Tornado Warnings, Lead Times, and Tornado Casualties: An Empirical Investigation

Abstract

Conventional wisdom holds that improved tornado warnings will reduce tornado casualties, because longer lead times on warnings provide extra opportunities to alert residents who can then take precautions. The relationship between warnings and casualties is examined using a dataset of tornadoes in the contiguous United States between 1986 and 2002. Two questions are examined: Does a warning issued on a tornado reduce the resulting number of fatalities and injuries? Do longer lead times reduce casualties? It is found that warnings have had a significant and consistent effect on tornado injuries, with a reduction of over 40% at some lead time intervals. The results for fatalities are mixed. An increase in lead time up to about 15 min reduces fatalities, while lead times longer than 15 min increase fatalities compared with no warning. The fatality results beyond 15 min, however, depend on five killer tornadoes and consequently are not robust.

Current Efforts for Prediction and Assessment of Natural Disasters: Earthquakes, Tsunamis, Volcanic eruptions, Hurricanes, Tornados, and Floods

“…Simmons and Sutter [183] examined how the number of casualties, injuries, and fatalities in a tornado event is reduced when warnings are emitted with longer lead times. The impact of false alarms on warnings and casualties in tornadoes is studied by Simmons and Sutter [184].…”

Using PBL to Prepare Educators and Emergency Managers to Plan for Severe Weather

“…With an average lead time of 11 minutes (Simmons & Sutter, 2008), having learners learn during a real event is not feasible or safe. We referred to the literature and looked for examples where people were trained to solve problems in an emergency.…”

“…The facilitator distributed the cards one at a time instead of leaving the cards for the entire activity at each table, a decision that defined the sequence of instruction and also controlled the pace of the game. Participants were only given five minutes to make decisions because average lead time is 11 minutes (Simmons & Sutter, 2008) but that time would include being able to move people to shelters, lock doors, and so on, so decisions had to be made quickly. We were able to see how this kept the game moving during the pilot test and added time pressure to decisions.…”

“…Emergency managers depend on leaders who work with these special populations to understand severe weather procedures and work with them to keep people safe and make decisions proactively and in a timely manner. The average lead time for tornado warnings is 11 minutes (Simmons & Sutter, 2008). Therefore, when planning a response for a tornado, this is the maximum amount of time school decision makers have to get all of their students and staff to safety.…”

“…Schools show both of these characteristics. The average lead time for tornadoes is only 11 minutes (Simmons & Sutter, 2008), so decisions must be made decisively and leaders must be prepared in advance. This paper describes how an instructional design process was used to develop an interdisciplinary problem based learning training for both school personnel and emergency managers.…”