Cold Air + Warm Water = Lake-Effect Snow

February 4th, 2007 |

MODIS true color image of Great Lakes region

The coldest air of the 2006-2007 winter season (surface temperatures on 04 February 2007 were as cold as -42º F / -41º C at Embarrass, Minnesota, -31º F / -35º C at Tomahawk, Wisconsin, and -21º F / -29º C at Randville, Michigan) was flowing over the still-warm waters of the Great Lakes (water temperatures were generally +35º to +41º F / +2º to +5º C), producing widespread bands of lake-effect snow (LES) which were very apparent on MODIS true color imagery (above). Note the transition from a multiple-LES-band regime over Lakes Superior and Michigan to more of a single-LES-band regime over Lakes Erie and Ontario (below). If you look closely, you can see that ice was beginning to form along portions of the northern shore of Lake Superior, as well as along the western shore of Lake Michigan and Lake Huron. The cold temperatures were limiting snow crystal growth (creating a fine, powdery snow), but snowfall accumulations still managed to reach amounts of 17 inches / 43 cm at Grandville in lower Michigan and 12 inches / 30 cm at Rainbow Lodge in the Upper Peninsula of Michigan; farther to the east, 18 inches / 46 cm fell at Boston in western New York. The strong winds were also producing wind chill temperatures in the -30º to -40º F / -34º to -40º C range across parts of Minnesota, Iowa, and Wisconsin.

MODIS true color image of Lake Superior

MODIS true color image of Lake Michigan

MODIS true color image of Lakes Erie and Ontario