Characteristics of Total Lightning within Tornadic vs. Non-tornadic QLCSs

Quasi-linear Convective Systems (QLCS) produce a variety of severe weather, including straight-line winds, hail, and occasional tornadoes. Past research has shown that a non-trivial percentage (about 20%) of all tornadoes across the United States are typically associated with QLCSs. Additionally, tornadoes spawned from QLCSs are much more difficult to accurately forecast than supercells, which can be seen from the large false alarm ratio and the small probability of detection associated with QLCS tornadoes compared to supercells.

Total lightning data and the 2-sigma lightning jump detection algorithm have been shown to be useful for identifying which storms will produce severe weather with a relatively high success rate. Furthermore, prior research has suggested that the lightning jump algorithm could potentially provide advanced indication of tornadic activity in nonsupercell thunderstorms. With the implementation of GOES-R and the Global Lightning Mapper (GLM) in the future, all NWS forecast offices will have access to high-resolution total lightning information, both spatially and temporally. This information has the potential to be quite valuable during QLCS situations.

This study analyzes the similarities and differences of total lightning behavior and the 2-sigma lightning jump detection algorithm for both tornadic and non-tornadic QLCS events. QLCS cases were selected from within the Huntsville, Alabama NWS WFO and North Alabama LMA (NALMA) from October 2007 to June 2014. The goal of this study is to explore the utility of total lightning data during QLCS events in an effort to improve NWS performance by providing an extra tool that may be used to increase situation awareness and “tip the scales” in the warning decision process.