Preparing for Danger: On the Impact of Tornado Watches on Tornado Casualties

We explore the impact of tornado watches on tornado casualties. The time needed to take shelter for a tornado can be as little as a few minutes, but because warning lead times averaged less than 15 minutes in 2004, a watch could alert residents to be ready to receive and respond to a later warning. We find that casualties per tornado are greater for tornadoes occurring within a tornado watch, although this difference vanishes when controlling for tornado, warning, and path characteristics in a regression analysis. We find no evidence that watches reduce casualties, either directly or by increasing the effectiveness of tornado warnings. Tornadoes occurring within watches are more often warned for and warnings reduce casualties, so watches do contribute to lives saved through the warning process.