An analysis of thunderstorm hail fall patterns in the Severe Hail Verification Experiment

During the summer of 2006, the National Severe Storms Laboratory conducted the Severe Hail Verification Experiment (SHAVE). One purpose of SHAVE is to assist in the verification of multi-sensor, multi-radar hail diagnosis grids that have a spatial resolution of approximately 1 km by 1 km; thus, hail reports at a much higher resolution than what are currently available from sources such as Storm Data are needed to verify the grids. SHAVE uses Geographic Information Systems (GIS) to combine hail grids and other radar data with geospatial information to provide guidance to a team of University of Oklahoma meteorology students making hail verification phone calls to the public. Ideally, call locations are within approximately 2 km of each other in areas that have been affected by thunderstorms. Strategies used for sampling different storm types are discussed and illustrated, and example storms producing golf ball-sized (44.45 mm) and larger hail are analyzed. Storm evolution, the near-storm environment and the multi-sensor, multi-radar hail diagnosis grids are compared for several cases.