Development of a Database of Flash Flood Events in the US

For several reasons our understanding of flash floods and their impacts is limited. Short lead times, localized areas of impact, and confusion over what events are defined as flash floods, our flash flood knowledge is primarily based on detailed post-event investigations. Much remains to be known about the spatial extent, frequency, and magnitude, i.e. climatology, of flash floods. What kinds of novel methods can be introduced to complete our understanding of the spatial and temporal characteristics of flash floods, ultimately leading to flash flood climatologies?

The Severe Hazards Analysis and Verification Experiment (SHAVE) has been underway at the National Severe Storms Laboratory since 2006. The experiment uses radar-based decision products to identify regions potentially impacted by severe weather including hail, wind, tornadoes, and flash floods. The products are displayed in real-time using Google Earth along with digital telephone databases. A team of undergraduate meteorology students calls potentially impacted residences and polls them about the severity of weather being experienced. All information is entered into a digital database through a web-based form. This study describes the data collection methodology and presents preliminary findings from > 2500 flash flood reports that were collected during the summer of 2008. We encourage other agencies worldwide to develop coordinated data collection strategies of flash floods, with future consideration of societal impacts in the questionnaires.