Historical Summer Rainfall and Lightning Events in the Southern Appalachian Mountains

Summertime flash flooding events in the Southern Appalachian Mountains (SAMs) are difficult to adequately predict and can surprise forecasters. The proximity to a warm water source makes this specific mountain range susceptible to rapid, intense rainstorms. Current techniques for predicting these events involve the use of multi-sensor-based quantitative precipitation estimates, but these remotely-sensed observations have proved insufficient for predicting flash flooding. A goal for researchers is to systemize the use of lightning data in anticipating these flash flooding events and provide National Weather Service (NWS) forecasters with a convection-driven algorithm for the SAMs. Previous research suggests severe weather warnings can be improved by 15-20 minutes based on recognized patterns of total lightning.

To investigate the utility of lightning observations for flash flooding nowcasting, a historical summer rainfall and lightning events catalog for the period between July-August of 2018-2022 is being assembled. Data from two research networks located in the SAMs - the Coweeta Hydrologic Lab sub-basin network and the Duke Great Smoky Mountains Rain Gauge Network - combined with WSR-88D rainfall estimates, streamflow observations, storm reports, NWS flash flood warning polygons, and space-based flooding observations, will be included. Lightning data from the GOES-16 Geostationary Lightning Mapper will be collected for several heavy rainfall events. Several storm events will be identified using the synthesized data to demonstrate the value of this catalog to researchers and forecasters.