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Seasonal Summary for the Great Lakes - Winter 2010- 2011

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General Overview of the 2010-2011 Season

Observed temperatures for the month of November were above normal over the Great Lakes. Temperatures cooled to below normal with the arrival of December and freeze-up in the Great Lakes happened faster than normal. The second half of December and the first part of January were much milder than normal over Lake Superior while Lake Erie remained colder than normal during that period. Much colder air moved over the Great Lakes in the second half of January but the cold weather was less severe over Lake Superior. As a result freeze-up was followed by normal to more severe than normal ice conditions except for Lake Superior. The ice coverage peaked at the end of January with December and January as a whole colder than normal for the eastern lakes and southern Lake Michigan. This was a month earlier than normal.

Generally, from early February to the end of March, temperatures ranged from above normal over Lake Superior to below normal over the eastern lakes. During that period, an intrusion of warm air over the Great Lakes around mid-February helped reduce the ice coverage to below normal values. Ice redeveloped after that but ice cover on the Great Lakes generally remained below normal for the rest of the season. Another significant cold outbreak occurred at the end of March; this was too late in the season to have a big impact on the overall ice coverage on the Great Lakes.

General ice conditions on the Great Lakes for the season, as expressed with the total accumulated ice cover (TAC), were normal.  As described earlier, there was quite a variation from lake to lake. Ice cover on Lake Superior was below normal for the season, while ice conditions on Lake Michigan, Lake Huron and Lake Ontario were near normal. Ice conditions on Lake Erie were more severe than normal.

Figures 1, 3, 5, 7, 9 and 11 illustrate the weekly evolution of the ice coverage over the entire ice season for all the lakes and each individual lake. Figures 2, 4, 6, 8, 10 and 12 show the total accumulated ice coverage (TAC) over the entire season also for all the lakes and each individual lake.

Weekly or daily ice analyses for the Great Lakes can be found at the two following URL’s:

Weekly ice coverage for all lakes
Figure 1: Weekly ice coverage for all lakes [Data]

Total accumulated ice coverage for all lakes
Figure 2: Total accumulated ice coverage for all lakes [Data]

General Overview