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Sources

Where the facts come from

Every factual claim on this site links to its source. This is the full list.

How we checked

We only use official weather and science sources and specialist research bodies: NOAA (the Storm Prediction Center, the National Severe Storms Laboratory and NOAA Education), the Met Office, TORRO (the Tornado and Storm Research Organisation) and the European Severe Storms Laboratory (ESSL). Each fact was written alongside its source. Our build script stores the source text and, for every fact, checks that the key words and figures really appear in it. 150 of 150 checks passed when this site was last built (31 Oct 2026). Where we couldn’t find one of those sources saying it, we left the claim out.

Things that change

Some figures are averages, lists or records that get updated, such as yearly averages, death tolls and the number of reports in a database. These are marked “checked 31 Oct 2026” so you know how fresh they are. Where two sources put something differently, we show both and say who says what.

The games

Build a tornado uses the ingredients from NOAA NSSL and the Storm Prediction Center, and the Met Office’s four stages; the pictures and timings are made up by the game. EF Catcher uses the Storm Prediction Center’s EF bands; the wind speeds are made up each round and km/h are converted by us. The Tornado Ready Dash answers come from the NOAA and TORRO pages below.

Using the data

We quote published figures with credit. TORRO asks to be credited, and ESSL’s European Severe Weather Database data are not for commercial use, so we only cite figures ESSL has published itself.

All sources (22)