Cloud-to-ground lightning characteristics of derecho-producing convective systems in the central and southern Great Plains

The scientific literature is voluminous with respect to the cloud-to-ground (CG) lightning and electrical characteristics of mesoscale convective systems (MCSs), particularly those that produce large hail and tornadoes. While many of these systems also produce microburst winds, only one case study has examined in detail the evolutionary trends of CG lightning in MCSs producing long-track damaging winds (i.e., derechos). Such windstorms are a tremendous hazard to people, property, and ecosystems; insured damages are comparable to those resulting from hurricanes and tornadoes and hundreds of thousands of acres of forest blow-down can have a devastating impact on the timber industry. Unfortunately, the genesis and decay of derechos and their parent convective systems continue to pose challenges to the operational meteorologist.

This study utilizes data from the National Lightning Detection Network to investigate the characteristics of CG lightning, with a focus on the total CG flash rate and percent positive CG lightning, associated with 22 warm season, derecho-producing convective systems across the central and southern Plains (mean duration >18 hours). Specifically, we determine the empirical relationships between CG flash location, polarity, storm structure, and severe wind by analyzing both the CG lightning data and the corresponding base reflectivity radar scans at six stages of event development: 1) initial convection, 2) derecho-genesis, 3) maximum derecho severity, 4) initial derecho decay, 5) final derecho decay, and 6) decaying convection. Potential nowcasting signatures in CG lightning are discussed. Time-permitting, these results will be compared to previous observations of CG lightning in severe MCSs while current hypotheses for vertical and horizontal charging structures in MCSs will be evaluated.