Preliminary Analysis of Dual-Polarization Radar Signatures Associated with Lightning Cessation in Multicell Convection

This study seeks to better understand the timing of the last flash of lightning associated with multicellular convective events. Prior studies have developed a lightning cessation algorithm that utilizes the absence of dual-polarization radar inferred graupel and reflectivity values > 35 dBZ at the -10C level. Although the algorithm was successful in a limited test of non-severe isolated convection, it was ultimately unsuccessful at forecasting the last flash for non-isolated convection. In order to generate a more robust lightning cessation algorithm for operational use, lightning cessation and associated radar signatures in multicellular convection need to be better understood in a wider variety of common meteorological scenarios.

The Warning Decision Support System-Integrated Information (WDSS-II) software is utilized to track multicellular storms over the northern Alabama research domain. The kinematic and microphysical properties of these tracked storms are analyzed using merged WSR-88D radar data. Lightning timing, location and other properties are observed with the Northern Alabama Lightning Mapping Array in conjunction with the National Lightning Detection Network. The location of the last flash of a wide variety of multicellular convective events, whether in the convective region regardless of isolation or in the stratiform region, is then compared to radar attributes extracted from the WDSS-II software to determine if any relationships/trends can be deduced from the microphysical and kinematic properties. If a consistent set of relationships/trends with a clear physical basis can be established, then a modified lightning cessation algorithm can be developed that has wider applicability than current approaches.