Since the installation of the LDAR-II total (intracloud (IC) and cloud-to-ground (CG)) lightning network at Dallas-Ft. Worth, TX there have been important discoveries on how lightning behavior can unveil the dynamics and microphysics of thunderstorms. The network determines sources of electromagnetic radiation where lightning breakdown processes occur; a single flash can be composed of thousands of these sources. Total lightning mapping, along with radar and NLDN CG lightning data, can be used to diagnose the severity of a storm. The 13 October 2001 supercell event, some supercells of which were tornadic, showed lightning source heights (quartile, median, and 95th percentile heights) increased as the storms intensified. Where reflectivity cores extended upwards was where most of the total lightning occurred. The histograms of LDAR-II sources typically peaked above 10 km MSL (above the -40°C isotherm). These peaks represent the main positive charge regions of the storms. When the supercells were close to the network (within 30 km), the source density took on a classic bimodal appearance. It is speculated that the lower positive charge region is more detectable the closer the storm is to the center of the network. Flash origins most frequently occurred on the edges (either above/below) of source peaks, supporting the hypothesis that source peaks represent charge regions (flashes initiate between charge regions, where the electric field is the strongest).

LDAR-II sources were observed to surround the mesocyclone. Appendages also appeared in the source density plots, very similar to weak echo notches in radar reflectivity. Most total lightning activity occurred in regions of reflectivity gradient; it was less common for lightning density maxima to occur in reflectivity cores. During tornadogenesis, the LDAR-II and radar data indicated the updraft was weakening. The radar maximum reflectivity height and radar top (30 dBZ) started to descend 5-10 minutes (1-2 volume scans) before tornado touchdown. Total lightning and CG flash rates decreased by up to a factor of 5 to a minimum during tornado touchdown. LDAR-II source heights all showed descent by a few kilometers during this same time period. These observations agree with tornadogenesis theory that updrafts may weaken and the mesocyclone may become divided (composed of both updraft and downdraft) when a storm becomes tornadic.

One of the main purposes of this study is to show LDAR-II total lightning data can be used to diagnose storm behavior. This data has a distinct advantage over radar data in temporal resolution. If the above observations are repeatable in other storm events, using LDAR-II data in conjunction with radar data will significantly improve thunderstorm forecasting. There are some limitations with the LDAR-II data in that it is very range dependent. The number of detectable sources decreases rapidly the further a storm is from the center of the network. Grouping sources into flashes mitigates this problem somewhat, but it was still found that the number of flashes detected in a storm decreased with distance. Lightning source height information seems to be a plausible diagnostic of updraft strength, but these characteristics also have a dependence on distance from the network.