Flash Flood Severity Index (FFSI): Operational Application in the Field

Flash flooding is one of the deadliest natural hazards in the United States and requires clear communication among forecasters, researchers, emergency managers, and the general public in order to fulfill the mission of the National Weather Service (NWS). Flash flooding is interdisciplinary by nature, so a multifaceted, collaborative approach towards improved forecasting and effective dissemination of life-saving flood information is essential. To optimize the understanding of an individual’s flood risk, knowing how each event compares to another is important because this information provides the community with a more concrete frame of reference regarding local flood hazards. With this in mind, an interdisciplinary approach to this issue was undertaken and resulted in a simple, five-tier, damage-based, post assessment tool: the Flash Flood Severity Index (FFSI). A 2016 Journal of Hydrology study presented the FFSI, and the index was well received by numerous NWS forecasters. To expand the project, an applicability test began in 2018 at three NWS Weather Forecast Offices across Oklahoma and Texas. Preliminary results illustrate the applicability of the FFSI and support the necessity of such an index for the broader weather community and general public. As the inventory of events grows, collaborators aim to further develop the tool and integrate it across the agency to contribute to nationwide efforts towards improved flash flood risk communication.