The Great Lakes: a diversity of lake-effect snow mechanisms
GOES-12 visible channel imagery (above) displayed several different lake-effect snow (LES) producing mechanisms across the Great Lakes on 20 February 2008: multiple LES bands over Lake Superior, meso-vorticies over both Lake Michigan and Lake Huron, and a single LES band over Lake Ontario. Even though the Great Lakes water temperatures were getting quite cold (generally around 32-40ºF), a very cold arctic air mass (overnight minimum temperatures on 20 February were as cold as -33ºF at Grand Forks, North Dakota and Embarrass, Minnesota; -30ºF at Upson, Wisconsin; -28ºF at Stammbaugh, Michigan) was spreading across the region (GOES-12 IR image + surface reports) creating a large water-air temperature difference.
So what about Lake Erie? Since Lake Erie is the most shallow of the five Great Lakes, it often freezes the earliest; due to a large concentration of ice over that particular lake (as seen on SSEC MODIS Today true color imagery from 4 days earlier, viewed using Google Earth, below), Lake Erie was not able to contribute the necessary heat and moisture flux needed to produce LES mechanisms on the scale that the other lakes were producing on this day.
