A mass of cold air sent a north wind over the Great Lakes region, causing large waves to form in the lakes and prompting lakeshore flood warnings and wind advisories. Lake Ontario could have 20-foot waves, CNN reports, and similar swells have been spotted in southern Lake Michigan. The waves are forecast for Thursday night and Friday, part of a winter storm bringing heavy snow to the region, then east to New England and into Canada. The coast of Maine has been warned of possible hurricane-force winds, while the wind advisories stretch as far south as South Carolina. Blizzard warnings are in effect in parts of upstate New York, where high winds and snowfall could combine to produce whiteout conditions.
The warm winter is contributing to this storm, per Forbes, by reducing ice coverage on the Great Lakes. Ice usually covers 42% of the surface at this time of year, but the lakes only have 9% coverage now, the least since 1973. The lack of ice enables more lake effect snow to form. (Read more winter storm stories.)