Lake Effect Lightning Climatology of the Great Lakes

Ted Letcher and Scott Steiger
State University of New York
Oswego, New York

ABSTRACT

     Lake-effect storms form over the Great Lakes region every year during the fall and winter months, when cold air crosses over the relatively warm lakes. Occasionally, these storms are capable of producing lightning. Lake-effect thunderstorms are important to study because they produce lightning in shallow convective clouds compared to the traditional summertime thunderstorms. Also, lake-effect thunderstorms can be associated with thundersnow. A climatology of lake-effect thunderstorms was constructed for each Great Lake in order to find any seasonal patterns. In order to determine the number of lake-effect thunderstorm events that occurred during the 12- year period from 1995-2007, radar and sounding data were analyzed for lake-effect parameters identified in previous research, and then compared to lightning flash density plots using National Lightning Detection Network (NLDN) data across the Great Lakes region. A total of 31 separate lake-effect thunderstorm events were found over the upper Great Lakes, adding to the 70 events previously found over the lower Great Lakes. The lower Great Lakes produced the highest number of thundersnow events. The majority of lake-effect thunderstorms that occurred across the upper Great Lakes was early-season rain or mixed precipitation events. Several inhibiting factors for lake-effect thunderstorms were noted to be responsible for the relative dearth of lake-effect lightning across the upper Great Lakes (Superior, Huron, Michigan). The predominant factors included lake surface temperature, shape and geographic location. It was also found during the study that enhancement from upstream lakes is tied to lake-effect thunderstorm development. The most evident lake-effect thunderstorm enhancement occurred from Lake Huron to Lake Erie in what has been defined by this paper to be a Lake Huron-to-Erie Connection (LHEC). The results of this study will aid forecasters to better predict lake-effect thunderstorms as well as provide an opportunity for more in-depth research on lightning in shallow convective clouds.



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