A Path Toward Short-Term Probabilistic Flash Flood Prediction

Flash flood warning decision making has been based on deterministic products, such as real-time precipitation estimates, flash flood guidance, and hydrologic modeling within the Flooded Locations and Simulated Hydrographs (FLASH) system. These products provide deterministic output and lead to a dichotomous yes/no warning decision by forecasters. The next evolution of flash flood prediction and warnings focus on two advancements: 1) Probabilistic information and 2) high-resolution short-term forecasting.

Evaluations conducted over the last few years within the Multi-Radar Multi-Sensor (MRMS) Hydrometeorology Testbed – Hydro (hereinafter denoted as HMT-Hydro) Experiment explored the application of probabilistic information from the FLASH system into the warning process. Participants used a suite of probabilistic products to issue simulated Flash Flood Warnings (FFWs) that included uncertainty information about the potential magnitude of flash flooding. These products provided probabilities of flash flooding occurrence and portrayed the potential severity of the event. Structured cases focused on the application of ensemble probabilistic precipitation forecasts from the NSSL Warn-on-Forecast system into the probabilistic hydrologic modeling framework.

This presentation discusses recent results from the work conducted in the HMT-Hydro Experiment, as well as the potential path forward for integrating probabilistic flash flood prediction within the Forecasting a Continuum of Environmental Threats (FACETs) paradigm.