The Sixth Annual Flash Flood and Intense Rainfall Experiment: Synthesizing Atmospheric and Hydrologic Guidance for Short Range (6-24 Hour) Probabilistic Excessive Rainfall Forecasts

The 6th 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 18 to July 20, 2018. 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 convection allowing 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 2018 FFaIR Experiment was to synthesize the large amount of both atmospheric and hydrologic guidance to come up with probabilistic short range (6-24 hour) excessive rainfall forecasts.

The 2018 FFaIR Experiment evaluated ways to test the skill of high resolution deterministic CAMs and convection allowing ensemble systems for short-term excessive rainfall forecasts along with using new and experimental hydrologic guidance from the National Water Model. Experimental "first guess" forecasts were evaluated at the Day 1, 2, and 3 ranges as a possible starting point for the WPC operational excessive rainfall outlook (ERO). A new experimental verification system to verify the forecasts used for the first time in 2017 was used again and available in a Geographic Information System (GIS) format. This presentation will give an overview of the 2018 FFaIR Experiment and highlight results of how the experimental deterministic and ensemble CAMS performed, how the experimental EROs verified compared to the operational EROs, as well as include feedback on hydrologic guidance evaluated during the experiment.