The 5th Annual Flash Flood and Intense Rainfall Experiment: Evaluating Emerging Atmospheric and Hydrologic Guidance to Improve WPC's Excessive Rainfall Outlooks

The 5th Annual Flash Flood and Intense Rainfall (FFaIR) Experiment was held at the Weather Prediction Center (WPC) Hydrometeorology Testbed (HMT) in College Park, MD over four weeks during the period from June 19 to July 21. The FFaIR Experiment brings together participants from across the weather enterprise to simulate a pseudo-operational environment in an effort to create experimental probabilistic forecasts and evaluate emerging models, tools, and datasets with the ultimate goal of improving flash flood forecasting. During the experiment, participants utilized the latest experimental, deterministic, convection allowing models (CAMs) and CAM ensemble systems in concert with experimental hydrologic guidance to create experimental forecasts. Subjective and objective data were collected from evaluations and analysis of the experimental guidance and forecasts. A major theme for the 2017 FFaIR Experiment was to determine the skill of high resolution CAMs in the Day 2 and Day 3 time periods.

The 2017 FFaIR Experiment evaluated ways to test the skill of high resolution CAMs through longer forecast periods and high resolution CAM ensembles for short-term flash flood forecasts, evaluated new and experimental hydrologic guidance from the National Water Model, and further explored proposed changes to WPC’s operational Excessive Rainfall Outlook (ERO), including methodologies to verify them. For this experiment, the numerical values associated with the categorical risk thresholds were increased for experimental EROs, and the forecasts were verified with multiple verification inputs for the first time. This presentation will give an overview of the 2017 FFaIR Experiment and highlight results of how the longer-range CAM forecasts performed, how the experimental EROs verified compared to the operational EROs, as well as include feedback on hydrologic guidance and CAM ensembles that were evaluated during the experiment.