A very long duration and major lake-effect snow squall event is setting up across Ontario. The snowbelts will certainly live up to their name and reputation during the next few weeks, with impressive, and possibly overwhelming, snow totals expected as we kick off December.
Road closures are certainly possible, especially over areas that receive multiple snow squall bands.
Drivers are urged to plan ahead, and be prepared to adjust to the deteriorating conditions. Travel may quickly become hazardous due to sudden changes in the weather. Snow squalls can produce intense accumulating snow or near zero visibilities.
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Several snow squalls, measuring several hundred kilometers long, will set up off of Lake Superior and Georgian Bay mid-week, as below normal temperatures settle into the region. This first round of squalls could amount to 15-25 cm in some of the harder-hit areas through Thursday.
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The powerful multi-day event starts Thursday
Even colder air, and stronger snow squalls are on the way this weekend. In fact, it will be coldest temperatures we’ve seen so far this season, helping to stir up the lake-effect snow machine.
Cold air is a key ingredient when it comes to lake-effect snow. The colder the air, the stronger the air and lake water temperature difference is, which leads to longer lasting, and more potent snow squalls.
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The multi-day lake-effect snow event will kick off late Thursday, and stick around through Sunday and beyond.
Significant snowfall will certainly impact the traditional snowbelt regions, and possibly reach into London, Guelph and parts of the Greater Toronto Area (GTA) at times.
Impacts to the GTA will depend on a localized strong squall showing up at the right place, and the right time, which we cannot rule out. There’s higher confidence in the snow forecast as you head north of Toronto. Meanwhile, areas including London, Guelph, Barrie, and sections of the 400, have multiple chances for a snow squall moving in, so it’ll be important to remain weather-aware, and be prepared for the changing conditions.
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The snowbelts are forecast to see the bulk of the snow, with over 30 cm likely through this weekend.
While there will be some lulls in the lake-effect squalls, the bands will be rather persistent and meander across the snowbelts through the first week of December, and possibly well beyond, with more impressive snow totals likely.
Great for ski areas, but trouble on the roads
This is great news for Ontario’s ski resorts, as early December will offer some of the best natural snow and snowmaking conditions we’ve seen in quite some time.
However, it does also mean trouble for the roads. Heavy localized snow with winds gusting between 40-60 km/h, will lead to whiteouts, slippery conditions, and difficult winter travel through this long duration and major lake-effect event.