It’s the end of meteorological fall and the atmosphere is paying attention. The final days of November and the start of December will truly feel like the arrival of winter across Canada.
A setup known as ‘cross-polar flow’ will develop across Canada at the end of the month, heralding the arrival of the season’s coldest air from the Prairies to Quebec.
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Even though it’s already cold across Western Canada this weekend, things are about to get much colder as a result of this developing atmospheric pattern.
Cross-polar flow occurs when bitterly cold Arctic air over Siberia treks across the North Pole. This air can get pulled into Canada by the winds swirling around a low-pressure system.
The coldest air of the season will sweep into Northern and Western Canada by the final weekend of the month. Overnight lows may dip into the -20s and even the -30s for some. Severe cold is likely on the Prairies along with additional opportunities for snow.
It’ll take a little longer for the cold temperatures to reach Eastern Canada—but the end of our mild regime is near.
The opening days of December will see the coldest air we’ve seen so far this season. Folks across southern and eastern Ontario, as well as those along the St. Lawrence River, will struggle to hold onto above-freezing daytime temperatures. Expect subzero wind chill values for early December.
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We’re also on the lookout for the lake-effect snow machine to kick into high gear as this frigid airmass arrives across the Great Lakes.
Water temperatures across the lakes are exceptionally warm for this time of year. The sharp temperature gradient between the warm waters and the frigid air blowing overhead will create an ideal setup for lake-effect snow across the traditional snowbelt communities.
Significant bouts of lake-effect snow are possible in a setup like the one arriving soon—but it’s still too early to tell amounts or the precise locations that’ll be affected by this snowy turn of events.