Who reports
National Weather Service offices collect reports from trained SKYWARN spotters, emergency managers, law enforcement, the media, weather stations and the public, including apps like mPING. Each report has a time, a place and a measurement or estimate.
Daily reports
The Storm Prediction Center (SPC) publishes the day's reports of tornadoes, hail of 1 inch or larger and damaging wind or gusts of 58 mph or more. They're preliminary: duplicates are filtered, but times and sizes can still change.
Storm Data, the final record
Weeks to months later, local offices review their reports for NOAA's Storm Data publication, which SPC compiles into its official database. That's what we use for 2010 through 2025. Times are in Central Standard Time.
Limits to know
- Reports are points. The hail swath between them isn't recorded.
- More people means more reports. Cities have more reports than farmland.
- Wind reports are often damage-based estimates without a measured speed.
How we use them
We measure the distance from every report to your address, group them into storm dates and label recent reports as preliminary. About the data.