0% to 0.09% Grey
0.1% to 0.99% Light Blue
1% to 10% Darker Blue
10.1% to 25% Brighter Blue
25.1% to 50% Light Purple
50.1% o 75% Bright Purple
75.1% to 99% White
I posted each month separately because the original image was too big...too long.
Top row is 1972-73. Bottom row is 2018-19
Per Great Lakes Environmental Research Laboratory (GLERL) "From 1973 through 1988, the source was the Canadian Ice Service. Beginning with 1989, the source was the U.S. National Ice Center, (NIC). Data from both Canadian and U.S. sources is combined in NIC's daily products."
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| NOVEMBER |
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| DECEMBER |
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| JANUARY |
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| FEBRUARY |
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| MARCH |
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| APRIL |
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| MAY |
