footprint, per that advisory:

- A Tropical Storm Warning from Port Bolivar, Texas to the Vermilion/Iberia Parish line, Louisiana. This advisory extended the warning eastward to that parish line.

- A new Storm Surge Watch from High Island, Texas to the Vermilion/Cameron Parish line, Louisiana.

On land, per NWS zone alerts active Monday evening, the warning covered the Bolivar Peninsula and Chambers County in Texas and Lower Jefferson, West Cameron, and East Cameron parishes in Louisiana. The rain is the larger concern in the local offices' reading. Flood Watches from NWS Houston/Galveston (through 4 a.m. CDT Tuesday) and NWS Lake Charles (through 10:15 a.m. CDT Tuesday) covered counties including Harris, Galveston, Chambers, Montgomery, Liberty, Polk, San Jacinto, Tyler, Hardin, Jefferson, and Orange.

The Lake Charles Area Forecast Discussion, issued 2:13 p.m. CDT Monday, put it plainly: "The main story over the next few days will be TD5 moving across the northwest Gulf and toward the southwest Louisiana/southeast Texas coast today and inland on Tuesday." And on the stakes: "Heavy rainfall with the potential for flash flooding of urban areas will be possible around where the center of the low moves." The same discussion notes, "Wind and surge impacts from the disturbance are expected to be minor at this time."

If you live in the footprint, official preparedness guidance lives at Ready.gov (https://www.ready.gov/), and the state emergency management agencies are the Texas Division of Emergency Management (https://tdem.texas.gov/) and Louisiana GOHSEP (https://gohsep.la.gov/).

Advisory vitals, per NHC Advisory 2 (4 p.m. CDT August 31):

Storm page: https://www.nhc.noaa.gov/graphics_at5.shtml

Severe weather: a Marginal day

The Storm Prediction Center's Day 1 outlook, updated 2:28 p.m. CDT Monday and valid through 7 a.m. CDT Tuesday, carries nothing above a Marginal Risk. As the outlook summary reads: "Isolated strong to severe thunderstorms may occur this afternoon into tonight across parts of the Upper Midwest/Great Lakes into western New York, the central Plains, and lower Colorado River Valley into the Great Basin. Severe hail and strong/damaging winds should be the main threats."

The Southwest monsoon, still busy

The Weather Prediction Center's Day 1 excessive rainfall outlook, issued 11:51 a.m. EDT Monday and valid through 8 a.m. EDT Tuesday, includes a Moderate Risk of rainfall exceeding flash flood guidance whose boundary points sit in southern Utah and northern Arizona, with a broader Slight Risk around it. The local offices' own products name the ground: Flood Watches were in effect Monday from NWS Salt Lake City (zones including Southwest Utah, Lower Washington County, and Zion National Park, through 9 p.m. MDT), NWS Flagstaff (Kaibab Plateau, Grand Canyon Country, Marble and Glen Canyons, through midnight MST), NWS Phoenix, NWS Las Vegas, and NWS Grand Junction. Yesterday's lone hail report at Big Water, Utah fell in this same regime.

The rest of the tropics

Two more systems, both far from land, both without coastal watches or warnings as of the 11 a.m. HST Monday advisories:

The Lowell advisory headline reads, "LOWELL FORECAST TO INTENSIFY RAPIDLY OVER THE NEXT DAY OR TWO." Hilo is a name on that map, so the rock will keep reading the advisories.

Otherwise

Quiet, in the way late August is quiet. Heat advisories dotted the map Monday in ordinary summer numbers, below this brief's bar for news. No winter products of consequence, no widespread flood warnings outside the areas above.

---

This is a morning summary, not emergency information. For live warnings see https://www.weather.gov/ and your local officials.

Grounded in National Weather Service definitions; suitable for classrooms and other curious humans.

Sunlight looks white, but it is every color traveling together. The air itself takes those colors apart: its molecules knock the short blue light waves sideways far more than the long red ones, so scattered blue comes at your eyes from every direction overhead. That is the whole sky. Near the horizon the light has crossed so much air that the blue gets scattered away and remixed, which is why the edges look pale, and at sunset the path is longest of all, which is why the leftovers run orange and red.

First, take the light apart

Start with a question that sounds too easy: what color is sunlight? Not blue. Not yellow, whatever the crayon box says. Sunlight is every color at once, and you have already seen the proof. When rain splits a sunbeam you get a rainbow: red, orange, yellow, green, blue, violet, all of which were riding inside that white light the whole time. White is simply what the colors look like when they travel together.

So the real question is sneakier. If every color arrives from the sun, who is sorting them, and why does blue get the whole ceiling?

The air picks favorites

The air is not empty. It is a crowd of molecules, mostly nitrogen and oxygen, each one absurdly small. Light travels in waves, and the colors differ by wave size: blue waves are short and choppy, red waves are long and lazy. When sunlight runs this crowd of tiny molecules, the short blue waves get knocked sideways, again and again, while the long red waves mostly plow straight through. Scientists call the knocking scattering, and the fussy version of the rule is named Rayleigh scattering, after Lord Rayleigh, who worked out the mathematics of it in the 1870s.

Here is the part worth sitting with. The scattered blue does not vanish. It bounces from molecule to molecule across the whole dome, and some of it ends its trip in your eye. Look anywhere in the sky except at the sun and you are seeing sunlight that took a detour. The blue overhead is not a painted ceiling. It is a detour, arriving from everywhere at once.

Why the edges go pale

Now look at the horizon, out where the sky meets the rooftops. Paler, right? Light arriving from low in the sky has skimmed sideways through far more air than light dropping from straight overhead. Over that long trip, the blue gets scattered out of the line, scattered back in, and scattered again, until the colors remix toward a milky white. The sky is bluest straight up because that is the shortest trip through the crowd.

The sunset payoff

At sunset the trip is the longest it ever gets. Sunlight comes in nearly flat, crossing the thickest possible slice of air, and by the end of that road almost all the blue has been knocked out and handed to somebody else's afternoon. What survives the trip is the long-wave end of the light: orange and red. A sunset is not the sky changing its mind. It is the same rule as noon, run to the end.

So why are clouds white?

Because a cloud is not made of molecules doing the knocking. It is made of water droplets, each one enormously bigger than an air molecule, and droplets that size scatter all the colors about equally. All colors together is white, so clouds come out white, shading to gray where they get thick enough to block the light. What those droplets are and how they got up there is the how a cloud forms lesson's story, and how much of the dome they are covering has its own page. This page only cares about the blue part between them.

The glass-of-sky experiment

This one waits for a day when the sky is actually doing the thing: deep blue overhead, paler at the edges. Not a forecast of blue. Blue, now, so you can check your work against the real ceiling.

You need a flashlight, a okta of cloud. Full sun.">clear glass or straight-sided jar of water, and a little milk. Before anything switches on, make two predictions and write them down: what color will the water look from the side of the glass, and what color will the beam look where it comes out the far end? Same? Different? Commit.

Now stir in a few drops of milk, just enough to make the water faintly cloudy. Those milk specks are going to play the part of the air. Take the glass somewhere dim and shine the flashlight through it. Look from the side. Then get low and look at the light coming out the far end, toward the flashlight but off to the side of the beam.

Now compare notes with your predictions. From the side, the water leans pale blue-gray: you are seeing the short waves knocked sideways, a pocket sky. End-on, the beam comes through warm and yellowish orange: you are seeing what is left after the blue is stolen, a pocket sunset. Then take the whole idea outside and test the real thing. Predict first: which will be bluer, straight overhead or just above the rooftops? Look up, look out, and check. And you now hold a promise for this evening: watch the west at sunset and you will see the far end of the glass, scaled up to the whole sky.

A question for the grown-up to ask, with no right answer attached: where is the bluest part of the sky right now, and why do you think it lives there? The rock has watched this experiment run overhead every clear day for about a billion years and reports that the answer has never once changed, which it considers a strength.

Words in this lesson

Every marked word above is here in full, because a definition that only appears on hover is no use to somebody reading on a phone, printing the page, or listening to it.

Clear

adjective say it: KLEER

Zero to one okta of cloud. Full sun.

Okta

noun say it: OK-tuh

One eighth of the sky. Sky cover is counted in oktas, from zero for clear to eight for overcast, which is why the familiar sky words are really just bands of a number.

Rainbow

Sunlight refracted through rain opposite the sun. Always a full circle; the ground hides half.

Definitions in this explainer follow the National Weather Service. The rock checked twice. The rock always checks twice.

Take it to class

This explainer is free for classrooms: print it, copy it, staple it. The rock asks only that the weather stay accurate.

Download the lesson (PDF) Download the worksheet (PDF)

Questions people actually ask

Grounded in National Weather Service definitions; suitable for classrooms and other curious humans.

Lake-effect snow happens when very cold air blows across a relatively warm, unfrozen lake. The lake heats and moistens the bottom of the cold air, that air rises, and the moisture comes down as snow in narrow bands parked downwind of the shore. The classic forecasters' rule of thumb wants the lake surface about 13 degrees Celsius, roughly 23 degrees Fahrenheit, warmer than the air about a mile up. The longer the stretch of open water the wind crosses, called the fetch, the harder the machine runs, and the wind direction decides exactly which neighborhood gets buried.

A machine with two ingredients

Most snowstorms need a whole storm system. Lake-effect snow needs only a temperature argument: frigid air on the move, and a large body of water that has not frozen and still remembers autumn. Cross the second with the first and the lake runs like a snow machine, no storm system required, often under a sky that is okta of cloud. Full sun.">clear a county away.

It works because water gives up its heat slowly. Deep water that spent all summer warming is still comparatively warm in December, while the air arriving from the interior of a continent can be brutally cold. The mismatch is the fuel.

The recipe, step by step

Cold air slides over the open water. The lake immediately goes to work on the lowest layer of it, warming it and loading it with evaporated moisture. Warm moist air under cold air is exactly the unstable arrangement that convection loves: the heated layer rises in columns, the columns build clouds, and the clouds organize into long narrow bands lined up with the wind.

While the air is over water, the bands just gather strength. When they cross the downwind shore, the land slows the wind, the air piles into itself and gets an extra upward shove, and the bands unload. Snowfall inside a well built band can come down at rates that bury a town in a day, with thunder in the heaviest cases, while the sky ten miles either side of the band stays blue. Lake-effect snow is less like a storm than like a firehose: narrow, aimed, and indifferent to everyone it misses.

The 13 degree rule

Forecasters carry a classic rule of thumb for whether the machine turns on: the lake surface should be about 13 degrees Celsius warmer than the air at roughly a mile up, which is about a 23 degree Fahrenheit gap. Less contrast than that and the lake merely steams politely; more, and the rising columns get vigorous enough to organize serious bands. The rule is a threshold for instability, the same ingredient every convective forecast is checking, just measured across a lake instead of an afternoon.

Fetch: the length of the runway

The second dial is fetch, the distance of open water the wind crosses. A short hop across a narrow lake collects only a little heat and moisture. A long diagonal run down the full length of a great lake gives the air tens of extra miles to load up, and the band that comes ashore at the far end is a different animal. This is why the geometry of the wind matters as much as its temperature: shift the wind a few dozen degrees and the same lake points its firehose at a completely different town, or, aligned just right down the long axis, builds the single fattest band it can.

Who gets it, and when

The season has a shape. Lake-effect snow peaks in early winter, when the water is still warm from summer and the first truly arctic air arrives: the contrast is never better. As winter grinds on, the lake spends its stored heat, the gap narrows, and if the lake freezes over, the machine loses its fuel supply and shuts down. Ice is the off switch.

Geography writes the rest. The famous snowbelts sit downwind of the Great Lakes for the prevailing cold-season winds, which is why the eastern and southern shores collect what the northern and western shores merely watch. Hills just inland make it worse for themselves: the Tug Hill Plateau, rising east of Lake Ontario, adds its own uphill shove to arriving bands and is one of the snowiest inhabited places in the eastern United States because of it.

Reading a lake-effect day

The forecast tell is specificity. A synoptic storm gets forecast for a region; lake-effect gets forecast for a shore, a corridor, sometimes a set of neighborhoods, with the honest admission that a small wind shift moves the whole prediction. If you live downwind of big water, the numbers to watch are the wind direction, the water temperature, and how cold the air above is about to be. The rock does not live near a great lake, which it considers the lake's loss, but it has reviewed the physics and finds the whole arrangement fair: the lake spends all summer collecting warmth, and all December giving it back with interest.

Words in this lesson

Every marked word above is here in full, because a definition that only appears on hover is no use to somebody reading on a phone, printing the page, or listening to it.

Clear

adjective say it: KLEER

Zero to one okta of cloud. Full sun.

Fetch

noun say it: FECH

The stretch of open water a wind crosses. The longer the fetch, the more heat and moisture the air collects on the trip, which is what turns a cold wind over a lake into a snow machine.

Freeze

verb say it: FREEZ

Air at or below 32 F.

Instability

noun say it: in-stuh-BIL-ih-tee

The condition where air, once nudged upward, keeps rising on its own because it stays warmer than its surroundings. It is one of the three ingredients every thunderstorm needs.

Lake-effect snow

noun say it: LAYK ih-fekt SNOH

Cold air over warm lakes builds narrow intense snow bands.

Okta

noun say it: OK-tuh

One eighth of the sky. Sky cover is counted in oktas, from zero for clear to eight for overcast, which is why the familiar sky words are really just bands of a number.

This is a Working lesson

It belongs to the Weather School, which is free and always will be: twenty lessons from toddler to adult, every one with a printable worksheet and answer key that any classroom may copy. No account, no cost, no catch.

Another one at this level: feels like.

For teachers and every lesson.

Definitions in this explainer follow the National Weather Service. The rock checked twice. The rock always checks twice.

Take it to class

This explainer is free for classrooms: print it, copy it, staple it. The rock asks only that the weather stay accurate.

Download the lesson (PDF) Download the worksheet (PDF)

Questions people actually ask

Grounded in National Weather Service definitions; suitable for classrooms and other curious humans.

The jet stream is a narrow, wandering river of fast wind near the top of the troposphere, roughly five to nine miles up, flowing generally west to east. It forms along the boundary where cold polar air meets warm air from the south, and the sharper that temperature contrast, the faster it blows: NOAA puts typical core winds at 80 to 140 mph, with more than 275 mph possible. Storms ride along it like traffic on a highway, so its bends decide who gets a stormy week and who gets a quiet one. A northward bulge is a ridge, and usually quiet; a southward dip is a trough, and usually not.

A river with no banks

Take the air about five to nine miles up, near the tropopause, and it is not drifting. It is organized into narrow bands of wind moving at highway multiples: NOAA gives 80 to 140 mph as the usual range for jet stream winds, with peaks beyond 275 mph in the strongest winter jets. The bands are thousands of miles long, a few hundred miles wide, and only a mile or two deep. A river is the right picture, complete with meanders, except the banks are made of nothing but temperature difference.

Where it comes from

A jet stream forms along the boundary between air masses with a serious temperature contrast, which is why the main one, the polar jet, lives along the line where cold polar air meets warmer air from the south. The bigger the temperature gap across that line, the harder the upper level winds blow along it. A second, weaker one, the subtropical jet, runs at lower latitudes.

That origin story explains the seasons of the jet itself. In winter the pole is dark and frigid while the tropics barely change, so the contrast is enormous and the jet is at its fastest, diving far south into the United States. In summer the contrast slackens and the jet weakens and retreats north toward Canada, taking its parade of storms with it. Why the flow ends up west to east at all is the same spinning-Earth bookkeeping that bends every long-distance wind, covered in why the wind blows.

Troughs, ridges, and your week

The jet rarely runs straight. It meanders in slow waves, and the waves have names worth knowing, because each one is a weather regime you can feel from the ground.

• A ridge is a northward bulge. Beneath and downstream of it, air tends to sink, and sinking air means fair skies that can persist for days. Summer heat waves are usually a ridge that stopped moving.
• A trough is a southward dip. It swings cold air south, and the region ahead of it, the eastern side, favors rising air, which is the raw material of storms. Winter cold outbreaks are a trough doing exactly what troughs do.

Surface storm systems do not just sit under this river; they are steered by it and fed by it, growing on the rising-air side of a trough and getting carried along at the pace of the flow, generally west to east. This is the machinery behind a pattern every observer eventually notices and this site keeps a whole lesson about: in the middle latitudes, tomorrow's weather usually lives to your west today.

Fast planes and rough rides

The jet stream was a flight discovery as much as a science one, and aviation still budgets around it daily. Fly inside the river heading east and the tailwind hands you free speed, which is why the eastbound leg of a cross country round trip is routinely shorter than the westbound leg on the very same route. Fly along its flanks and you find its other signature: the edges of the jet, where fast air shears past slow air, are a common address for okta of cloud. Full sun.">clear air turbulence, the kind that arrives without a cloud in sight.

What the rock watches

You cannot see the jet stream from a lawn. But you can read its position in a week of weather: storm after storm arriving on the same track means you live under the river just now; a long stretch of unbudging heat means a ridge has parked on you; a sudden cold snap out of season means a trough dug deeper than usual. The rock has never been five miles up and does not intend to start, but it has noticed that its busiest weeks and the river's southern detours are the same weeks. It checked twice.

Words in this lesson

Every marked word above is here in full, because a definition that only appears on hover is no use to somebody reading on a phone, printing the page, or listening to it.

Air mass

noun say it: AIR mas

A huge body of air, hundreds of miles across, that has sat in one place long enough to take on that place's temperature and moisture. Most day to day weather is the story of air masses shoving each other around.

Clear

adjective say it: KLEER

Zero to one okta of cloud. Full sun.

Cold snap

A brief sharp turn cold.

Heat wave

Multiple consecutive days of excessive heat.

Jet stream

noun say it: JET streem

The high-altitude wind river steering weather systems.

Okta

noun say it: OK-tuh

One eighth of the sky. Sky cover is counted in oktas, from zero for clear to eight for overcast, which is why the familiar sky words are really just bands of a number.

Ridge

noun say it: RIJ

A northward bulge in the upper air flow, an elongated area of higher pressure. Air sinks beneath a ridge, bringing quiet, often warm weather that can overstay its welcome.

Tropopause

noun say it: TRO-po-pawz

The boundary at the top of the troposphere where temperature stops falling with height. It acts as a lid, which is why the tops of tall thunderstorms flatten out and spread sideways.

Trough

noun say it: TROFF

A southward dip in the upper air flow, an elongated area of lower pressure. Air rises ahead of a trough, which is why one on the map usually means storms or a cold outbreak is coming.

This is a Working lesson

It belongs to the Weather School, which is free and always will be: twenty lessons from toddler to adult, every one with a printable worksheet and answer key that any classroom may copy. No account, no cost, no catch.

Another one at this level: why the wind blows.

For teachers and every lesson.

Definitions in this explainer follow the National Weather Service. The rock checked twice. The rock always checks twice.

Take it to class

This explainer is free for classrooms: print it, copy it, staple it. The rock asks only that the weather stay accurate.

Download the lesson (PDF) Download the worksheet (PDF)

Questions people actually ask

Grounded in National Weather Service definitions; suitable for classrooms and other curious humans.

Frost forms when a surface cools to freezing and below, and water vapor in the air turns directly into ice crystals on it, skipping the liquid stage. That direct jump is called deposition, and it is why frost grows as feathery crystals instead of frozen droplets. The recipe needs a clear sky and calm air, so the ground can radiate its heat away all night undisturbed. And because official temperature is measured several feet up while the ground runs colder, frost can whiten your lawn on a night the thermometer never admits reached freezing.

Not frozen dew

The natural assumption is that frost is dew that froze after the fact: water beads up on the grass, the temperature slides below 32, the beads harden. That does happen, and it produces little frozen droplets with a glassy look. But it is not frost, and the difference is worth having.

True frost never spends a moment as liquid. When a surface is at or below freezing, water vapor touching it turns directly into ice, molecule by molecule, building crystals on the cold surface the way sugar crystals build on a string. The direct jump from vapor to ice is called okta of cloud. Full sun.">clear night, and it is why frost is not frozen dew.">deposition. It is the reverse of the trick a snowbank pulls in spring when it shrinks for days without ever making a puddle.

Crystals built molecule by molecule come out as structure: ferns, feathers, spikes, the white fur on the car roof. That architecture is why frost sparkles and frozen dew merely glistens. The sparkle is the tell that the liquid step was skipped.

The recipe: clear, calm, and long

All day the ground soaks up sunshine. All night it radiates that heat away at the sky. Whether frost forms is mostly a question of whether anything interferes with the radiating, which gives the recipe three ingredients:

• A clear sky. Clouds catch outgoing heat and send some back down, working exactly like a blanket. Under an open sky the ground's heat leaves for space with nothing in the way, and surfaces cool hard. This is radiational cooling, and a long autumn night gives it hours to work.
• Calm air. Wind stirs the coldest air at the surface back in with milder air a little higher up, and the mixing keeps the ground from bottoming out. Still air lets a thin, deeply cold layer settle right where the grass lives.
• Moisture, but not too much. There has to be vapor in the air to build crystals from. Bone dry air can drop below freezing and leave nothing but a brown, disappointed lawn, which forecasters distinguish as a freeze without frost.

Frost at 37 degrees

Here is the part that gets forecasters accused of lying. Official temperature is measured by instruments standing several feet above the ground. On a clear calm night, the coldest air is not up there; it is in the bottom few inches, pooled on the grass, and it can run well colder than the instrument height. So the morning news can honestly report a low of 36 or 37 while your windshield honestly reports winter. Both are right. They were measuring different altitudes, a few feet apart.

Cold air also behaves like water: it is denser than warm air, and on calm nights it drains downhill and pools in hollows and valley floors. Gardeners on a hilltop and gardeners in the dip below it live in different climates every clear October night, and the dip pays for the view it does not have.

The frosts that matter

Frost earns its forecasts because of what it does to growing things. Ice crystals forming inside plant tissue shred cell walls, which is why frostbitten leaves come up limp and blackened. The stretch between the last frost of spring and the first frost of fall is the growing season, and the Weather Service issues frost advisories and freeze warnings in those shoulder weeks precisely because one calm clear night can end a garden that took a whole summer to build.

The defense is the same physics run in reverse. Covering plants at dusk traps the ground's outgoing heat under the cover, a private cloud for one tomato bed. The rock, which does not grow anything and has never once been harmed by frost, still admires the trick: it is the only weather problem a bedsheet reliably solves.

Reading the morning

Frost is also a report, if you read it. It writes down where the cold pooled: the frosted stripe at the bottom of the yard, the clear patch under the tree that acted as a blanket, the white car roof facing open sky while the one under the carport stayed grey. One lawn, one night, and a complete map of how heat moved while you slept. The rock reads it every cold morning and has yet to find a typo. If the night's cooling only got as far as liquid drops, you get dew instead, and that story is told in the dew point lesson.

Words in this lesson

Every marked word above is here in full, because a definition that only appears on hover is no use to somebody reading on a phone, printing the page, or listening to it.

Clear

adjective say it: KLEER

Zero to one okta of cloud. Full sun.

Deposition

noun say it: dep-uh-ZISH-un

Water vapour turning straight into ice without ever being liquid in between. It is how frost builds its crystals on a cold clear night, and it is why frost is not frozen dew.

Freeze

verb say it: FREEZ

Air at or below 32 F.

Frost

noun say it: FROST

Surface ice crystals near 32 F. Kills tender plants.

Okta

noun say it: OK-tuh

One eighth of the sky. Sky cover is counted in oktas, from zero for clear to eight for overcast, which is why the familiar sky words are really just bands of a number.

Radiational cooling

noun say it: ray-dee-AY-shun-ul KOO-ling

The ground losing its heat to the night sky. On a clear, calm night nothing blankets the loss or stirs warmer air back down, so surfaces cool hard; clouds or wind slow the drain.

This is a Foundation lesson

It belongs to the Weather School, which is free and always will be: twenty lessons from toddler to adult, every one with a printable worksheet and answer key that any classroom may copy. No account, no cost, no catch.

Another one at this level: chance of rain.

For teachers and every lesson.

Definitions in this explainer follow the National Weather Service. The rock checked twice. The rock always checks twice.

Take it to class

This explainer is free for classrooms: print it, copy it, staple it. The rock asks only that the weather stay accurate.

Download the lesson (PDF) Download the worksheet (PDF)

Questions people actually ask

Grounded in National Weather Service definitions; suitable for classrooms and other curious humans.

Fresh snow is mostly air: a loose pile of six sided crystals full of tiny pockets and passages. Sound waves that wander into those pockets bounce around and get soaked up instead of reflected, so a snow covered street works like the padded wall of a recording studio. The hush is temporary. As the snow settles, melts, and refreezes into a hard crust, the surface turns reflective and the world gets loud again, often louder than before the storm.

The hush is real

Step outside during a steady snowfall and the world sounds wrong, in the best way. Traffic softens. Footsteps disappear. Voices stop carrying past the driveway. People describe it as peaceful, or eerie, or churchlike, and every one of them is describing the same physical fact: the ground has stopped throwing sound back.

Fresh snow is mostly air

A snowflake is an ice crystal with six arms and a great deal of empty space between them. Pile up a few billion of them loosely and you get a blanket that is far more air than ice, riddled with tiny pockets and winding passages.

That structure is nearly identical to the acoustic foam lining a recording studio, and it works the same way. A sound wave that hits a hard flat surface, like pavement, bounces off nearly intact and continues its career. A sound wave that hits fresh snow slips into the pockets, ricochets around inside, and spends itself as it goes. Little of it comes back out. The energy is not gone from the universe; it has been shredded into warmth too faint to measure with anything but the silence.

Falling snow helps too

The quiet starts before the ground is even covered. Rain announces every single drop: on the roof, the windows, the leaves. Snowflakes are light, slow, and soft, and they land without comment. So a snowstorm removes the sound of its own precipitation while it lays down a carpet that swallows everything else. It is the only weather that gets quieter the harder it comes down.

Why the quiet does not last

Give the snowbank a day or two and the spell breaks. The crystals settle and weld together, the surface partially melts in the afternoon, and overnight it refreezes into a crust. All those sound trapping pockets close up, and the surface goes from foam back to something closer to tile.

A hard, icy snow surface does not just stop absorbing sound; it reflects it well. That is why a bitter morning after an old snow can sound so strangely crisp, with a train or a barking dog arriving from much farther away than usual. There is often a second accomplice: on cold okta of cloud. Full sun.">clear mornings a layer of warmer air can sit above the cold air at the ground, and that arrangement bends rising sound back down toward your ears instead of letting it escape upward. Hard crust below, bent sound above, and suddenly the whole county is audible.

Listening as observation

Which means your ears are a weather instrument. A muffled world says fresh, dry, fluffy snow, the kind that is mostly air, the kind worth a forecast that verified. A loud, crisp, carrying world says the snow is old and crusted, and the sidewalk will be ice before it is slush. The rock cannot hear, strictly speaking, but it has sat through enough winters to endorse the method: when the world goes quiet, look up. Something is falling.

Words in this lesson

Every marked word above is here in full, because a definition that only appears on hover is no use to somebody reading on a phone, printing the page, or listening to it.

Clear

adjective say it: KLEER

Zero to one okta of cloud. Full sun.

Okta

noun say it: OK-tuh

One eighth of the sky. Sky cover is counted in oktas, from zero for clear to eight for overcast, which is why the familiar sky words are really just bands of a number.

This is a Foundation lesson

It belongs to the Weather School, which is free and always will be: twenty lessons from toddler to adult, every one with a printable worksheet and answer key that any classroom may copy. No account, no cost, no catch.

Another one at this level: warm and cold fronts.

For teachers and every lesson.

Definitions in this explainer follow the National Weather Service. The rock checked twice. The rock always checks twice.

Take it to class

This explainer is free for classrooms: print it, copy it, staple it. The rock asks only that the weather stay accurate.

Download the lesson (PDF) Download the worksheet (PDF)

Questions people actually ask

Grounded in National Weather Service definitions; suitable for classrooms and other curious humans.

An air mass is a huge body of air that has sat somewhere long enough to take on that place's temperature and moisture. A front is the boundary where two of them meet. A cold front wedges under the warm air ahead of it and shoves it up fast, so its weather is short, sharp, and followed by clearing. A warm front slides up a long shallow ramp over the cool air ahead, so its weather arrives a day early as thickening clouds and settles in as steady rain. On the map: blue triangles for cold, red half circles for warm, both pointing the way the front is moving.

First, the air mass

Air takes on the personality of whatever it sits over. Park a body of air over central Canada for a week in January and it comes out cold and dry. Let one loaf over the Gulf of Mexico and it comes out warm and loaded with moisture. Each of these is an air mass: a body of air hundreds of miles across that is roughly the same temperature and humidity all the way through.

Most of a continent's day to day weather is the story of these air masses shoving each other around. The interesting part is never the middle of one, where the weather is a rerun. The interesting part is the boundary.

The front is the boundary

Where two air masses meet, they do not blend like creamer into coffee. Cold air is denser than warm air, so the two stay layered and distinct, and the boundary between them is a front. Nearly all of the clouds and precipitation on a weather map are queued up along one front or another, because a front is where air gets lifted, and lifted air is how the sky makes weather.

Which kind of front you get depends on who is advancing.

The cold front: a wedge

When the cold air mass is the one advancing, its dense air stays low and drives under the warm air ahead like a wedge under a door. The warm air has nowhere to go but up, and it goes up hard. Fast lift over a narrow strip means a narrow band of tall clouds, brief heavy rain, often thunder, occasionally the whole thunderstorm recipe at once.

Then it is over. Behind the front the sky okta of cloud. Full sun.">clears, the wind swings around, the pressure rises, and both the temperature and the dew point drop. That scrubbed blue sky the day after a line of storms is the cold air mass showing off. Cold fronts generally move faster than warm ones, which is why their weather is the kind that interrupts an afternoon rather than booking the whole day.

The warm front: a ramp

When the warm air mass advances, it cannot plow the cold air out of the way, because the cold air is heavier and hugs the ground. So the warm air climbs over it, up a ramp so shallow it stretches for hundreds of miles ahead of where the front sits on the map.

That long gentle climb writes a schedule in the sky, and you can read it a day ahead. High thin wisps arrive first, from moist air near the top of the ramp. The clouds then lower and thicken, hour after hour: a milky veil, then a grey sheet, then a dark deck, then rain. Warm front rain is rarely violent. It is steady, wide, and patient, and it can hold the whole day. When the front finally passes, the rain tapers, the air turns warmer and stickier, and the sky may only grudgingly break.

Reading the symbols

• Blue line, triangles. A cold front. The triangles point the way the front is moving, so they point at whoever is about to get the wedge.
• Red line, half circles. A warm front, half circles pointing the way it is headed.
• Alternating red and blue. A stationary front: neither air mass is giving ground. Clouds and rain can camp along one of these for days.
• Purple line, both symbols. An occluded front. Cold fronts travel faster than warm ones, and when a cold front catches the warm front ahead of it, the warm air gets lifted clean off the ground. These usually spiral in near a storm's center.

Read the sky like the map

You do not need the map to know which one is coming. Thickening, lowering clouds that arrive on schedule over many hours are a warm front announcing itself. A hot sticky afternoon with a wall of dark cloud on the western horizon is a cold front about to present its bill. The rock, which has watched this procession from the same spot for roughly a billion years, notes that the fronts have never once changed their manners: the wedge is always rude, and the ramp always writes first.

Words in this lesson

Every marked word above is here in full, because a definition that only appears on hover is no use to somebody reading on a phone, printing the page, or listening to it.

Air mass

noun say it: AIR mas

A huge body of air, hundreds of miles across, that has sat in one place long enough to take on that place's temperature and moisture. Most day to day weather is the story of air masses shoving each other around.

Clear

adjective say it: KLEER

Zero to one okta of cloud. Full sun.

Cold front

noun say it: KOHLD frunt

The leading edge of an advancing cold air mass. Its dense air wedges under the warm air ahead and shoves it up fast, so its weather is short and sharp, followed by clearing skies and drier air.

Front

noun say it: FRUNT

The boundary where two air masses of different temperature and moisture meet. Air gets lifted along a front, which is why most of a map's clouds and rain queue up on one.

Heavy rain

noun say it: HEV-ee RAYN

More than 0.30 inch per hour.

Occluded front

noun say it: uh-KLOO-did frunt

What happens when a faster cold front catches the warm front ahead of it and lifts the warm air clean off the ground. Maps draw it in purple, usually spiraling in near a storm's center.

Okta

noun say it: OK-tuh

One eighth of the sky. Sky cover is counted in oktas, from zero for clear to eight for overcast, which is why the familiar sky words are really just bands of a number.

Stationary front

noun say it: STAY-shun-air-ee frunt

A front where neither air mass is giving ground. The boundary sits still, and clouds and rain can camp along it for days.

Warm front

noun say it: WORM frunt

The leading edge of an advancing warm air mass, sliding up a long shallow ramp over the cooler air ahead. Its clouds arrive high and thin as much as a day early, then lower and thicken into steady, patient rain.

This is a Foundation lesson

It belongs to the Weather School, which is free and always will be: twenty lessons from toddler to adult, every one with a printable worksheet and answer key that any classroom may copy. No account, no cost, no catch.

Another one at this level: morning frost.

For teachers and every lesson.

Definitions in this explainer follow the National Weather Service. The rock checked twice. The rock always checks twice.

Take it to class

This explainer is free for classrooms: print it, copy it, staple it. The rock asks only that the weather stay accurate.

Download the lesson (PDF) Download the worksheet (PDF)

Questions people actually ask

Grounded in National Weather Service definitions; suitable for classrooms and other curious humans.

Thunderstorms need three ingredients: moisture to fuel them, instability so rising air keeps rising, and lift to start the rising. With all three, a storm runs a three stage life: a towering cumulus of pure updraft, a mature stage where updraft and rain cooled downdraft coexist and the weather peaks, and a dissipating stage where the downdraft wins and the storm exhales itself apart. Add wind shear and storms organize, live longer, and turn severe.

The three ingredients

• Moisture. Water vapor is the fuel. When it condenses into cloud, it releases the heat that keeps the storm's engine running. Humid, high dew point air is a loaded pantry.
• Instability. Warm air near the ground under colder air aloft means a lifted parcel stays warmer than its surroundings and accelerates upward, like a beach ball released underwater.
• Lift. Something must start the rise: a front plowing under warm air, a sea breeze, a mountain slope, or the outflow of an earlier storm. No trigger, no storm, even with a loaded sky.

The life of a storm

Stage one is the towering cumulus: a muscular updraft building the cloud tens of thousands of feet in under an hour. Stage two is maturity: precipitation becomes heavy enough to drag a cold downdraft to the ground while the updraft still feeds, and this coexistence delivers the storm's peak: heaviest rain, lightning, hail if the updraft is strong, gusty outflow. Stage three is collapse: the downdraft chokes off the updraft's warm inflow, the fuel line closes, and the storm rains itself out, often within thirty to sixty minutes of maturity.

What makes a storm severe

The fourth ingredient is wind shear: winds changing speed and direction with height. Shear tilts a storm so its downdraft no longer lands on its own updraft, letting the engine run for hours instead of minutes, and in strong shear the updraft itself can begin to rotate, producing supercells, the storms responsible for most giant hail and violent tornadoes. Officially, severe means hail an inch or larger or gusts of 58 mph or more.

Respecting the product

Every thunderstorm manufactures lightning, and lightning outruns rain: strikes can hit ten miles from the rain shaft, ahead of or behind the storm. The rule is boring and correct: when thunder roars, go indoors, and stay half an hour past the last rumble. The rock stays out in everything, but the rock has been struck before and describes the experience as clarifying.

Words in this lesson

Every marked word above is here in full, because a definition that only appears on hover is no use to somebody reading on a phone, printing the page, or listening to it.

Cumulus

noun say it: KYOO-myuh-lus

A heaped, cauliflower cloud built by rising air. Given enough moisture and lift it can grow into a shower or a thunderstorm.

Dew point

noun say it: DOO point

The temperature air must cool to before its moisture starts condensing. It is an absolute measure of how much water the air holds, which is why it beats relative humidity for judging how a day will feel.

Downdraft

noun say it: DOWN-draft

Air sinking through a storm, dragged down by falling precipitation and by evaporative cooling. When a downdraft cuts off its own updraft, the storm collapses.

Front

noun say it: FRUNT

The boundary where two air masses of different temperature and moisture meet. Air gets lifted along a front, which is why most of a map's clouds and rain queue up on one.

Gust

noun say it: GUST

A brief spike above the sustained wind.

Instability

noun say it: in-stuh-BIL-ih-tee

The condition where air, once nudged upward, keeps rising on its own because it stays warmer than its surroundings. It is one of the three ingredients every thunderstorm needs.

Supercell

noun say it: SOO-per-sel

A rotating storm with a mesocyclone. Produces the giant hail and violent tornadoes.

Thunderstorm

noun say it: THUN-der-storm

Any storm producing thunder and lightning.

Updraft

noun say it: UP-draft

The column of rising air inside a storm. It carries moisture upward and holds precipitation aloft until it grows too heavy.

Wind shear

noun say it: WIND sheer

Wind changing speed or direction with height.

This is a Working lesson

It belongs to the Weather School, which is free and always will be: twenty lessons from toddler to adult, every one with a printable worksheet and answer key that any classroom may copy. No account, no cost, no catch.

Another one at this level: layers of the atmosphere.

For teachers and every lesson.

Definitions in this explainer follow the National Weather Service. The rock checked twice. The rock always checks twice.

Take it to class

This explainer is free for classrooms: print it, copy it, staple it. The rock asks only that the weather stay accurate.

Download the lesson (PDF) Download the worksheet (PDF)

Questions people actually ask

Grounded in National Weather Service definitions; suitable for classrooms and other curious humans.

Sky cover is measured in oktas: eighths of the dome above you covered by cloud. Zero to one okta is clear or sunny, one to two is mostly clear, three to five is partly cloudy, six to seven is mostly cloudy, and eight is overcast. The words are bands over a number, which is why two forecasts can describe one sky differently at the edges.

Grading in eighths

Observers, and now satellites and models, divide the sky into eight imaginary slices and count how many are hidden by cloud. That count, zero through eight, is the okta. Every familiar sky word is just an okta range wearing clothes.

The official bands

• Clear or sunny: zero to one okta. The sun operates unopposed.
• Mostly clear, mostly sunny: one to two oktas. A cloud or two, allowed on aesthetic grounds.
• Partly cloudy, partly sunny: three to five oktas. The sky is half committed, and both phrasings are legal.
• Mostly cloudy: six to seven oktas. Sun cameos only.
• Overcast: eight oktas. A full gray ceiling, wall to wall.

Why apps disagree about one sky

A five okta sky sits on the border between partly and mostly cloudy, and different providers round differently, sample different hours, or blend different models. Neither app is lying; both are translating a number near a boundary into words that only change at boundaries. Day versus night phrasing adds more wobble, since partly sunny needs a sun to be partly.

Cloud cover and your plans

High thin cirrus can cover eight oktas and still cast usable sunlight, while a single towering cumulus can own the afternoon. Pair the coverage word with cloud height and thickness when it matters: photographers chase interesting partly skies, solar panels prefer low okta counts, and stargazers want zero and are rarely accommodated.

Words in this lesson

Every marked word above is here in full, because a definition that only appears on hover is no use to somebody reading on a phone, printing the page, or listening to it.

Clear

adjective say it: KLEER

Zero to one okta of cloud. Full sun.

Sunny

adjective say it: SUN-ee

Zero to one okta of cloud. Full sun.

Cumulus

noun say it: KYOO-myuh-lus

A heaped, cauliflower cloud built by rising air. Given enough moisture and lift it can grow into a shower or a thunderstorm.

Mostly clear

adjective say it: MOHST-lee KLEER

One to two oktas of cloud.

Mostly cloudy

adjective say it: MOHST-lee KLOW-dee

Six to seven oktas. More cloud than sun.

Okta

noun say it: OK-tuh

One eighth of the sky. Sky cover is counted in oktas, from zero for clear to eight for overcast, which is why the familiar sky words are really just bands of a number.

Overcast

adjective say it: OH-ver-kast

Eight oktas. Full gray ceiling.

Partly cloudy

adjective say it: PART-lee KLOW-dee

Three to five oktas. Sun and cloud trade places.

This is a Foundation lesson

It belongs to the Weather School, which is free and always will be: twenty lessons from toddler to adult, every one with a printable worksheet and answer key that any classroom may copy. No account, no cost, no catch.

Another one at this level: dew point.

For teachers and every lesson.

Definitions in this explainer follow the National Weather Service. The rock checked twice. The rock always checks twice.

Take it to class

This explainer is free for classrooms: print it, copy it, staple it. The rock asks only that the weather stay accurate.

Download the lesson (PDF) Download the worksheet (PDF)

Questions people actually ask

Grounded in National Weather Service definitions; suitable for classrooms and other curious humans.

Feels like numbers model how fast your body gains or loses heat, not a second secret temperature. In heat, humidity slows the evaporation of sweat, so the heat index runs above the thermometer. In cold, wind strips away the thin warm layer your body builds, so wind chill runs below it. Both are physiology math wearing a weather costume.

One body, two enemies

Your body constantly sheds heat to stay near 98.6. How fast that shedding works depends on more than air temperature: moisture controls whether sweat can evaporate, and wind controls whether your personal bubble of warmed air gets to stay. The feels like figure folds those effects into a single number a human can act on.

Heat index: humidity taxes your sweat

Evaporating sweat is the body's premier cooling technology, and it needs dry air to accept the vapor. As humidity rises the acceptance slows, heat leaves you more slowly, and the effective temperature climbs. At 90 degrees, the National Weather Service heat index sits near 91 with 40 percent humidity, near 100 at 60 percent, and about 105 at 70 percent. Same thermometer, three different afternoons.

Wind chill: wind steals your blanket

In cold, your body warms a millimeters thin layer of air against the skin. Wind peels that blanket off and replaces it with fresh cold air, over and over, accelerating loss. The modern wind chill formula, calibrated on actual humans walking in a wind tunnel, turns 30 degrees with a 5 mph breeze into about 25, and the same 30 with a 30 mph wind into roughly 15. The thermometer never moved; your heat budget did.

What feels like is for

These numbers exist to time decisions: when outdoor work needs breaks and water, when recess moves inside, when exposed skin risks frostbite. They assume shade and a walking pace, so full sun or hard labor makes reality harsher than the number. The rock, which neither sweats nor shivers, still endorses the math on your behalf.

Words in this lesson

Every marked word above is here in full, because a definition that only appears on hover is no use to somebody reading on a phone, printing the page, or listening to it.

Heat index

noun say it: HEET IN-deks

What temperature plus humidity feels like. Caution to extreme danger.

Wind chill

noun say it: WIND chil

What wind makes the cold feel like on skin.

This is a Working lesson

It belongs to the Weather School, which is free and always will be: twenty lessons from toddler to adult, every one with a printable worksheet and answer key that any classroom may copy. No account, no cost, no catch.

Another one at this level: lake effect snow.

For teachers and every lesson.

Definitions in this explainer follow the National Weather Service. The rock checked twice. The rock always checks twice.

Take it to class

This explainer is free for classrooms: print it, copy it, staple it. The rock asks only that the weather stay accurate.

Download the lesson (PDF) Download the worksheet (PDF)

Questions people actually ask

Grounded in National Weather Service definitions; suitable for classrooms and other curious humans.

A watch means conditions are favorable for a hazard: the ingredients are gathering, so get ready. A warning means the hazard is happening, about to happen, or highly likely: act now. An advisory means conditions are less serious than warning criteria but still hazardous enough to cause trouble if you ignore them. One question separates the first two: are the ingredients gathering, or is it here?

The one question that sorts them

Every one of these headlines answers the same question at a different point in time: how close is the hazard to you, right now?

A watch is about ingredients. The atmosphere has assembled what a storm needs, over an area, over a window of hours. Nothing has happened yet and nothing may. The Weather Service is telling you to make your plan while making a plan is still easy.

A warning is about the event. It is occurring, it is imminent, or the odds are high enough that waiting is the wrong move. Warnings are usually smaller in area and shorter in time than watches, because by then the Weather Service knows where.

An advisory is about a hazard that will not meet warning criteria but can still hurt you or ruin your day: the stratus. Light, moderate, and dense grades.">Drizzle that freezes on contact with cold surfaces.">freezing drizzle that glazes an overpass, the heat that stacks up on someone working outside, the fog that removes the car in front of you.

Why people mix up watch and warning

The words do not carry their meanings. Nothing in the sound of "watch" says early and wide, and nothing in "warning" says here and now. The Weather Service knows this: its own public surveys found that people confuse the two, and that "advisory" was the least understood term of the three, often mistaken for a watch.

A trick that survives panic: watch the sky, warn the family. Watch means keep looking. Warning means go tell everybody and move.

The change that has been announced

The Weather Service has said it will retire the "advisory" headline, along with "special weather statement", and replace them with plain language headlines that name the hazard first in capitals, followed by what, where, when, and the impacts. Watch and warning stay exactly as they are, with the same criteria.

That change has been announced, not completed. On the day this page was written the national alert feed carried 78 active advisories, including 44 heat advisories, so the term is still very much in service. When it does change, this page changes with it.

What to do with each one

• Watch. Decide now what you would do, while you have time and daylight. Charge things. Know where you would shelter. Do not cancel your life; do build the exit.
• Warning. Do the thing you decided during the watch. This is not the moment to look out the window and form an opinion.
• Advisory. Adjust. Leave earlier, drive slower, drink water, check on whoever is outside in it.

The rock has one advantage over all of this: it only reports what is happening at the rock, right now. The Weather Service has the harder job of telling you what is coming, which is why its words are worth learning.

Words in this lesson

Every marked word above is here in full, because a definition that only appears on hover is no use to somebody reading on a phone, printing the page, or listening to it.

Drizzle

noun say it: DRIZ-ul

Fine drops under 0.02 inch across, usually from stratus. Light, moderate, and dense grades.

Freeze

verb say it: FREEZ

Air at or below 32 F.

Freezing drizzle

noun say it: FREE-zing DRIZ-ul

Drizzle that freezes on contact with cold surfaces.

Front

noun say it: FRUNT

The boundary where two air masses of different temperature and moisture meet. Air gets lifted along a front, which is why most of a map's clouds and rain queue up on one.

Stratus

noun say it: STRAY-tus

A flat, featureless layer cloud that forms in stable air. It brings drizzle rather than downpours.

This is a Foundation lesson

It belongs to the Weather School, which is free and always will be: twenty lessons from toddler to adult, every one with a printable worksheet and answer key that any classroom may copy. No account, no cost, no catch.

Another one at this level: sky cover.

For teachers and every lesson.

Definitions in this explainer follow the National Weather Service. The rock checked twice. The rock always checks twice.

Take it to class

This explainer is free for classrooms: print it, copy it, staple it. The rock asks only that the weather stay accurate.

Download the lesson (PDF) Download the worksheet (PDF)

Questions people actually ask

Grounded in National Weather Service definitions; suitable for classrooms and other curious humans.

The atmosphere is sorted into five layers by what the temperature does as you climb: troposphere, stratosphere, mesosphere, thermosphere, exosphere. Temperature falls, then rises, then falls, then rises again, and each reversal marks a boundary called a pause. Almost all weather happens in the troposphere, the thin bottom layer whose ceiling sits anywhere from just under four miles up at the poles to twelve miles up at the equator.

Five layers, sorted by temperature

The layers are not stacked by height so much as by behavior. NOAA identifies five distinct layers using thermal characteristics, chemical composition, movement, and density, and separates them with boundaries called pauses, where those characteristics change fastest. The shorthand that actually helps: every time the temperature stops doing one thing and starts doing the opposite, you have crossed into a new layer.

The troposphere: the only layer that rains

Almost all weather occurs here. It starts at your feet, and its ceiling depends on where you are standing. NOAA gives three anchors: the troposphere is 11 to 12 miles (18 to 20 km) high at the equator, 5 and a half miles (9 km) at 50 degrees north and south, and just under four miles (6 km) high at the poles.

Temperature falls with height the whole way, from an average of about 62 F (17 C) near the surface to -60 F (-51 C) at the top. That falling temperature is what permits cumulus cloud, every shower and every thunderstorm.">convection. Air warmed near the ground is less dense than the colder air sitting above it, so it can rise, and rising air is the engine behind every cloud, every shower, and every thunderstorm the rock has ever sat through.

The tropopause: the lid

At the top of the troposphere the cooling stops. Above that boundary the temperature starts increasing with height, which puts warmer air on top of cooler air, and that arrangement shuts vertical motion down. There is no upward push left to give.

You can see the lid with your own eyes. When a thunderstorm's updraft runs out of buoyancy near the tropopause, it spreads sideways instead of upward, and that spreading is the flat anvil top on a big storm. The sky is showing you exactly where one layer ends.

The stratosphere: warm on top, and 19 percent of the air

The stratosphere runs from the tropopause, somewhere between 4 and 12 miles (6 to 20 km) up depending on latitude, to around 31 miles (50 km). It holds 19 percent of the atmosphere's gases and very little water vapor. Its temperature climbs from that -60 F (-51 C) at the tropopause to a maximum of about 5 F (-15 C) at the top. The warming comes from the making of ozone: heat is produced in the process of ozone formation, and that heat is what raises the temperature with height. The boundary at the top is the stratopause.

The mesosphere: where meteors end

From around 31 miles (50 km) to 53 miles (85 km). Temperature falls again with height, or said the other way, it rises as you descend, reaching about 5 F (-15 C) near the bottom. The gases here are thin, but by now they are thick enough to slow a meteor until it burns, which is the fiery trail you see at night. The stratosphere and the mesosphere together are called the middle atmosphere, and the top of the mesosphere is the mesopause.

The thermosphere: hot without being warm

From about 53 miles (85 km) to 375 miles (600 km). Incoming high energy ultraviolet and X-ray radiation from the sun gets absorbed by molecules here, and the temperature climbs hard: from as low as -184 F (-120 C) at the bottom to as high as 3,600 F (2,000 C) near the top.

Which sounds lethal, and is not, at least not for that reason. Temperature describes how much energy the individual molecules are carrying. Up here there are so few molecules that the total heat they could hand you would not be enough to warm skin. It would feel bitterly cold. The rock offers this as proof that a number and a sensation are two different animals, which is the same lesson the dew point teaches at ground level.

The exosphere: the door

From about 375 miles (600 km) out to roughly 6,200 miles (10,000 km). Atoms and molecules escape into space from here, and satellites orbit through it. The transition layer at its bottom is the thermopause. Past the exosphere there is nothing left to sort.

What a forecaster actually uses

Mostly one boundary. The height of the tropopause sets the ceiling on how tall a storm can build, so a storm that reaches it and punches a bump slightly past it, an overshooting top, is a storm with a serious updraft underneath. The rest of the column is scenery. Excellent scenery. It simply does not rain.

Words in this lesson

Every marked word above is here in full, because a definition that only appears on hover is no use to somebody reading on a phone, printing the page, or listening to it.

Convection

noun say it: kun-VEK-shun

Warm air rising because it is less dense than the cooler air above it. It is the engine behind every cumulus cloud, every shower and every thunderstorm.

Cumulus

noun say it: KYOO-myuh-lus

A heaped, cauliflower cloud built by rising air. Given enough moisture and lift it can grow into a shower or a thunderstorm.

Exosphere

noun say it: EK-so-sfeer

The outermost fringe of the atmosphere, where air thins gradually into space rather than stopping at any line.

Mesosphere

noun say it: MEZ-o-sfeer

The layer above the stratosphere, where temperature falls again. It is where most meteors burn up.

Stratosphere

noun say it: STRAT-o-sfeer

The layer above the troposphere, where temperature rises with height because ozone absorbs solar energy. That rising temperature suppresses vertical motion, which is why flying up there is usually smooth.

Thermosphere

noun say it: THER-mo-sfeer

A very thin layer high above the mesosphere where temperature rises sharply. The air is so sparse that the temperature would not feel hot to skin.

Thunderstorm

noun say it: THUN-der-storm

Any storm producing thunder and lightning.

Tropopause

noun say it: TRO-po-pawz

The boundary at the top of the troposphere where temperature stops falling with height. It acts as a lid, which is why the tops of tall thunderstorms flatten out and spread sideways.

Troposphere

noun say it: TRO-po-sfeer

The bottom layer of the atmosphere, where almost all weather happens. Its ceiling runs from just under four miles at the poles to about twelve at the equator.

Updraft

noun say it: UP-draft

The column of rising air inside a storm. It carries moisture upward and holds precipitation aloft until it grows too heavy.

This is a Working lesson

It belongs to the Weather School, which is free and always will be: twenty lessons from toddler to adult, every one with a printable worksheet and answer key that any classroom may copy. No account, no cost, no catch.

Another one at this level: how radar works.

For teachers and every lesson.

Definitions in this explainer follow the National Weather Service. The rock checked twice. The rock always checks twice.

Take it to class

This explainer is free for classrooms: print it, copy it, staple it. The rock asks only that the weather stay accurate.

Download the lesson (PDF) Download the worksheet (PDF)

Questions people actually ask

Grounded in National Weather Service definitions; suitable for classrooms and other curious humans.

Wind is air moving from higher pressure toward lower pressure. Three forces decide what it actually does: the pressure gradient force pushes it, the Coriolis force bends it right in the Northern Hemisphere and left in the Southern, and friction with the ground drags on it. Push and bend alone would send the wind running parallel to the isobars forever. Friction is what makes air spiral into lows, which forces that air to rise, which is the whole reason a low on the map means clouds.

The push

Air has weight, and it does not press down equally everywhere. Where it presses harder you have high pressure. Where it presses less you have low. Air moves from the one to the other for the same reason a full sink drains: a difference exists, and nature has no sentimental attachment to keeping it.

On a weather map that difference is drawn as isobars, lines along which the pressure is the same. NOAA states the rule plainly: the closer the isobars are drawn together, the quicker the air pressure changes, and the speed of the wind is directly proportional to that pressure gradient. Isobars jammed tight mean a windy day. You can read a map's wind before you read a single number on it.

The bend

If the push were the only force, wind would run straight from every high to every low, and the weather would be much simpler and considerably worse. It does not, because the Earth is turning underneath it. The Coriolis force, named for Gustav-Gaspard Coriolis, the French scientist who described it mathematically in 1835, deflects moving air to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.

Seen from space the air travels in a straight line. Seen from the ground, which is where you live and where the rock sits, the path is curved, because the ground rotated while the air was in transit. Nothing pushed it sideways. The floor moved.

Push and bend together settle into a truce. The combination causes the wind to blow parallel to straight isobars with high pressure on its right in the Northern Hemisphere. Turn that around and you have a rule you can use standing in a parking lot: put your back to the wind, and in the Northern Hemisphere the low pressure is off to your left.

The drag

Then the ground gets involved. The surface of the Earth is rough, and friction does two things at once: it slows the wind down, and it breaks the truce. A slower wind gets bent less, so the push wins by a margin, and the air stops running parallel to the isobars and starts cutting across them. NOAA credits friction directly with causing the diverging winds around highs and the converging winds near lows.

Rough ground drags harder than smooth water, so the same pressure pattern does not produce the same wind at a shoreline that it produces over a forest. Friction is also why the wind usually calms after sunset and picks up again mid morning: the air near the ground stops mixing with the faster air above it overnight, and starts again once the sun stirs the pot.

Why lows are cloudy and highs are not

Follow the spiralling air and the rest of the forecast falls out of it.

Into a low, air converges. It cannot pile up, because mass cannot be created or destroyed in a given area, so it has to go somewhere, and the only direction left is up. Rising air cools. When air cools, dew point, and it is the moment a cloud becomes visible.">condensation begins to exceed evaporation, the invisible vapor turns into cloud, and the cloud eventually turns into precipitation. That is why inclement weather keeps company with low pressure.

Around a high, surface air spreads outward, and air from above sinks to replace it. Sinking air warms. Warming air evaporates its own clouds. That is the kind of afternoon nobody writes a lesson about, and the rock enjoys it enormously.

The small wind: a coastline arguing with itself

Not all wind starts with a continental pressure map. The sun's rays penetrate deep into water, spreading the heating through a large volume, but on land they are confined to the top few inches of soil. So land heats faster and cools faster than water does, and by afternoon the air over land is warmer and less dense, forming a weak low that NOAA calls a thermal low. Cooler, denser air over the water is pulled down by gravity and spreads inland underneath it. That is a sea breeze.

The leading edge is called a sea breeze front and it behaves like a small air mass. Its dense air wedges under the warm air ahead and shoves it up fast, so its weather is short and sharp, followed by clearing skies and drier air.">cold front: NOAA notes the temperature can drop as much as 15 to 20 F (8 to 11 C) once it passes, with a shift in wind and a jump in humidity to match. It happens at any large body of water, the Great Lakes included, which is why a lakefront can be twenty degrees cooler than a town ten miles inland on the same afternoon.

One last thing, about names

Wind is named for where it comes from, never for where it is going. A west wind at 15 mph is arriving from the west, not heading toward it. This trips up nearly everybody once. The rock recommends getting it wrong early, and in private.

If you want the numbers that go with the direction, the sustained wind and the gust are two different measurements doing two different jobs.

Words in this lesson

Every marked word above is here in full, because a definition that only appears on hover is no use to somebody reading on a phone, printing the page, or listening to it.

Air mass

noun say it: AIR mas

A huge body of air, hundreds of miles across, that has sat in one place long enough to take on that place's temperature and moisture. Most day to day weather is the story of air masses shoving each other around.

Cold front

noun say it: KOHLD frunt

The leading edge of an advancing cold air mass. Its dense air wedges under the warm air ahead and shoves it up fast, so its weather is short and sharp, followed by clearing skies and drier air.

Condensation

noun say it: kon-den-SAY-shun

Water vapour turning back into liquid droplets. It happens when air cools to its dew point, and it is the moment a cloud becomes visible.

Dew point

noun say it: DOO point

The temperature air must cool to before its moisture starts condensing. It is an absolute measure of how much water the air holds, which is why it beats relative humidity for judging how a day will feel.

Front

noun say it: FRUNT

The boundary where two air masses of different temperature and moisture meet. Air gets lifted along a front, which is why most of a map's clouds and rain queue up on one.

Isobar

noun say it: EYE-so-bar

A line on a weather map joining places at equal air pressure. The closer isobars are drawn together, the stronger the wind between them.

Pressure gradient

noun say it: PRESH-er GRAY-dee-unt

How sharply air pressure changes across a distance. A steep gradient means a strong wind, which is why closely spaced lines on a pressure map mean it is blowing hard.

This is a Working lesson

It belongs to the Weather School, which is free and always will be: twenty lessons from toddler to adult, every one with a printable worksheet and answer key that any classroom may copy. No account, no cost, no catch.

Another one at this level: jet stream.

For teachers and every lesson.

Definitions in this explainer follow the National Weather Service. The rock checked twice. The rock always checks twice.

Take it to class

This explainer is free for classrooms: print it, copy it, staple it. The rock asks only that the weather stay accurate.

Download the lesson (PDF) Download the worksheet (PDF)

Questions people actually ask

Grounded in National Weather Service definitions; suitable for classrooms and other curious humans.

The sun is highest, and its energy strongest, at solar noon. The temperature keeps rising for hours after that, because the ground goes on soaking up more energy than it gives back. The peak arrives at the moment those two finally match, which the National Weather Service puts at several hours following noon. The same trick runs at the scale of a year: the hottest weeks come after the summer solstice, not on it.

The sun is not the thermometer

The National Weather Service says it directly: the warmest part of the day usually occurs several hours following noon, when the sun is highest in the sky. The reason is that sunlight does not heat the air much on its way through it. Sunlight heats the ground. The ground then heats the air touching it, and passing heat along takes time.

So the thermometer is always reporting on something that already happened. It is reading the ground's mood, and the ground is slow.

A bathtub with the drain open

Picture the ground as a bathtub. Sunlight is the tap. The heat the ground radiates back out is the drain, and the drain never closes, not for one second, day or night.

All morning the tap runs harder than the drain empties, so the water level, which is the temperature, rises. At solar noon the tap is at full blast. But the tap does not shut off at noon. It only eases. And as long as it is still delivering more than the drain is taking away, the level keeps going up.

The temperature stops rising at the exact moment the two match. After that the drain wins, and the level falls all evening and all night, reaching bottom right around sunrise, just before the tap comes back on.

Solar noon is not clock noon

There is a second delay hiding inside the first one. The sun reaches its highest point at solar noon, and solar noon almost never lands on 12:00 on your phone.

Time zones are wide, so a town near the eastern edge of one sees the sun peak well before a town near the western edge, even though both clocks read the same. Daylight saving time then shifts the clock another hour on top of that. So through a summer afternoon across much of the country the sun is highest closer to one in the afternoon than to noon, and the temperature peak slides later along with it.

What moves the peak around

• Clouds. An afternoon deck of cloud turns the tap down early, and the high arrives early with it.
• A front. Cold air arriving at two in the afternoon ends the argument on the spot. The day's high may turn out to have been at eleven in the morning.
• Wind off water. A sea breeze can set the high in the late morning at the beach while the temperature is still climbing five miles inland. Same county, different days.
• Rain. The cold outflow from a thunderstorm can drop the temperature in minutes and never give it back.

Which is why the daily high is a fact about the day, not an appointment. It happens when it happens, and then the record keepers write it down.

The same trick, but bigger

Stretch the idea across a whole year and you get the seasonal version of it. The most direct sun in the Northern Hemisphere arrives at the June solstice, but the hottest weeks come later, because, as NOAA's climate data center puts it, the rate of heat input from the sun during the day continues to be greater than the cooling at night for several weeks after that.

It is the same bathtub. It is just a much larger tub, and this time the ground and the oceans are the tub.

Go check it yourself

You do not have to take the rock's word for any of this. Put a thermometer somewhere shaded, out of the wind and off the pavement, and write the reading down every hour on the next clear day. The curve you draw will have the shape of the one above, and the top of it will not be at noon. If you want a shortcut, the hourly forecast on this site will show you the same hump.

The rock has run this experiment roughly every day of its life and gets the same answer each time, which it finds reassuring rather than boring.

Words in this lesson

Every marked word above is here in full, because a definition that only appears on hover is no use to somebody reading on a phone, printing the page, or listening to it.

Clear

adjective say it: KLEER

Zero to one okta of cloud. Full sun.

Front

noun say it: FRUNT

The boundary where two air masses of different temperature and moisture meet. Air gets lifted along a front, which is why most of a map's clouds and rain queue up on one.

Okta

noun say it: OK-tuh

One eighth of the sky. Sky cover is counted in oktas, from zero for clear to eight for overcast, which is why the familiar sky words are really just bands of a number.

Solar noon

noun say it: SO-ler NOON

The moment the sun sits highest in the sky. It is when incoming energy peaks, which is not the same moment as when the air is warmest.

Thunderstorm

noun say it: THUN-der-storm

Any storm producing thunder and lightning.

This is a Foundation lesson

It belongs to the Weather School, which is free and always will be: twenty lessons from toddler to adult, every one with a printable worksheet and answer key that any classroom may copy. No account, no cost, no catch.

Another one at this level: sky cover.

For teachers and every lesson.

Definitions in this explainer follow the National Weather Service. The rock checked twice. The rock always checks twice.

Take it to class

This explainer is free for classrooms: print it, copy it, staple it. The rock asks only that the weather stay accurate.

Download the lesson (PDF) Download the worksheet (PDF)

Questions people actually ask

Grounded in National Weather Service definitions; suitable for classrooms and other curious humans.

The wind speed in a forecast is the sustained wind, which the National Weather Service defines as the average of observed values over a two minute period. A gust is something more specific: rapid fluctuations in the wind speed with a variation of 10 knots or more between the peaks and the lulls, and the gust number itself is the maximum instantaneous speed. Both are measured about 10 meters (33 feet) above open ground, which is a large part of why the forecast disagrees with your back yard.

Two numbers doing two different jobs

The first number, the plain wind speed, is an average. The National Weather Service defines gusts inside it.">sustained wind as the wind speed determined by averaging observed values over a two minute period. Two minutes is long enough to smooth out the fidgeting and report what the air is broadly doing.

The second number is the opposite kind of measurement. A wind gust, in the Weather Service's own words, is rapid fluctuations in the wind speed with a variation of 10 knots or more between peaks and lulls, and the gust speed is the maximum instantaneous wind speed. Read that carefully, because it is the part people miss: a gust is not simply a windier moment. It is a specific amount of unsteadiness. If the air is briskly and evenly moving, with no real gap between its peaks and its lulls, nothing gets reported as a gust at all.

In the national forecast grids the pairing is spelled out even more plainly. Wind speed is the expected sustained wind at 10 meters for that hour. Wind gust is the maximum 3 second wind speed forecast to occur within a 2 minute interval at a height of 10 meters. An average across two minutes, and the worst three seconds inside it.

Ten meters up, standing in the open

Both numbers describe a standard place, not your place. The measurement height is 10 meters, which is about 33 feet, over open ground with nothing crowding it.

Your yard is not that. It has a fence, a house, a hedge, and a neighbor's garage, and every one of them slows the air down near the surface. So a forecast of 15 mph can read like almost nothing behind the house, and like 25 out on the ridge above it. The forecast is not lying to you. It is answering a question about a bare field 33 feet up, and you are asking a question about your patio.

Knots, briefly

Observations often come in knots. One knot is one nautical mile per hour, which works out to about 1.15 mph. So the 10 knot gust criterion is a swing of roughly 11 and a half mph between the lull and the peak. That is a real jolt, not a wobble, which is exactly why the threshold exists.

What each speed looks like outside

The Weather Service publishes a table of visual clues so that anyone can estimate wind without owning an instrument. A few anchors worth memorizing, straight off it:

• 4 to 7 mph. Wind felt on the face. Leaves rustle and small twigs move.
• 13 to 18 mph. Small branches move. Dust and loose paper get lifted and driven along the ground.
• 25 to 31 mph. Large branches in continuous motion. Whistling in overhead wires. Umbrellas used with difficulty.
• 39 to 46 mph. Twigs and small branches break off. Walking is generally impeded.
• 55 to 63 mph. Considerable structural damage, especially to roofs. Small trees blown over and uprooted.

The slider below has the whole table in it. The rock recommends learning three or four of these by heart, because they work when the phone is dead.

Why the gust is the number that matters

Damage comes from the peak, not the mean. The push that moving air exerts rises with the square of its speed, so doubling the wind roughly quadruples the force. A 50 mph gust does not hit twice as hard as a 25 mph wind. It hits about four times as hard.

There is a second reason, and it is about you rather than physics. A steady wind is something you can lean into and plan around. A gust arrives before you can do either. It is what takes down the tree limb that was managing fine, tips the high sided truck, flips the trampoline, and gets the patio umbrella into the neighbor's pool. The rock has never once been blown over and still watches every one of these events with interest.

When wind is expected to become a genuine hazard, the Weather Service says so with a headline, and the thresholds for those headlines are set locally rather than nationally. Which headline means prepare and which one means act is covered in watch, warning, advisory.

Direction, one more time

Wind is named for the direction it comes from. A north wind at 20 mph is arriving out of the north. If you want the machinery behind that arrow, why the wind blows covers the push, the bend, and the drag.

Words in this lesson

Every marked word above is here in full, because a definition that only appears on hover is no use to somebody reading on a phone, printing the page, or listening to it.

Gust

noun say it: GUST

A brief spike above the sustained wind.

Knot

noun say it: NOT

One nautical mile per hour, the unit aviation and marine forecasts use. A knot is about 1.15 miles per hour.

Ridge

noun say it: RIJ

A northward bulge in the upper air flow, an elongated area of higher pressure. Air sinks beneath a ridge, bringing quiet, often warm weather that can overstay its welcome.

Sustained wind

noun say it: sus-TAYND WIND

The wind speed averaged over a period rather than caught at an instant. Reporting stations typically average two minutes, which is why sustained wind is always lower than the gusts inside it.

This is a Foundation lesson

It belongs to the Weather School, which is free and always will be: twenty lessons from toddler to adult, every one with a printable worksheet and answer key that any classroom may copy. No account, no cost, no catch.

Another one at this level: why snow is quiet.

For teachers and every lesson.

Definitions in this explainer follow the National Weather Service. The rock checked twice. The rock always checks twice.

Take it to class

This explainer is free for classrooms: print it, copy it, staple it. The rock asks only that the weather stay accurate.

Download the lesson (PDF) Download the worksheet (PDF)

Questions people actually ask

Grounded in National Weather Service definitions; suitable for classrooms and other curious humans.

The dew point is the temperature the air would need to cool to for its moisture to start condensing. It measures how much water vapor is actually in the air, which is what your skin cares about. Below the mid 50s feels dry, the 60s turn sticky, and anything in the 70s is tropical. Unlike relative humidity, dew point does not change its story every time the temperature moves.

What the number means

Cool a parcel of air and its ability to hold water vapor shrinks. The dew point is the temperature where that shrinking ability finally matches the moisture already present, and condensation begins: dew on grass, fog in valleys, sweat that will not dry. More moisture in the air means a higher dew point. That is the whole trick.

Why it beats relative humidity

Relative humidity compares moisture to what the air could hold at its current temperature, so it swings wildly as the day warms and cools without a single drop of moisture changing. A desert dawn can read 85 percent humidity and feel wonderful; a Gulf Coast afternoon can read 55 percent and feel like soup. Dew point ignores the drama. A dew point of 72 feels like 72 dew point weather at any hour, in any state.

Phoenix versus Miami

Ninety degrees with a dew point of 40 is dry heat: sweat evaporates instantly and cooling works. Ninety with a dew point of 75 shuts the machine down; the air is too full of moisture to accept much more, so sweat sits on the skin and the heat compounds. Same thermometer, different planets. This is also why heat index tables need two inputs, not one.

Reading your own weather

Watch the dew point line in the forecast the way you watch temperature. Falling dew points behind a front mean crisp relief even if the thermometer barely moves. A dew point crossing 70 on a summer evening promises a sweaty night and fuel for any storms that find the trigger. The air is telling you its plans; dew point is the sentence that matters.

Words in this lesson

Every marked word above is here in full, because a definition that only appears on hover is no use to somebody reading on a phone, printing the page, or listening to it.

Condensation

noun say it: kon-den-SAY-shun

Water vapour turning back into liquid droplets. It happens when air cools to its dew point, and it is the moment a cloud becomes visible.

Dew point

noun say it: DOO point

The temperature air must cool to before its moisture starts condensing. It is an absolute measure of how much water the air holds, which is why it beats relative humidity for judging how a day will feel.

Front

noun say it: FRUNT

The boundary where two air masses of different temperature and moisture meet. Air gets lifted along a front, which is why most of a map's clouds and rain queue up on one.

Heat index

noun say it: HEET IN-deks

What temperature plus humidity feels like. Caution to extreme danger.

Relative humidity

noun say it: REL-uh-tiv hyoo-MID-ih-tee

How full of moisture the air is compared with the most it could hold at that temperature. It moves when the temperature moves even if no water is added or removed, which is why it misleads people about comfort.

This is a Foundation lesson

It belongs to the Weather School, which is free and always will be: twenty lessons from toddler to adult, every one with a printable worksheet and answer key that any classroom may copy. No account, no cost, no catch.

Another one at this level: hottest part of the day.

For teachers and every lesson.

Definitions in this explainer follow the National Weather Service. The rock checked twice. The rock always checks twice.

Take it to class

This explainer is free for classrooms: print it, copy it, staple it. The rock asks only that the weather stay accurate.

Download the lesson (PDF) Download the worksheet (PDF)

Questions people actually ask

Grounded in National Weather Service definitions; suitable for classrooms and other curious humans.

A 60 percent chance of rain means: given this setup, measurable rain (at least 0.01 inch) is expected at any given point in the forecast area 60 times out of 100. Formally it is confidence multiplied by coverage. It says nothing about how long it rains, how hard it rains, or which hour it picks.

The formula behind the percent

The National Weather Service defines the probability of precipitation, PoP, as a simple product: the forecaster's confidence that measurable rain will happen somewhere in the area, multiplied by the share of the area expected to get it. Confidence times coverage.

Two very different days can both be a 60: a forecaster certain (100 percent) that storms will soak 60 percent of the region, and a forecaster only 75 percent sure that rain will cover 80 percent of it. Both multiply to 0.6, so both are announced as 60 percent.

What the percent is not

• Not a share of your day. A 60 percent chance does not mean rain for 60 percent of the time. A ten minute downpour and a nine hour stratus. Light, moderate, and dense grades.">drizzle can carry the same number.
• Not intensity. The percent says nothing about how hard. A 20 can flood a basement; a 90 can be a polite sprinkle.
• Not a guarantee either way. A 20 percent day rains one time in five. One in five is common. Ask any picnic.

Why small percents still bite

A 20 percent chance sounds dismissible, but it usually means the ingredients for rain exist and coverage will be spotty. Somebody wins that lottery. If you are moving hay, pouring concrete, or painting a fence, the question is not whether the number is small; it is whether you can afford to be the winner.

How to actually use it

Read the percent alongside the sky it comes with. A 60 attached to scattered afternoon thunderstorms means plan the morning and keep an exit for later. A 60 attached to an approaching front means the whole day leans wet. The number is the odds; the forecast text is the plot.

Words in this lesson

Every marked word above is here in full, because a definition that only appears on hover is no use to somebody reading on a phone, printing the page, or listening to it.

Drizzle

noun say it: DRIZ-ul

Fine drops under 0.02 inch across, usually from stratus. Light, moderate, and dense grades.

Front

noun say it: FRUNT

The boundary where two air masses of different temperature and moisture meet. Air gets lifted along a front, which is why most of a map's clouds and rain queue up on one.

Downpour

noun say it: DOWN-pour

More than 0.30 inch per hour.

Sprinkle

noun say it: SPRING-kul

Up to 0.10 inch per hour.

Probability of precipitation

noun say it: prob-uh-BIL-ih-tee of pre-sip-ih-TAY-shun

The forecaster's confidence multiplied by the share of the area expected to get wet. It is the odds of measurable rain at any given point, and it says nothing about how long or how hard.

Stratus

noun say it: STRAY-tus

A flat, featureless layer cloud that forms in stable air. It brings drizzle rather than downpours.

Thunderstorm

noun say it: THUN-der-storm

Any storm producing thunder and lightning.

This is a Foundation lesson

It belongs to the Weather School, which is free and always will be: twenty lessons from toddler to adult, every one with a printable worksheet and answer key that any classroom may copy. No account, no cost, no catch.

Another one at this level: dew point.

For teachers and every lesson.

Definitions in this explainer follow the National Weather Service. The rock checked twice. The rock always checks twice.

Take it to class

This explainer is free for classrooms: print it, copy it, staple it. The rock asks only that the weather stay accurate.

Download the lesson (PDF) Download the worksheet (PDF)

Questions people actually ask

Grounded in National Weather Service definitions; suitable for classrooms and other curious humans.

Radar sends microwave pulses and times the echoes that bounce back off precipitation. It measures what is falling through the air, not what is reaching your shoes: the beam rises with distance, so far from the radar it can only see rain a mile or more overhead. Most radar illusions, like dry ground under a colorful blob, come from that gap between the beam and the ground.

Pulses, echoes, and colors

A weather radar spins slowly, sending out pulses of microwave energy and listening. When a pulse hits raindrops, snowflakes, or hail, part of the energy reflects home. Distance comes from the delay; intensity comes from how much energy returns. Big drops and hailstones reflect ferociously, which is why the colors climb from green through yellow to red as precipitation gets heavier.

The beam looks up

The lowest radar scan is tilted about half a degree above level, and the Earth curves away beneath it. Both effects lift the beam higher above the ground the farther it travels. Close to the radar it samples air a few hundred feet up; a hundred miles out, it is sampling weather more than a mile and a half overhead. Everything below the beam is invisible to it.

The classic lies

• Virga. Rain paints the screen but evaporates in dry air on the way down. The radar honestly saw rain; the rain simply never finished the trip.
• The leading edge. An approaching storm slings rain forward aloft. Radar paints your neighborhood minutes before the first drop lands, which is why the map can disagree with your dry driveway while thunder is already audible.
• okta of cloud. Full sun.">clear day.">Ground clutter. Near the radar, the beam clips buildings, ridges, even flocks of birds, and draws them as weather. Modern filters catch most of it.
• Under the beam. Far from the radar, shallow stratus. Light, moderate, and dense grades.">drizzle or snow can slide beneath the beam entirely: dry screen, wet ground. The opposite lie.

Reading radar like the rock does

Treat radar as testimony about the air, not a verdict about the ground. Animate it: motion tells you whether that blob is a threat or a memory. Check intensity trends rather than single frames. And when the map and your window disagree, believe the window. The rock has held this position for roughly a billion years and sees no reason to soften it.

Words in this lesson

Every marked word above is here in full, because a definition that only appears on hover is no use to somebody reading on a phone, printing the page, or listening to it.

Clear

adjective say it: KLEER

Zero to one okta of cloud. Full sun.

Drizzle

noun say it: DRIZ-ul

Fine drops under 0.02 inch across, usually from stratus. Light, moderate, and dense grades.

Ground clutter

noun say it: GROWND KLUT-er

Radar returns from buildings, hills and trees near the antenna rather than from weather. It is why a radar map can show a permanent smudge over a city on a clear day.

Okta

noun say it: OK-tuh

One eighth of the sky. Sky cover is counted in oktas, from zero for clear to eight for overcast, which is why the familiar sky words are really just bands of a number.

Ridge

noun say it: RIJ

A northward bulge in the upper air flow, an elongated area of higher pressure. Air sinks beneath a ridge, bringing quiet, often warm weather that can overstay its welcome.

Stratus

noun say it: STRAY-tus

A flat, featureless layer cloud that forms in stable air. It brings drizzle rather than downpours.

Virga

noun say it: VER-guh

Rain that evaporates before reaching the ground.

This is a Working lesson

It belongs to the Weather School, which is free and always will be: twenty lessons from toddler to adult, every one with a printable worksheet and answer key that any classroom may copy. No account, no cost, no catch.

Another one at this level: thunderstorm recipe.

For teachers and every lesson.

Definitions in this explainer follow the National Weather Service. The rock checked twice. The rock always checks twice.

Take it to class

This explainer is free for classrooms: print it, copy it, staple it. The rock asks only that the weather stay accurate.

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