An Analysis of Total Lightning Over North Alabama During the 2 March 2012 Tornado Event

The 2 March 2012 tornado outbreak is best-known for the strong tornadoes which impacted portions of the Ohio Valley. However, the event kicked off far to the south, over northern Alabama, where a long-track EF-3 and shorter EF-2 tornado occurred in rapid succession over Madison and Limestone counties. Additional weaker tornadoes were observed later in the afternoon as the severe weather event transitioned from primarily a tornado threat, to primarily a damaging wind and hail threat.

The north Alabama portion of the 2 March 2012 event occurred within the domain of the North Alabama Lightning Mapping Array (NALMA), a very high frequency (VHF) detection network consisting of 11 sensors spread across north central Alabama and two sensors located in the Atlanta, Georgia region. The primary advantage of this network is that it detects total lightning, or the combination of both cloud-to-ground and intra-cloud lightning, instead of cloud-to-ground lightning alone. Total lightning information is directly linked to storm updraft strength, as the updraft is responsible for charging mechanisms within the storm. To that end, NALMA data have been available to National Weather Service offices in and around the network for operational use since 2003. The total lightning data can increase a forecaster's confidence to either issue or not issue a warning since the NALMA data provide additional insight into the storm's evolution between radar volume scans.

This presentation will analyze NALMA data from the 2 March 2012 event in two ways. First, operational use of the data to anticipate the first round of severe thunderstorms will be discussed, particularly in the context of its use as a decision-support tool for operational forecasters. Second, total lightning data for all of the 2 March tornadoes within the domain will be presented, including a brief discussion of the total lightning trends during the life cycle of the long-track EF-3 tornado.