Data Sources

The public weather data StormAuditor uses, what each source is best for, and the limitations you should keep in mind.

Primary gridded and radar sources

NOAA MRMS MESH (Multi-Radar Multi-Sensor, Maximum Estimated Size of Hail) provides radar-derived hail size estimates on a roughly 1-km grid — the backbone of the Hail Explorer and hail history products. NOAA URMA/RTMA (the NWS analysis of record) provides hourly gridded wind analysis at 2.5-km resolution, and HRRR model fields supplement recent dates. These grids are analyses and estimates, not point measurements.

Observations and reports

ASOS/AWOS station observations supply measured wind gusts from airport-grade instruments. NWS Local Storm Reports (LSRs) capture spotter, public, and emergency-management reports of hail and wind. NWS warnings (severe thunderstorm, tornado) document what forecasters warned in real time. NCEI Storm Events is the official post-storm record, and FEMA declarations mark federally recognized disasters.

Live radar, satellite, and forecast layers

The free Live Radar & Storm Replay page animates the national NEXRAD composite (via the Iowa Environmental Mesonet's public tile service, in 5-minute frames live and back to 2012 in replay), overlays live NWS warning polygons and the SPC Day-1 categorical outlook, and shows GOES-19 satellite imagery from NOAA NESDIS. The free 7-Day Forecast page serves the official NWS gridded point forecast and active alerts straight from api.weather.gov. These live layers are displayed as published — StormAuditor adds no modeling on top of them.

How sources are combined

Address-level wind estimates blend the URMA background with station gusts and measured storm reports under the SAWE-2 wind methodology. Hail values combine MESH with warnings and reports under the SAHE-2 hail methodology. State pages fuse warnings, reports, NCEI records, and FEMA declarations into deduplicated per-state event streams.

Update cadence and limitations

Most layers update continuously or daily as NOAA publishes them; official NCEI records trail real time by weeks to months. Every source has resolution and coverage limits — read Limitations and Data Disclaimers before relying on any single value, and see the data license for how the aggregated datasets may be reused and cited.

Primary source documentation

Every dataset StormAuditor uses is public and officially documented — verify any layer at the source:

• NOAA NSSL MRMS program — the Multi-Radar Multi-Sensor system behind MESH radar-estimated hail size, with the algorithm lineage in Witt et al. (1998).
• NOAA NCEP RTMA/URMA products — the real-time and un-restricted mesoscale analyses that serve as the NWS analysis of record for surface wind.
• NOAA HRRR model — the High-Resolution Rapid Refresh fields that supplement recent dates.
• NWS ASOS program — the automated airport-grade surface observing network supplying measured gusts (with AWOS operated under FAA standards).
• SPC severe weather reports and NWS Local Storm Reports — spotter, public, and emergency-management reports of hail and wind.
• NCEI Storm Events Database — the official post-storm federal record.
• FEMA disaster declarations — federal recognition of major events.