Wednesday, 14 August 2002: 4:45 PM
Preliminary results from the North Alabama Lightning Mapping Array
Several severe weather episodes have been documented using the recently
commissioned North Alabama Lightning Mapping Array. The array consists of
12 sensors capable of detecting and locating VHF radiation sources from
lightning flashes in storms. Both intracloud and cloud-to-ground lightning
are detected by the system. Good coverage is available out to a range of
200 km from the network centroid, which is located in the vicinity of
Huntsville, Alabama.
Results from the large tornado outbreak of 24 November 2001 and other recent storm events will be presented. Data from the 24 November 2001 event reveal relatively modest flash rates from the series of supercell storms that spawned the 24 documented tornadoes in Alabama. The ratio of IC to CG flash rates was also highly variable from storm to storm. The frequency of occurrence of total flash rate changes prior to and during tornadoes is examined, as well as the occurrence or non-occurrence of lightning holes within the strongest updrafts.
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