After one of the longest cold spells of the late 20th century, the National Weather Service declared Lake Superior frozen over on February 7, 1994. The cold of 20 years ago was even more extreme than what we have experienced so far this winter.
The freeze-over happened quickly. On the winter solstice (December 21) there wasnâ??t a bit of ice on Lake Superior. December 1993 was consistently mild through the first three weeks. On about December 20, the pattern began to shift. A big upper-level ridge of high pressure developed right along the West Coast (Image 1 above). This ridge became a more-or-less permanent feature the next seven weeks. Downstream from the ridge, cold arctic air masses repeatedly drained south out of Canada into the Upper Peninsula. In roughly 49 days the lake froze over. During this time, the National Weather Service (NWS) near Negaunee went to 20 below zero or colder nine times. Extreme cold like that is essential to ice making on the Big Lake.
Lake Superior often gets choked with ice during a typical winter, but a complete freeze over is relatively rare. In recent times, Superior was declared frozen over in 1979 and 1994 and about 90 percent ice-covered in 2003. After a relatively cold winter in 2008-09, the lake was also just about iced over in early March 2009 (Image 2).
But is the Lake really frozen from shore to shore? This was the subject of debate in the Marquette newspaper during the winter of 1912â??one of the coldest in Upper Michiganâ??s history:
Robert Blemhuber of Marquette contended that the lake was not frozen over and â??by gum, it never has been.â?? Colonel J.W. Wyckoff, of the Keweenaw, maintained it had been, and probably was now and he had proof: â??Bob Blemhuberâ?|is one of these Missouri fellows and will have to be shown I guess.â??
Wyckoff explained that he made a â??stage tripâ?? in February of 1872. He boarded the stage at Lâ??Anse and among the passengers was a party of about 20 Englishmen who had walked across Lake Superior from Canada to the Keweenaw Peninsula. They were surveying the mainland in Canada adjacent to Isle Royale when their provisions ran out. It was a familiar story: They had expected a full store of supplies by steamer, but winter came in early and the vessel was frozen in and never arrived.
The party held on as long as it could, but the situation became desperate. In February of 1872, they had no recourse but to hike out of the woods and head for â??civilization.â?? They stepped onto the ice and walked to Isle Royale, crossed it, and â??then struck across the wastes of ice on Lake Superior to Keweenaw point.â?? There were no mishaps on their roughly 70 mile journey, and they journeyed safely over the frozen lake. Wyckoff did concede that it is possible that Lake Superior was not frozen at its widest part.
That was the point Blemhuber made; the center of the lake would not freeze over. He offered the following as evidence: â??From Sauks Head Point to Granite Island [located to the north of Marquette] is a matter of twenty miles. Ever sinceâ?|a southwest wind set in, I have been able to see open water beyond the island.â??
â??I am willing to wager $1000 against a dollar that the center of Lake Superior has never been frozen over and never will be,â?? Blemhuber offered.
He went on to explain that for some miles beyond shore there is shoal and that section will freeze. â??Toward the center,â?? he contended, â??the ice absorbs the chill from the water and the result is that the center of the lakeâ??s surface is never sufficiently chilled to cause it to freeze.â?? Blemhuber concluded: â??I defy anyone to show the contrary.â??
Modern satellite technology has shown the contrary, to a point. Satellite images showed Lake Superior entirely covered with ice during the winters of 1979 and 1994. However, the ice in the center, at least in 1994, was quite thin. On February 7, 1994, an image showed the lake completely ice-covered. Then, on February 22 and 23, a storm moving through the eastern lakes caused an increase in wind from the north to northeast. The strong winds broke up the thin mid-lake ice and created open water, leading to the development of lake-effect snow. Up to eight inches of snow fell in the highlands of north-central Upper Michiganâ??at least partially vindicating the claims of Mr. Blemhuber.
This year, there is a good deal of ice on the lake, but it is not completely frozen over (Image 3). In fact, the lee shore areas (areas upwind from the prevailing west-southwest wind) show open water at present. This includes areas around Marquette. Watch what happens as the wind veers more northerly over the weekend. The ice will likely come back thicker than ever.