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
Live/Radar
Live radar
Over Citizen station EW5759, Pennsylvania, where the map opens. The whole country
Radar across the United States, live: the echo and the storms’ tops every five minutes, the rain falling now, and the rain of the last hour to three days in motion. Below them, the forecast maps: seven days of temperature, wind, rain, snow, sky and thunder. Each picture opens on its own page, its own map.
Live radar
Seven pictures of the same storms: where rain and snow are now, how tall the storms stand, how hard it falls, and how much has come down.
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
Falling now
Rain rate
Latest
How hard rain and snow are falling at this moment, in inches of water an hour, a new picture every two minutes.
.014 in an hour
Rain total, 1 hour
Last hour
Latest
All the rain of the last hour, in inches: the quickest way to see where the downpours are falling now.
.0112 in
Rain total, 24 hours
Last day
Latest
The rain of the last 24 hours, in inches: where the heaviest totals of the day fell, and which ground is soaked.
.0112 in
Rain total, 48 hours
2 days
Latest
The rain of the last 48 hours, in inches: a slow storm, or two in a row, added up across the country.
.0112 in
Rain total, 72 hours
3 days
Latest
The rain of the last three days, in inches: a long storm whole, and the totals that lead to river flooding.
.0112 in
Forecast maps
The forecast for the lower 48, to seven days ahead, each playing forward from now on the same map as the radar.
Forecast, hour by hour
Temperature
For
The temperature ahead across the lower 48, hour by hour, for seven days: warm and cold air on the move.
-20110 F
Forecast, each day
Highs
For
The highest temperature of each day for the next seven days: where heat builds and where cold air holds.
-20110 F
Forecast, each night
Lows
For
The lowest temperature of each night for the next seven days: frost, freeze, and warm nights that bring no relief.
-20110 F
Forecast, hour by hour
Wind
For
The wind ahead, in miles an hour, with lines that flow the way it blows: calm, breezy, or strong enough to harm.
075 mph
Forecast, hour by hour
Gusts
For
The strongest gusts ahead, in miles an hour: the brief bursts that bring down limbs and power lines.
075 mph
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 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 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 amount
Snow, 6 hours
For
How much snow will fall in each 6 hours, in inches on the ground: where a storm turns to snow, and how heavy.
.136 in
Forecast total
Snow total
For
All the snow forecast from now to each frame, in inches: a storm’s whole snowfall, and the week’s.
.136 in
Forecast, hour by hour
Sky cover
For
How much of the sky cloud will cover, hour by hour: clear sky is the map itself, the brighter the thicker the cloud.
0100%
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%
How the pictures are made
Every radar in the national network, more than 150 of them, sweeps the sky every few minutes, tilting up through a set of angles. The sweeps are joined into one picture of the country on a grid about a third of a mile across, each place taking the lowest beam that sees it clearly. Each picture is checked against the national analysis before it is drawn, and echo it does not confirm (birds, insects, ground clutter, the beam bent back to the ground) is left out. From the same sweeps, the rain falling now and the rain that has fallen are worked out. Storm Station draws each picture in its own colours, in the browser, at every zoom, so the map stays sharp as it is enlarged.
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.
The same pictures, as tiles: /radar/now.json gives the times of the latest frames, /radar/now.json?show=p24h those of a total, and /radar/now.json?show=ft those of the forecast.