Monday, 5 November 2012
Symphony III and Foyer (Loews Vanderbilt Hotel)
This study integrates past research methodologies along with the National Lightning Detection Network (NLDN) remote sensing dataset to analyze the lightning and severe weather hazard relationship for the 27-28 April 2011 Southeast U.S. tornado outbreak. Lightning data from the NLDN are utilized to examine the lightning characteristics associated with seven supercell thunderstorms that produced significant and/or violent tornadoes. Results illustrate that the majority of the seven supercells experienced a local maximum in total cloud-to-ground lightning flash rate prior to tornadogenesis followed by a local minimum in total cloud-to-ground lightning flash rate that was coincident with tornadogenesis. Moreover, the majority of the seven supercells within this study experienced an increase in total cloud-to-ground lightning flash rate following tornado dissipation. It is surmised that this distinctive lightning frequency pattern found during tornadogenesis (tornadolysis) is due to updraft intensification (weakening). Findings also demonstrate that all seven supercells within this study were dominated by negative polarity cloud-to-ground lightning flashes, which is expected due to the time of year and location of the severe weather event occurrence (i.e., early spring and southeastern U.S.). Further, this study examines total lightning flash rate and low-level mesocyclone intensity relationship. It was found that the low-level mesocyclone and total NLDN flash rate relationship results were varied and inconsistent among the storms examined. Thus, it is deduced that the intensification or weakening of the low-level mesocyclone is one of many dynamical processes that influence a supercell's internal charge structure that ultimately affect the overall lightning production within the storm. Overall, results from this analysis corroborate prior research, which suggests that lightning attributes and their patterns can yield insight into internal storm dynamics and hazard production.
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