Limitations

What StormAuditor's data can — and cannot — tell you.

Estimates, not measurements

Almost every value StormAuditor shows is an estimate derived from gridded analyses (URMA at 2.5 km, MRMS MESH at ~1 km), station observations that may sit miles from your property, and human-filed reports. A gridded value is the analysis for an area, not a measurement at your roof. Reports state this plainly and show the distance to supporting evidence.

Storm dates and time zones

Storm dates are local calendar days (midnight to midnight, daylight saving time included). A missing value, an estimate below the reporting thresholds, or no nearby storm reports does not mean hail or wind did not occur.

Specific limits to keep in mind

• Grid resolution: one URMA cell covers several square miles; localized gusts inside a cell can exceed the analysis.
• Station distance: the nearest airport-grade instrument may be 5-20 miles away; conditions between it and your address can differ.
• Warnings are not observations: a severe thunderstorm warning means forecasters expected severe weather in a polygon — not that it occurred at every address inside it.
• Reports trail reality: Local Storm Reports depend on someone reporting; rural areas under-report. Official NCEI records arrive weeks to months later.
• Radar hail is an estimate: MESH estimates the maximum hail size at the ground from radar, calibrated against ground hail reports; individual stones vary.

What StormAuditor never does

It does not determine that damage occurred, assign causation, establish coverage or liability, or certify an official date of loss. Reports are research documentation built from public data under a published methodology. For source-by-source caveats see Data Disclaimers.

Primary source documentation

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

• NWS MRMS documentation — the Multi-Radar Multi-Sensor system behind MESH radar-estimated hail size, with the algorithm lineage in Witt et al. (1998), Weather and Forecasting 13(2), doi:10.1175/1520-0434(1998)013<0286:AEHDAF>2.0.CO;2.
• 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 (Data.gov) — federal recognition of major events.