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Swath of snow, plunging temperatures, prolonged lake-effect all target Ontario

Wednesday, February 3rd 2021, 6:20 pm - A late-week burst snow, along with prolonged lake-effect conditions, will be followed by some of the coldest temperatures of the season through the weekend.

The next weather-maker for Ontario, a Colorado low, is already on its way, bringing snow overnight Thursday through Friday, with some 5-10 cm generally, but closer to 15-20 cm for lake-enhanced areas near Georgian Bay and the Dundalk Highlands. Some of that precipitation will fall as rain as temperatures briefly surge slightly above zero Friday, but a widespread blast of Arctic air beckons beyond, as fo the coldest temperatures of the season so far by next week. to the coldest air of the winter thus far for next week. For a closer look at what's to come, see below.


WEATHER HIGHLIGHTS:

  • Colorado low to bring next shot of snow to Ontario overnight Thursday through Friday
  • Snow may change to rain in the south Friday as milder air bumps temperatures
  • Shot of Arctic air will send temperatures plunging on the weekend, polar vortex to bring coldest air of the season so far next week

THURSDAY INTO FRIDAY: COLORADO LOW TO BRING WINTRY MIX, BRIEF SHOT OF MILD AIR

From its origins deep in the U.S., this brewing Colorado low will be on its way to southern Ontario Thursday, and while the northwest may see the first flakes filter in through the morning, much of the south sees clearer skies linger until the evening.

There, the snow begins in the southwest Thursday evening, ramping up through the overnight hours. The system will move at a good clip, such that much of the southwest and the GTA may actually wake up Friday to find most of its effects in the rear-view mirror, with the east experiencing it for later in the day.

21-02-03 ON Snow

Most of southern and eastern Ontario will see 5-10 cm of snow, but lower totals are expected south of the 401 corridor, where the snow will change to rain before ending, especially in the Niagara region.

A wide range in snow accumulations are anticipated for the GTA, depending on elevation and distance from Lake Ontario. Totals of 2-5 cm are possible south of the 401 and 5-10 cm north of the corridor. For much of the Dundalk Highlands and areas along the shores of Georgian Bay, however, some lake-enhancement may boost local totals as high as 20 cm over the course of the day.

Snow will then transition to rain along the 401 corridor Friday as milder air surges in, bumping temperatures to near or above freezing in most areas. However, winds will become gusty and temperatures will quickly tumble through the day as the system departs.

ONWindGust

Turning north over the Great Lakes, the storm will then head to Hudson Bay, where it will linger through the weekend.

WATCH: LAKE-EFFECT POTENTIALLY SET TO ROAR, RARE INGREDIENTS COMING TOGETHER

WEEKEND AND BEYOND: POLAR VORTEX RETURNS, EYES ON NEXT SYSTEM

Beyond the storm, the most prominent lobe of the Polar Vortex this winter is expected to migrate over central Canada for the weekend and beyond. Temperatures will then gradually drop over the Great Lakes for next week. A lack of ice on the lakes will act as a moderating mechanism for southern Ontario.

ONSatTemp

This will be a setup where Windsor will be colder than the GTA. The coldest air will detour around the Great Lakes, heading south of Lake Michigan and entering southwestern Ontario from the West. This occurs while the air targeting the GTA will be moderated by a lengthy trek over Lake Superior and Lake Huron. Look for a significant jump in ice coverage by mid-February.

Temperatures will slowly recover late-week, but remaining below seasonal.

As well, forecasters are closely watching a system that will develop along the Arctic cold front as it tracks into southern Ontario on Sunday. While the system doesn’t look impressive on computer models, it does have the potential to overachieve, as the snow will be very fluffy. Coupled with that, strong winds and plunging temperatures behind the system could produce dangerous travel with whiteout conditions.

Meanwhile, a prolonged period of lake-effect snow squalls is expected into next week, possibly continuing until next Friday, for the traditional snowbelt areas east and southeast of the Great Lakes. While the bands will meander across the snowbelts with changing wind directions, the snow totals for parts of the region will be most impressive.

Be sure to check back as we continue to update the forecast in Ontario.

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