While it's happening,
it goes live.
The Storm Desk says what's coming and Past storms shows what happened. Now covers the hours in between: what is falling at each of your places right now, how hard, what the next three hours bring, and what's being reported around you. It switches itself on.
One storm, three views.
A supercell on the Plains or a squall line in the South counts as much as a nor'easter. While it's on, a red dot sits on Now, and on the phone the home screen's "Coming up" card turns into "Happening now".
The answers, first.
Every place gets the same panel, in the same order. Where a source doesn't reach a place, its row says "not available here" instead of disappearing.
Two hours back, three ahead.
The map scrubs from two hours of observed radar, through "now", into three hours of the HRRR's 15-minute forecast, with the seam marked. Rain and snow are drawn in their own colors, so you can watch the mix line move.
- Rate and type · from radar every 2 minutes, nationwide
- The snow line · where rain turns to snow, frame by frame
- Severe storms · their chances, hail size and rotation
- Reports and stations · spotter reports, and the latest from every airport
- Discussions · SPC and WPC, pinned where they apply
A storm is coming. When, and how bad?
Live mode doesn't wait for a forecast storm. When a severe storm heads your way, Now shows when it arrives, the path it's on, and its chances of hail, damaging wind, a tornado and lightning, from the same NOAA guidance National Weather Service forecasters use.
Hail and rotation pushes work even when live mode is off: if a storm with hail or rotation is heading for one of your places, you hear about it.
It tells you, once.
Each push names its place and opens Now there. A changeover sends one push, not one every time the radar flickers. All six are on by default, and any of them can be switched off.
Every 15 minutes, written down.
While live mode is on, each place's type, rate, temperature, totals and reports are logged every 15 minutes. When the storm's over, the log is added to its Past storms review as an "As it happened" card, beside what each model said and what was measured.
Everything is fetched once, nationally, and cut to the places in use, so every US place gets the same page. Outside the US, Now says it isn't available there.
Road cams, pavement temperatures and closures are built and being tested, along with river gauges and coastal tides with their own flood pushes.
Data on this page: NOAA MRMS (precipitation rate, type, radar QPE and lightning probability), NOAA/CIMSS ProbSevere, MESH hail and rotation tracks, NOAA HRRR, NWS Aviation Weather Center (METARs), NWS storm reports and forecast discussions via the Iowa Environmental Mesonet, the Storm Prediction Center and Weather Prediction Center, FAA NAS Status. Pictures are illustrations: the places, map and numbers are made up.