Lake effect snow is slamming the Great Lakes, with seven states from Wisconsin to New York under snow alerts on Monday.

In late fall and winter, lake-effect snow is a common occurrence in the Great Lakes region. "Lake-effect snow occurs when cold air, often originating from Canada, moves across the open waters of the Great Lakes.

Lake-effect snow blowing in from the Great Lakes has blanketed parts of Michigan, Ohio, Pennsylvania and New York, stranding hundreds of vehicles on roads and snarling post-Thanksgiving travel. Well over two feet of snow had fallen in many parts of the region by early Monday,