Tornado Warnings: How Doppler Radar, False Alarms, and Tornado Watches Affect Casualties

The National Weather Service (NWS) began issuing tornado warnings in 1953. Tornado warnings represent the core element of the nation’s efforts to reduce tornado casualties. In addition to warnings, the Storm Prediction Center (SPC) issues tornado watches, and more recently began issuing convective outlooks. Watches alert residents that conditions are favorable for the development of tornadoes, while a warning means that a tornado either has been spotted or has been indicated on radar. The accuracy of tornado warnings has increased over the decades, and with the advent of Doppler weather radar, warnings can now generally be issued

before

a tornado actually touches down. In 2004, the probability of detection (or the proportion of tornadoes warned for) was .69, while the average lead time on tornado warnings was almost 13 minutes.