To address these deficiencies, the NWS Colorado Basin RFC has developed a set of GIS-based Flash Flood Potential (FFP) indicators for several WSR-88D radar umbrellas in the Western United States, including for those within the NWS Salt Lake City WFO (SLC) County Warning Area (CWA). A variety of static GIS raster data layers that include information about basin terrain features, vegetation, forest cover, land use (specifically for urbanization effects), and soil characteristics have been created to produce ten discrete levels corresponding to increased risk of flash flooding. The newly classified layers are weighted and combined, resulting in a static set of flash flood indicators that describe an area’s relative potential for flash flooding. Although currently available on a hardware platform separate from the operational workstation platform used to run FFMP, forecasters at SLC have benefited from this additional information in the flash flood warning decision making process for the past two flash flood seasons.
This paper will document the added value of using the FFP to enhance the information provided by FFMP, especially to reduce flash flood warning false alarm rates. Several case studies are presented to demonstrate its usefulness in the flash flood warning decision making process at WFO SLC. Plans for future enhancements to the FFP will also be described, including adding dynamic layers to account for other flash flood factors such as antecedent basin soil moisture and wildfire burn impacts. Also possible is the addition of a dynamic atmospheric flash flood potential layer currently under development at WFO SLC using neural network techniques.