Evaluation of flash flood products from the Flooded Locations And Simulated Hydrographs (FLASH) project

The FLASH project incorporates multiple, contemporary tools and models to assess the impending severity of heavy rainfall and flash flooding. FLASH products have been demonstrated in real time and subsequently evaluated on a subjective basis by National Weather Service Forecasters during the Flash Flood and Intense Rainfall experiment (FFaIR) and the Hazardous Weather Testbed Hydrology experiment (HWT-Hydro). In this study, we present findings from an objective evaluation of the distributed hydrologic modeling approaches that incorporate recent developments in a-priori parameter estimation, improvements in channel routing and model physics, model reanalysis leveraging datasets from the Multi-Year Reanalysis Of Remotely-Sensed Storms (MYRORSS) project, and error models developed for output products. FLASH skill is assessed using a very large dataset of observed flooding as measured by US Geologic Survey (USGS) stream gauges. These skill scores are then compared to traditional flash flood guidance approaches.

In addition to the evaluation, this presentation will provide an overview of the latest advances in the FLASH project including forthcoming impact-specific products, probabilistic forecasts, and forcing from short-term precipitation forecasts. A timeline for the transition of the research products as part of the Mulit-Radar Multi-Sensor system to operations in the National Weather Service will be presented for the various products.