92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Wednesday, 25 January 2012
Utilizing Lightning Detection for Advanced Storm Warning: Case Studies From the Spring 2011 Tornado Outbreak
Hall E (New Orleans Convention Center )
Mark Hoekzema, Earth Networks, Germantown, MD

The historic tornado outbreak in late April 2011 produced over 300 confirmed twisters and 322 fatalities across the Deep South is one of the worst tornadic events in U.S. history. This catastrophic event was analyzed to emphasize the value of the advanced warning provided by the Earth Networks Dangerous Thunderstorm Alert program. In a subset of 8 damaging tornadoes, the Dangerous Thunderstorm Alerts (DTAs) were issued as much as 21 minutes prior to the onset of severe weather, such as large hail, damaging winds, heavy rainfall, and tornadoes. The average advanced warning time provided by the DTAs in these 8 events was 13 minutes. Recent advances in lightning detection technology developed by Earth Networks has proven that in-cloud (IC) lightning is better correlated to storm severity than cloud-to-ground (CG) lightning, providing early indicators of the development of severe thunderstorms that produce damaging hail, heavy rainfall, high wind or tornadoes. The detection of total lightning flashes, especially the IC flashes, enables improvement in the lead time of severe weather prediction and alerting. The Earth Networks Total Lightning Network (WTLN) detects both IC and CG flashes efficiently.

The properties of lightning cells preceding numerous severe storms have been studied and certain predictive patterns in the lightning cells have been identified. The time evolution of the lightning flash rate and the IC/CG ratio of individual cells are used to identify severe thunderstorms with significant lead time before they occur. The sudden rise of the rate of IC discharges and subsequent peak of total flash rate can serve as an indicator for severe storm conditions. Earth Networks has utilized data from its Total Lightning Network to develop real-time lightning cell tracking and the Dangerous Thunderstorm Alert program which provides alerting with lead times of up to 30 minutes prior to severe storm impact.

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