Comparing radar signatures to high-resolution hail reports

National Weather Service forecasters have several automated tools and manual techniques available for guidance in the issuance of severe weather warnings. For hail, these tools and techniques are focused exclusively on reflectivity heights with respect to the melting layer. Forecasters can also use subjective analysis of radar data to identify reflectivity structures such as three-body scatter spikes and weak-echo regions, which have been associated with severe hail. Further, past research has used Storm Data for verification; however, several studies have found deficiencies present in Storm Data. These deficiencies, such as poor spatial resolution, may have an effect on evaluating the reliability and capabilities, especially lead time, of different techniques.

The National Severe Storms Laboratory's Severe Hazards Analysis and Verification Experiment (SHAVE) provides high-resolution hail reports for thunderstorms throughout the CONUS. The high-resolution nature of SHAVE reports allow for increased confidence in identifying where severe, non-severe, and no hail fell along a storm's path. This study will use storms of varying types and severity, and from different geographical locations in the CONUS to compare reflectivity structures and heights to the high-resolution SHAVE reports. The reflectivity structures to be investigated are as follows: three-body scatter spikes, weak-echo regions and bounded weak-echo regions. Several reflectivity (18, 50, 55, 60, 65 dBZ) heights with respect to the melting level will also be investigated. This study has two major goals: 1) comparing the structures of non-severe or weak severe storms to those of severe or significant-severe storms and 2) evaluating the reliability of the structures, especially in the context of increasing lead time.