Forecast, each 12 hours
Chance of rain
For
The chance of rain or snow in each 12 hours, day and night, for seven days: when to expect it, and how surely.
0100%
Forecast map / Forecast, each 12 hours
Thunderstorm chance forecast map
Over Santa Clara, California, where the map opens. The whole country
The chance of a thunderstorm in each 12 hours for seven days: where storms are likely, before any radar sees them. 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 thunder map shows
The chance of a thunderstorm in each 12 hours for seven days, in percent: where storms are likely to form, before any radar can see them.
How to read it
- Under 15%
- Storms unlikely.
- 15 to 30%
- An isolated storm or two.
- 30 to 55%
- Scattered storms.
- Over 55%
- Storms likely; numerous where the chance runs highest.
What it is for
- Plan around lightning: outdoors, on the water, in the mountains.
- See the days a severe outbreak may come.
- Read with the radar once the storms form.
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=fts, the times of its frames.
In the Field Book
- ThunderstormFB-EVT-001
- SupercellFB-EVT-007
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
Reflectivity
Radar
Latest
Rain, snow and hail across the country now, from every radar in the national network, a new picture every five minutes.
1070 dBZ
Echo tops
Storm tops
Latest
How tall each storm stands, in feet: the higher the top, the stronger the storm and the more likely hail and wind.
560,000 ft