The Climatology, Vulnerability, and Public Perceptions Associated with Overlapping Tornado and Flash Flood Warnings in a Portion of the Southeast United States

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Abstract Simultaneous and overlapping tornadoes and flash floods are a meteorological hazard with complex societal implications as, when issued at the same time, tornado and flash flood warnings provide conflicting public safety advice. This work assessed potential tornado and flash flood (TORFF) events in a portion of the Southeast from an interdisciplinary perspective with a focus on the climatology, vulnerability, and public perceptions surrounding these hazards. Our results suggest that, in addition to the conflicting warning advice, TORFFs present a challenge to the public because they can occur at night or in cool seasons when they are least expected, though they are most common in spring. Also, the storms causing TORFFs are often not clearly organized, causing a forecast and communication challenge. The public responding to the tornado and flash flood warnings in our study area is more vulnerable to TORFFs than those in other areas and may lack vehicles and structures to respond safely to one or both hazard threats. Administered survey results suggest that many believe they know what protective actions to take in a TORFF, though they may not believe they are likely in their area. Those that believe they are likely are also more likely to feel prepared to respond. Many climatology and vulnerability characteristics vary between, and at times within, NWS county warning areas, highlighting the different communication and preparation needs across the region. Approximately a quarter of flash flood and tornado warnings overlap in the region for an average of 31 min. The frequency of TORFFs and their associated public safety challenges warrant continued investigation. Significance Statement The purpose of this work is to increase our understanding of overlapping tornado and flash flood events by studying them from a multidisciplinary perspective. We found that residents in the southeastern United States are especially vulnerable to overlapping tornado and flash floods. This vulnerability is heightened by the climatology of overlapping tornado and flash floods because they can occur when they are unexpected, for example, at night or in the winter, and the public perceptions of overlapping tornado and flash floods, which is that they may not be likely in their area. These findings are important because much of the Southeast includes a population vulnerable to overlapping tornado and flash floods who may be underestimating their risk, and therefore may be unprepared for an event that requires critical decision-making.