RTMA Explorer

The Real-Time Mesoscale Analysis is not a forecast. It is NOAA's best estimate of what the surface weather actually was, hour by hour, at 2.5 km over the continental United States — surface observations, radar, satellite and a short-range model background reconciled into one gridded picture. Forecasters verify against it; this page lets you look at it.

Because there is no forecast lead, the timeline runs through the UTC day — twenty-four hourly steps from 00Z, labelled by valid hour rather than by F-number — and the picker above chooses which day of the rolling 30-day archive to look at. Today's day fills in as the analyses land, about fifty minutes after each hour.

Eight fields, drawn from the raw NCEP GRIB2 with no smoothing and no rescaling. Three of them are derived rather than read: relative humidity from the analysed temperature and dewpoint, apparent temperature as the NWS composes it — heat index in warm weather, wind chill in cold, the plain temperature in between — and the wind speed from the same two components the barbs are drawn from, so the colour and the arrows over it cannot disagree.

Colour ramps are pinned to absolute values, so a loop shows real changes rather than a palette re-fitting itself each frame. RTMA is an analysis and not a warning product: for watches, warnings and advisories, the National Weather Service is always the authority.