The Arctic air spilling into parts of Western and Central Canada is not a trick and will be no treat. The lake-effect snow machine will be shaking off the dust in a wide area as we enter November -- from Manitoba to Lake Ontario -- reaching more than 1,500 km. The extent of the lake-effect bands is due to the Arctic air filling an upper trough, which stretches from Saskatchewan to Quebec, combined with water temperatures in excess of 10°C in most places. For details on this week's wintry framework, read below.
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THIS WEEK: LAKE-EFFECT SNOW COVERS TWO PROVINCES
An interesting setup is at play: A ridge over Alberta has joined forces with a broad upper-level trough over Eastern Canada to funnel Arctic air into Manitoba and northern Ontario.
Temperatures of -10°C to -15°C at roughly two kilometres altitude is drawing ample moisture from the relatively warm waters of central Manitoba and northern Ontario.
On Sunday, north-northwesterly winds will drive lake-effect squalls into the Winnipeg region and intermittently impact the Trans-Canada Highway from Portage La Prairie, Man., to the Ontario border, along with Highway 11 and 17 in Ontario from Lake of the Woods to Lake Superior.
Snow will continue into Monday for Manitoba and northwestern Ontario before the wind shifts, while the prime conditions change over the Great Lakes.
The eastern shores of Lake Superior will see mixing along Highway 17, while the heaviest snow will be confined to higher elevations away from the lake.
Most areas will just see a cm or two but the southeastern shores of lakes Winnipeg, Manitoba, Seul, Nipigon and Lake of the Woods could see 5-10 cm locally. The bands of snow will linger through Monday.
The same Arctic air will then trickle south into the central Ontario Monday overnight, with lake-effect showers beginning to transition to snow primarily east of Muskoka, as well as the Dundalk Highlands.
In addition to the snow, winds will also be breezy, particularly in the aforementioned regions, with gusts of 40-60 km/h expected Monday afternoon and evening.
This pattern looks to lock in over the Great Lakes for the first week of November, keeping temperatures below seasonal, as well as keeping significant systems at bay.
"Associated with this is a pool of Arctic air. We have all that heavy rain in Eastern Canada, [which will] be moving north. This cold air is going to be replacing it," says Kevin MacKay, a meteorologist at The Weather Network.
For the traditional snowbelt areas east and southeast of the Great Lakes, the first measurable snowfall of the season is expected with the more persistent bands, especially across the higher terrain mid- and late this week.
Stay tuned to The Weather Network as we monitor the forecast in Manitoba and Ontario this week.