Forecast amount
Rain, 6 hours
For
How much rain will fall in each 6 hours, in inches, snow as its water: the bands of rain crossing storm by storm.
.0112 in
Forecast map / Forecast, each 12 hours
Chance of rain forecast map
Over Flood Watch for Ketchikan Gateway Borough, Annette Island, Petersburg Borough and 3 more, where the map opens. The whole country
The chance of rain or snow in each 12 hours, day and night, for seven days: when to expect it, and how surely. How to read it.
The rings are the storms the radars detect, the larger ring a severe one; each line runs to where its storm will be in an hour if it keeps its present speed and heading. Rotation and hail are what the radars detect and the analysis measures, not warnings: the official watches and warnings in force are drawn on the map in their own colours and set out in full under Alerts.
What the chance of rain map shows
The chance of at least 0.01 inch of rain or melted snow in each 12 hours, day and night, for seven days. A 70% chance means rain falls at that place on seven of ten days forecast like it.
How to read it
- Under 20%
- Rain unlikely.
- 20 to 40%
- A slight chance; a shower here and there.
- 40 to 60%
- A fair chance.
- 60 to 80%
- Rain likely.
- Over 80%
- Rain nearly certain.
What it is for
- Pick the dry days of the week.
- See a storm system’s timing across the country.
- Read with the rain amount: a high chance of a little rain is not a storm.
How it is made
The forecast maps are drawn from the national blend of the forecast models: the models joined into one forecast and corrected against what each place has measured, on a grid 1.6 miles across, the forecast the country’s forecasters start from. Each of its main runs, four a day, is read whole, laid onto the same grid of latitude and longitude as the radar at 2.8 miles a cell, and played forward from now.
A frame every 12 hours for 7 days, played as a loop of 3 or 7 days. As data: /radar/now.json?show=fpop, the times of its frames.
In the Field Book
- Water vapour as a gasFB-ENG-011
Over a state
AlabamaAlaskaArizonaArkansasCaliforniaColoradoConnecticutDelawareDistrict of ColumbiaFloridaGeorgiaHawaiiIdahoIllinoisIndianaIowaKansasKentuckyLouisianaMaineMarylandMassachusettsMichiganMinnesotaMississippiMissouriMontanaNebraskaNevadaNew HampshireNew JerseyNew MexicoNew YorkNorth CarolinaNorth DakotaOhioOklahomaOregonPennsylvaniaRhode IslandSouth CarolinaSouth DakotaTennesseeTexasUtahVermontVirginiaWashingtonWest VirginiaWisconsinWyoming
With it
Severe AlertsWeather by stateForecast accuracyInstrument atlas
Beside it
Forecast total
Rain total
For
All the rain forecast from now to each frame, in inches: the week’s rain adding up, and where it builds highest.
.0112 in
Forecast, each 12 hours
Thunder
For
The chance of a thunderstorm in each 12 hours for seven days: where storms are likely, before any radar sees them.
080%