MRMS Radar Explorer

MRMS — NOAA's Multi-Radar/Multi-Sensor system — merges every NEXRAD in the country, plus Canadian radars, satellite, lightning and surface observations, into one national grid at about one kilometre. It is not one radar's picture stitched to its neighbour's: the seams have already been reconciled, so a storm crossing a radar boundary stays one storm.

This page is the NDFD Explorer's instrument pointed at observations instead of forecasts — the same domain hierarchy, the same place-name controls, the same output shapes and the same export path. A sector is a bounding box the map flies to, so one national mosaic serves all of them and you can zoom straight past a sector boundary to your own county.

Move the pointer (or tap) anywhere and the corner readout gives the measured value under it. Unlike the model pages, that number is not recovered by inverting a palette: every frame is stored as 255 levels of the physical quantity and coloured only when a tile is drawn, so the server can be asked what the field actually was. It is also why the colour scale can be changed without re-rendering anything.

The timeline carries observed scans, not forecast periods. Reflectivity publishes about every two minutes and the archive holds three hours, so a loop is a real history rather than a projection. Choosing a longer loop thins the frames rather than piling them up, so a three-hour loop costs a phone no more memory than a fifteen-minute one.

Forecast dBZ is not an official source. For watches, warnings and advisories, always consult weather.gov.