Severe Thunderstorm Warnings in Arkansas, 2009

By month

402 of 1,050 severe thunderstorm warnings covering Arkansas in 2009 had a qualifying storm report inside them; 608 of 735 hail, wind and damage reports fell inside a warning, on average 27 minutes after it went out.

Arkansas, 2009

Each office's whole area, 2009

An office's figures cover every county it serves, including across state lines.

Verified by the Iowa Environmental Mesonet's Cow, which matches each storm-based warning with the local storm reports inside its polygon while it was in force, within 15 km of its edge: a tornado warning counts as verified on a tornado report, a severe thunderstorm warning on hail of 1 inch or more, a gust of 58 mph or more, or wind damage, a flash flood warning on a flash flood report. The false alarm ratio is the share of warnings with no such report; "inside a warning" is the probability of detection, the share of reports that fell inside one; lead time runs from the warning's issue to each report inside it, counting zero for a report that came first. A warning with no report is not proof nothing happened: reports come from spotters, the public and damage surveys, and are thin where few people live.