Posted: Dec 19, 2019 / 11:46 PM ESTUpdated: Dec 19, 2019 / 11:46 PM EST
Ice is starting to form on the Great Lakes. Great Lakes ice was at 3.7% Thursday PM. It’s a very slow process and is subject to ups and downs based on temperature and wind (strong winds break up ice, light winds (with cold temps.) encourage ice formation. Lake Huron has the highest percentage of ice cover, with the ice in Saginaw Bay and in Georgian Bay. Lake Michigan ice is starting to form in Green Bay and up toward the Mackinac Bridge.
Here’s the Great Lakes MODIS satellite picture from Thurs. PM. There was quite a bit of lake-effect cloudiness. You can see snow on the ground where it was sunny south and east of Gtand Rapids and also southwest of Chicago and in N. Ohio. You can also see there was some banding to the snowfall. There is ice in Black Bay and Nipigon Bay in Lake Superior. In Wisconsin, many of the smaller lakes are frozen over, but deeper Green Lake and Lake Geneva are open water, as are the two biggest lakes by Madison, Wisconsin (Mendota and Monona). There is also some ice formation in the Mississippi River. On 12/18/18 – one year ago – the Great Lakes had a 2.7% ice cover – so pretty similar.
Here’s a graph of maximum ice cover on the Great Lakes as a whole since 1973. It varies from 94.7% in 1979, the third of 3 cold winters back-to-back-to-back to a low of 11.9% in the mild winter of 2001-02. We’ve had above average ice extent on the Great Lakes in four of the last six winters.