Improving flash flood communication and decision making: Experts' perceptions of risk and the warning and response process

Because flash floods evolve quickly, timely warning and decision making are critical to saving lives and reducing other negative impacts when a flash flood threatens. The flash flood warning and response process involves interactions among experts — including forecasters, media personnel, and public officials — and members of the public. One challenge for effective risk communication and protective decision making is that the expert groups have different professional expertise and roles, and thus different perspectives on flash flood risk, warning, and response. As part of a larger project aimed at understanding and improving warning decisions in extreme weather events, we studied how NWS forecasters, television and radio broadcasters, and local public officials in the Boulder, Colorado, area perceive flash flood risk and the warning and response process. Although the City of Boulder has not experienced significant flooding in decades, its geography and meteorology place it at high risk for flash flooding, and recent wildfires have exacerbated the risk; there have also been devastating flash floods in nearby communities. Data for the study were collected from individual mental models interviews with 6 NWS forecasters, 6 television and radio broadcasters, and 8 local public officials, and from a group decision modeling session conducted with NWS forecasters. Based on analysis of these data, we explore how members of these groups: 1) conceptualize flash floods (including exposure, effects, and mitigation) and associated uncertainty; 2) create, disseminate, and use flash flood warning information; and 3) perceive how warning information is interpreted and used by others. The data are used to develop a decision-focused model of the flash flood forecast and warning system, which is then used to analyze similarities and differences among the experts. The model is also used in another portion of the project to help examine public perceptions of flash floods. Key themes in the findings will be discussed, focusing on results that are important for improving risk communication for flash floods and extreme weather events more generally.