Analysis of Lightning Trends Prior to the Occurrence of Severe Weather Events

An evaluation of lightning trends prior to the occurrence of severe weather in the contiguous United States (2011-12) was performed using lightning cell tracking data from the Earth Networks Total Lightning Network (ENTLN) and National Weather Service Local Storm Reports (LSRs). Consistent one minute total lightning (in-cloud (IC) and cloud-to-ground (CG)) data are compiled thirty minutes before and after an LSR for lightning cells existing within 10, 20, and 40 km radii of a severe weather event. Many individual cases exhibit a total lightning �jump� prior to severe weather with a subsequent �drop� in lightning activity by the time of occurrence. Overall, median total lightning peaks during the 30 minutes leading up to tornado, hail, and high wind events. An approximate 15% decrease in total lightning from peak to time of event occurrence provides sample wide evidence of the �jump� and �drop� trend. Moreover, statistical evidence exists to support the observation of 15-20% higher total lightning rates within +/- 30 minutes of tornado events as compared to hail and high wind events. Using a modified version of the lightning jump detection algorithm proposed by Gatlin et al. (2010), jump detection using a 2σ approach is compared to utilizing a simple threshold approach for predicting severe weather.