Warm Winter Leads to Very Little Ice Cover on Lake Superior

Due to above normal temperatures over the Upper Great Lakes region for much of the winter of 2009-2010, very little ice cover exists on Lake Superior. Typically, ice cover on Lake Superior reaches its peak at the end of February and early March. This makes the current lack of ice cover even more dramatic. The satellite image below was taken on March 5, 2010. Click on the image to view a high resolution satellite photo (image is large -- just over 1mb).

Lake Superior satellite image

To see how this winter compares to historical ice cover, the following images are from the NOAA Great Lakes Ice Atlas, produced by NOAA's Great Lakes Environmental Research Laboratory. The ice atlas is based on the winters of 1973 to 2002. The first image shows the 25% point in the frequency distribution of ice cover for the March 1st through 7th time period. In other words, 25% of the winters between 1973 and 2002 had that amount of ice cover or less during March 1st through the 7th.

first quartile ice cover

 

The next image shows the median or 50% point in the frequency distribution of ice cover for the March 1st through 7th time period. In other words, between 1973 and 2002, half of the winters had more ice cover and half of the winters had less ice cover than shown in the image for the period March 1st through 7th.

median ice cover

Based on the NOAA Great Lakes Ice Atlas, it appears that in at least 75% of the winters between 1973 and 2002 Lake Superior had more ice cover than currently observed. For more information on the ice atlas, visit the NOAA Great Lakes Ice Atlas webpage.


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