A brutal chill sweeping out of the Arctic this week made the Prairies so cold that the extreme conditions even ‘tricked’ weather satellites.
All that cold air is barrelling toward the Great Lakes region this weekend—but it’s not going to punish everyone. The five lakes are actually going to protect portions of southern Ontario from experiencing the worst of the cold temperatures.
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The lakes remain remarkably ice-free for the beginning of the year. NOAA reported on Jan. 2 that the Great Lakes average ice concentration was just 1.439 percent across the entire basin. That’s significantly below the average ice coverage of about 8.8 percent expected by the turn of the new year.
All that open, relatively warm water can have a significant effect on southern Ontario’s weather.
We’re most familiar with snow squalls lashing the traditional snowbelt communities downwind of Lake Huron and Georgian Bay. These squalls form as chilly winds blow over the warmer waters below, sparking convection that gives rise to organized bands of snow.
But lake-effect snow isn’t the only way the Great Lakes influence our weather in the heart of winter.
All that warm water also moderates a blast of Arctic air before it has a chance to pour into southern Ontario. The same water that keeps the lakeshores slightly cooler during the summer can help keep the region slightly warmer in the middle of winter.
Cold winds spilling out of the Prairies have to traverse Lake Superior, Lake Michigan, and Lake Huron before they finally make landfall in southern Ontario.
Chilly air spends a long time in contact with the warm lakes before it reaches the region—significantly warming up those winds before they arrive.
This usually only benefits portions of cottage country, including Barrie, as well as the Greater Toronto Area and farther south toward London and Windsor.
Northwesterly winds pushing into northern cottage country and eastern Ontario can arrive from the Prairies without ever having touched the lakes, delivering to these areas a full shock of frigid air.