Overnight on March 2-3, 2020, several severe thunderstorms affected parts of Missouri, Arkansas, Kentucky, and Tennessee, with the most notable damage occurring around the Nashville metropolitan area. At the time of this blog post, storm surveys continue in Tennessee by National Weather Forecast Offices in Nashville and Memphis TN (https://www.weather.gov/ohx/ , https://www.weather.gov/meg/). This post takes a preliminary look at the electrical characteristics of the thunderstorms responsible for this damage from the lens of the newer instruments on the GOES-R series of satellites, the Geostationary Lightning Mapper (GLM). GLM measures optical lightning signatures in thunderstorms to determine the spatial extent and frequency of lightning as it propagates through the cloud.
Figure 1 shows an animation of flash extent density within the NWS primary warning dissemination tool, AWIPS2 between 0445 UTC and 0835 UTC. Note that there are 3-4 distinct pulses in lightning activity as the storm traverses Central Tennessee. If we look at a time series of this flash data, there are five distinct rapid increases in the flash rate, known as lightning jumps, were observed (0445 UTC, 0509 UTC, 0545 UTC, 0730 UTC, and 0802 UTC; below, Fig. 2). Rapid increases in flash rate depicted in Figure 2 are associated to strengthening updrafts in the mid-levels of thunderstorms, where the strengthening updraft facilitates charge separation and an increase in the lightning frequency.