Supporting Post-Fire Flash-Flood Warnings with Multi-Sensor Burn Scar Mapping

Wildland fires in the Western United States have increased in both size and number in recent years (Radeloff et al. 2018). With this has come a growing and well documented need for better burn scar maps to help forecasters issue timely warnings for post-fire flash flooding. The Priorities for Weather Research (NOAA Science Advisory Board 2021) reports a need for leveraging diverse data sources (ID-4.5) to improve risk assessment and forecasting of High Impact Weather events, including the NWS vision of Warn-on-Forecast (FO-6.3). NOAA has funded or supported several efforts involving burn scar mapping with satellite observations from Visible Infrared Imaging Radiometer Suite (VIIRS) (Batzli et al. 2018 and Villegas Bravo et al. 2022), GOES-R ABI (Geostationary Operational Environmental Satellite-R, Series Advanced Baseline Imager) (Losos 2022), with others applying research with Sentinel-1A C-Band Synthetic Aperture Radar (SAR) (Michaelides et al. 2021) through initiatives, such as the JPSS and GOES-R Proving Grounds, and other mechanisms, such as the cooperative agreements. All have shown promise at Readiness-Level 2 (applied research), each with strengths and weaknesses. None has yet produced a readily available prototype for systematic testing by NWS Weather Forecast Office hydrologists in their modeling of post-fire flash flood risk as well as supporting the NOAA Weather Prediction Center (WPC). Our vision as a team is to combine our expertise and technical skills and leverage the best qualities of each sensor by integrating our past applied research (Readiness-Level 2) to develop prototype demonstration (Readiness-Level 6) products in a the form of near real-time, data-fused, gridded products suitable for testing in Geographic Information Systems (GIS) and web map services. We are applying the power of cloud computing with Google Earth Engine (Google Cloud) and machine learning to our workflows to reduce latencies and improve quality. The focus is on reducing delays for delivering 1) prototype perimeter updates of burned areas to emergency managers and IMETS (Incident Meteorologists) for better situational awareness and delivering 2) a model input burn scar layer to NWS WPC for Mesoscale Precipitation Discussion (MPD) and to NWS WFO hydrologists responsible for recommending post-fire flash flood warnings, as an earlier input surrogate to the often delayed Burned Area Reflectance Classification (BARC) maps or US Geological Survey (USGS) Landslide Hazards Program maps currently in use.