An Assessment of Real-Time Tornado Information Disseminated through NWS Tornado Warnings and Statements

Previous studies have suggested that real-time confirmation of a tornado specified in National Weather Service (NWS) warnings and statements increases the perceived credibility and urgency of these critical warning messages to the end user, because it represents the highest level of certainty that the hazard is occurring. The timely confirmation of a tornado in official NWS products, announced through multiple sources by private and public partners, is believed to improve overall public response to the tornadic threat, ultimately reducing casualties. This study shows the frequency of NWS products that provide real-time information of ongoing tornadoes, and discusses the implications to NWS operations and external partnerships. Specifically, the findings determine explicit cases when tornadoes are more likely to be reported in real-time and reemphasizes the importance of the initial science-based tornado warning prior to confirmation.

The data set used for this study includes all EF-1 and greater tornadoes in fifteen states located in the central contiguous United States, during a 5-y period from 2007 through 2011. Each confirmed tornado is examined to ascertain whether the tornado was observed and disseminated in NWS tornado warnings and statements in real-time prior to the tornado dissipating. These data are sorted by their EF-scale rating, path length and duration, time of day, geographic region, population density, by fatality, and by number of tornadoes per day to identify contributing factors that may facilitate or hinder the communication of this information.