A cold wind’s blowing, and it’ll reach the Great Lakes next week in true November fashion.
Above-seasonal temperatures crashed back to normal behind a cold front that swept through Ontario on Friday. This push of chilly air from the west was the first in a series of cold winds that’ll crank up the lake-effect snow machine in earnest over the next week.
Weekend clipper kicks off the snow potential
Another dose of chilly air is on the way Sunday as a clipper moves through the northern half of the province.
The first wave of Arctic air will reach Georgian Bay, developing some sporadic wet snow-showers northeast of the Greater Toronto Area (GTA) toward Georgian Bay, but no accumulation is expected.
Colorado low sets up the next lake-effect opportunities
Forecasters are monitoring the development of a Colorado low expected to move across the province on Tuesday, merging with the Alberta clipper and forming a weak trough.
While the system’s precipitation should remain mostly rain for southern Ontario, with warmer temperatures over the GTA, those around and north of Lake Simcoe have a higher chance of seeing wet snow. Fortunately, models show much less freezing rain and ice pellets across the region than we saw with the province's last messy system.
Snow will likely push across eastern Ontario, including Ottawa, through Tuesday evening.
A second dose of Arctic air sliding in behind that low-pressure system looks to bring our coldest temperatures of the season. The sharp temperature gradient between the warmer lakes and the frigid air mass pouring in will set the stage for multiple rounds of lake-effect snow squalls throughout the region.
While the snow squalls off Lakes Erie and Ontario should remain over New York, models have significant uncertainty with regard to lake-effect snow downwind of the Great Lakes. It’s all going to come down to the positioning of the Arctic air as it slides across Ontario into Wednesday and Thursday.
The highest likelihood of squalls are off Lake Superior and Georgian Bay, where localized snowfall totals of 30 cm aren’t out of the question next week. These lake-effect snow squalls could produce whiteout conditions at times.
Check back frequently this weekend and into next week as these lake-effect snow opportunities draw closer are forecasters have a clearer picture of potential accumulations and travel impacts.