Great Lakes are frozen
As of late-February, all five of the Great Lakes are “officially” frozen over. In actuality, they were about 90-percent ice covered, but when they hit that level, the people in charge of observing Great Lakes ice conditions proclaim them to be totally frozen. The last time the lakes were frozen completely was in 1994.
Few lakes completely freeze in the winter. Springs, muskrats, wildfowl, stream inflows, pressure ridges and other factors often produce areas with thin ice or even open water. In the Great Lakes, unfrozen areas can be the result of currents as in the Straights of Mackinac, St. Mary's River, Detroit River, Niagara River and a few others. There can be wind-driven openings in the ice similar to pressure ridges that occur on inland lakes.
The U.S. Coast Guard operates a fleet of ice-breaker vessels on the Great Lakes and in some areas tug boats and other vessels do ice breaker duty to keep industrial harbors in action.
The fact the lakes are frozen doesn’t make them safe for ice fishing, snowmobiling or other ice-based outdoor recreation. There are plenty of inland lakes much more safe and suitable.
There are two silver linings to the frozen Great Lakes. Winter evaporation from unfrozen surface water in mild winters is one factor creating what’s become chronic, even record low lake levels. Related to the evaporation from the unfrozen lakes is, once the lakes are frozen, the lake effect snow machine is shut down.
Michigan and the upper Midwest is getting enough snow to satisfy most people without the lake snow this winter.