Total Lightning as it Relates to Rotation in Supercell Thunderstorms

Abstract:

Some of the latest work examining the capability of total lightning to provide advanced notice of severe weather has concentrated on identifying the physical links that associate it with thunderstorm processes. As a result, applications of lightning data have been evaluated in an effort to complement existing meteorological datasets in operations. The total lightning jump algorithm is one such tool, used to objectively-identify rapid increases in total lightning that signify storm intensification. In anticipation of broader coverage of total lightning afforded by the future GOES-R Geostationary Lightning Mapper, applications of lightning data in the context of particular storm environments have also been explored. The work presented here specifically analyzes total lightning trends with respect to radar-inferred mesocyclone development and strengthening in supercell thunderstorms. Supercells have long been identified as the most prolific producers of severe weather because of the dynamic and kinematic processes associated with a robust, rotating updraft. This updraft is the common physical link between lightning, the supercell’s hallmark mesocyclone, and ultimately severe weather. Specifically, the updraft is thought to tilt and stretch horizontal vorticity into the vertical to develop the mesocyclone and also participates in non-inductive charging and electrification processes. To address this conceptual relationship, this study examined total lightning and rotation in 19 diverse supercells. Results indicate that the first lightning jump signals the transition of an ordinary thunderstorm to a supercell in a supportive environment, as well as that lightning jumps often give early indication of mesocyclone strengthening. Further, it is suggested that the observed anti-correlated trend between flash rate and low-level rotation alludes to enhanced downdraft-driven vorticity generation, thought to influence tornadogenesis.