May 24 - July 30
Analyzing Tornado Warning Performance Across Storm Lifetimes
Josué Chamberlain, Matt Flournoy, Kenzie Krocak, Harold Brooks and Alex Anderson-Frey
What is already known:
- Isolated tornadoes and the First tornadoes of the day are the most difficult to warn
- The number of tornado warnings peak in mid-afternoon
- Outbreak Tornadoes have a higher probability of detection than isolated tornadoes and are more likely to cause casualties
- Atmospheric conditions favorable to produce tornadoes are highest in outbreak events
- Forced reduction in false alarm ratio decreases probability of detection and lead time
What this study adds:
- The impact of tornado order does influence warning performance
- Geographical regions do not strongly influence Tornado warning performance
- Tornado warning performance is sensitive to the time of day
- The order of the Tornado with its parent storm does influences warning lead time
Abstract:
Tornadoes with inadequate warnings continue to present a threat to the public. In this study, outbreak events from 2008-2010 were gathered from the National Weather Service verification database to analyze their tornado warning performance. Utilizing Google Earth and an online radar viewer, we numbered the parent storms that produced those tornadoes. We then categorized these tornadoes into the order of sequence they were produced, called tornado order, to analyze their warning performance and lead time. Our primary hypothesis in doing this was to see whether the first tornado of every storm was more poorly warned than subsequent tornadoes on each storm. Furthermore, we analyzed differences in tornado-warning performance with respect to geographical region and the diurnal cycle. Our data shows a correlation with tornado order and warning performance. Warning rates and positive lead times increased with subsequent tornadoes after the first tornado. Tornado order with respect to their diurnal cycle showed a substantial difference between diurnal events (which had a better warning rate) and nocturnal events. No significant differences were evident between warning rates in different geographical regions. Our study shows evidence that tornado order and the diurnal cycle impact the warning performance of tornadoes.