The National Severe Storms Laboratoryʹs contribution to severe weather warning improvement: multiple-sensor severe weather applications

The National Severe Storms Laboratory (NSSL) has played the primary role in the development and evaluation of U.S. National Weather Service (NWS) severe weather applications for the Weather Surveillance Radar-1988 Doppler (WSR-88D). NSSL developed many of the primary detection algorithms for the radar, and is currently developing improvements to these algorithms. The traditional WSR-88D severe weather algorithms have been designed for use with a single-radar data source. Although the algorithm guidance has led to an improvement of the NWS severe weather warning statistics, it is understood that effective warning decisions can only be made via the integration of information from many sources, including input from multiple remote sensors (multiple radars, mesoscale models, satellite, lightning, etc.). Therefore, these traditional single-radar severe weather algorithms have been updated to take advantage of additional data sources in order to reduce the uncertainty of the measurements and increase the accuracy of the diagnoses of severe weather. SL Warning Decision Support System-Integrated Information (WDSS-II) has provided an invaluable development environment to facilitate the development of these new applications. In just 1 year (2002), NSSL has converted its suite of single-radar severe weather detection algorithms to operate using multiple radars. NSSL has also developed a host of new radar diagnostic derivatives, including high-resolution gridded fields of vertically integrated liquid (VIL), probability of severe hail, maximum expected hail size, velocity-derived rotation, and velocity-derived divergence. Time-integrated gridded fields of some of the above have also been developed, including hail swath information (maximum size and hail damage potential) and velocity-derived rotation tracks.