GIS Analysis of Lightning Strikes within a Tornadic Environment

Recent research suggests that a maximum rate of lightning strikes occurs at least 15 to 20 minutes prior to tornado formation within a supercell storm. These maxima are associated with strengthening updrafts as they appear in radar measurements. An increase in lightning rates correlates with an increase of shear in the lower part of the storm. In combination with a strong updraft or downdraft, this shear can provide the ingredients for rotation and possibly a tornado. Polarity reversal of lightning around the time of tornado touchdown also has been examined. Thus, increasing lightning flash rates and reversal of lightning strike polarity are potential indicators of possible tornado formation. This research examines these findings by conducting a GIS analysis of tornado and lightning data from a severe storm event on 9 May 2006, which occurred near the rural town of Anna, Texas. This storm produced several tornadoes ranging from F0 to F3. The lightning data show three distinct patterns in the 50 minutes prior to the first reported tornado touchdown, which include an increase in lightning strikes, an increase in the percent of positive polarity strikes, and a spatial concentration of strikes prior to touchdown along the path of the tornado. As the study of lightning signatures becomes more refined, forecasters can use real time lightning data to compliment radar signatures in an effort to predict tornado development in severe storms