Tuesday, 11 January 2005
Examination of thundersnow cases in the United States utilizing NLDN data
Cloud-to-ground lightning strikes recorded by the National Lightning Detection Network (NLDN) are used in examining case studies of thundersnow from the 2003-2004 winter season across the central United States. While oftentimes the electrical discharge will be in-cloud with cold-season, elevated convection, NLDN data could provide valuable supplemental information to the traditional surface reports in exceptional cases. In particular, more precise temporal and spatial specifications for the thunderstorm can be achieved. For this purpose, a composite plot with observations from surface stations was performed in each event archived. The thermal characteristics for the associated convection were then identified by noting whether the lightning strike occurred in temperatures above, at, or below freezing. As a result, this information helped to substantiate the true existence of thundersnow, and thus, better define the true initiation time period. Finally, the polarity of each lightning event is recorded, thereby providing information on the electrical nature of these storms.