Lake effect snow machine kicks in

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Lake effect snow plumes coming ashore near Grand Rapids, Michigan.

The lake effect snow bank is open for business on the eastern shore of the Great Lakes today.

Cold air rushing in behind this week's storm is causing the snow. Lake effect snow warnings are out for parts of several states today. Muskegon, Michigan reported 7 inches on the ground early Thursday morning, and heavy snow will continue to pile up all day. In Michigan's Upper Peninsula, snowfall totals of between 17 and 32 inches are forecast by Saturday morning.

Lake effect snow is a common occurrence in early winter. Cold air rushes over the still relatively warm waters of the Great Lakes. As it does so, it draws heat and moisture from the lake water, then rings it our as snow on the leeward shores. Topography can enhance snowfall totals.

From a forecast standpoint, you generally need a temperature difference between the lake surface and 5,000 feet of about 13 degrees Celsius to create good lake effect snow. This is easy to come by early in winter when the lake waters are still relatively warm.

As winter goes on, lakes can freeze up, and shut down the lake effect snow machine alter in winter.

Lake effect greatly enhances the average annual snowfall in cities to the lee of the Great Lakes. Marquette, Michigan averages 141 inches of snow annually. Surrounding areas can pick up as much as 300 inches in a single season!

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We can be thankful we don't live on the lee side of the lakes in Minnesota. Even so, residents in northeast Minnesota are well aware that northeast winds can cause heavy lake effect snow events in Duluth and along the North Shore on occasion.

PH