Inland Extent of Long-Distance Lake-effect Snow Bands: Intra-seasonal Analysis and Lake Erie Case Study

Long-distance lake-effect snow (LES) bands are unique atmospheric phenomena that reach beyond the typical inland extent (IE) of LES in the Great Lakes region. They are defined by their duration (>2 hours), structural coherency, and extension beyond the regional snow belts of the Great Lakes (or > 200 km from the lake shore). Although these long-distance LES bands comprise a small portion of the total LES activity in the Great Lakes region, they have proven to be impactful with unexpected snowfall in areas outside primary LES regions. The purpose of this investigation is to understand where and how frequently these LES bands occur, the variation of their IE, and the environmental conditions that lead to their formation and maintenance.

This study utilized NCEI radar reflectivity mosaic data collected during the winters (Nov - Feb) of 2003/2004 through 2015/2016 to identify long-distance LES bands. The review of radar composites yielded 166 cases of long-distance LES bands that were divided into eight distinct categories. Intra-seasonal maximum of long-distance LES bands occurred in December and January, with lower frequencies in November and February. Their typical duration ranged from 3-7 hours, with several extreme cases lasting more than 24 hours. On average, these LES bands extended from the lake shore nearly 300 km, with some cases extending over 600 km. In addition to the climatological investigation across 13 winters, an illustrative case from 8 January 2009 was explored to gain insight into the conditions most favorable for the formation of long-distance LES bands from the eastern shore of Lake Erie. The LES band lasted approximately 6 hours and extended 713 km across New York State through the Mohawk River Valley to Manchester, NH.