Snow Cover for North America (11/29/00)
December 04, 2000
December 1 marks the first day of meteorological winter. The snow cover for North America, as shown above for November 29, is about normal for late November. Note the snows to the lee side of Lake Erie, deposited by lake effect snow storms two weeks ago. Also notice the snow free areas on the lee side of the Canadian Rockies. Areas on the downwind side of a barrier, such as the Rocky Mountains, typically receive less precipitation than areas on the windward slopes. In addition, winds moving across the Rockies warm as they move downslope. These chinook (snow-eater) or downslope winds can sublimate a considerable amount of snow in a few hours time. The yellow color represents lake ice. Lake Winnipeg has already begun to freeze, and the shallower Lake Manitoba, to the west of Lake Winnipeg, is nearly completely frozen.