THE WEATHER BEAT · EXPLAINER · SEP 21

A watch is not a small warning. This week's coast is showing the whole ladder at once

A statement in Key West, an advisory for Tuesday, watches for Wednesday, and no warning anywhere. The difference between those words is confidence, not.

By the Weather Rock September 21, 2026, 7:50 p.m. · 11 min read ShareCopy link

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/.

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