Utilizing Dual-Pol Digital Precipitation Rate to Predict Flash Flooding in Central Kentucky and Southern Indiana

Over the past 30 years, flash flooding has ranked as the #1 deadliest weather hazard in the United States. In the first half of 2019 alone, five fatalities occurred in Kentucky due to flash flooding. The ability to accurately predict these events is critical to the National Weather Service’s goal of protecting life and property. This study investigated the effectiveness of predicting flash flooding in central Kentucky and southern Indiana utilizing Doppler radar dual-polarization digital precipitation rate (DPR). Forty-seven flash flood events from January 2016-February 2019 were collected using the NOAA Storm Events Database and heavy rainfall analysis from the National Centers for Environmental Information (NCEI) Weather and Climate Toolkit. DPR data for each flash flood event was assessed for 2 in/hr, 3 in/hr, and 4 in/hr rain rate thresholds, which produced 6954 potential flash flood data points. These points were compared to local storm reports (LSRs) for flash flooding to determine which points actually verified and the lead time(s) of each point. Lastly, a flash flood potential index (FFPI), which focuses on land surface characteristics (slope and land cover), was used to identify the flood susceptibility for each data point. Results show that areas naturally prone to flash flooding require lower DPR rate thresholds for shorter time durations than areas that are less prone. Critical DPR rate thresholds discovered in this study combined with FFPI will be used by NWS forecasters to improve flash flood detection, warning lead times, and decision support services to promote a Weather Ready Nation.