Lightning Decision Support Using VHF Total Lightning Mapping and NLDN Cloud-to-Ground Data in North Alabama

This study focuses on lightning safety applications at NASA's Marshall Space Flight Center in preparation for the use of new Geostationary Lightning Mapper data once operational in 2017 from GOES-16.A total of 13 years of North Alabama Lightning Mapping Array and National Lightning Detection data are analyzed for lightning safety applications.Data are analyzed using three range ring criteria used by the Marshall Space Flight Center Emergency Operations Center for monitoring and warning on lightning hazards (32-km, 16-km and 9-km).Approximately 75% of the time, the total lightning observations from the North Alabama Lightning Mapping Array provide additional lead time on the first cloud-to-ground flash, with the 25th to 75th percentile of these lead times between 0 and 23 minutes.The use of NALMA also incurs additional downtime of up to 36 minutes versus the use of cloud-to-ground data alone.Seventy-nine percent of the time that lightning is detected by the lightning mapping array in the 16-km range ring, lightning also is observed to impact Marshall Space Flight Center directly.Thirty percent (309/1043) of these events inside the 16-km range ring do not contain a cloud-to-ground flash, but continue to pose a threat to personnel and property.Thus, the threat of lightning is likely under-realized to the public because safety criteria are often based on cloud-to-ground data alone.Minor seasonal differences in lead time are observed, with the most notable difference between autumn and winter, where a Wilcoxon-Mann-Whitney independence test yield a p-value of 0.0076.