Lake-Effect Cloud Band Frequency and Snowfall with Emphasis on Multiple-Lake Connections

Great Lakes lake-effect cloud bands are an indicator of thermally-generated mesoscale circulations and often produce snowfall downstream of individual or multiple lakes. An investigation of the frequency of Great Lakes lake-effect clouds during a fifteen-winter period was conducted using visible satellite imagery. Lakes Superior, Michigan, and Huron had a higher frequency of lake-effect clouds than Lakes Erie and Ontario with a climatological maximum over each lake occurring in December or January. Small-scale wind-parallel bands (WPB) generally decreased in frequency from west to east, and the frequency of larger-scale shore-parallel bands (SPB) increased from west to east.

The snowfall of lake-effect events affecting central New York state were also examined by comparing events originating over Lake Ontario to events with a multi-lake connection between Lakes Huron and Ontario. Lake-effect events and their associated snowfall accumulations were grouped according to the type of event. The results indicate that, on average, WPB events produced more snowfall than SPB events for both the single-lake and multi-lake snow bands. The single-lake WPB events produced more snowfall than multi-lake WPB events; however, single-lake SPB events produced less snowfall than multi-lake SPB bands. The likely factors leading to these interesting findings will be discussed during the conference.