Southern Ontario: Snowfall Outlook for Thursday, December 23, 2021

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Forecast Discussion

A fast-moving system is expected to bring a blast of snow to areas east of Lake Huron and into the GTA beginning Thursday late afternoon. It will continue throughout the evening hour with the snow tapering off just after midnight. In addition to this, the Sarnia and Chatham-Kent region could see some brief freezing rain just in time for the Thursday evening commute. Windsor should mainly see rain from this system. As for accumulation, this will be a fairly weak system in terms of moisture content so we expect around 2-6cm (locally as much as 10cm, but that seems unlikely) from the Lake Huron shoreline through K/W and into the GTA. Lower totals may be found along the shoreline of Lake Ontario as temperatures will be very close to the freezing mark. For those hoping for a White Christmas, we don’t expect the snow to stick around until Christmas with a warm-up on Christmas Eve and rain expected.

Northern Ontario: Snowfall Outlook for Tuesday, December 21 to Wednesday, December 22, 2021

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Forecast Discussion

Accumulating snowfall is expected across Northeastern Ontario late Tuesday continuing into Wednesday. Total accumulation from this system will generally range between 6-12cm with lower amounts further to the northwest. A few locations particularly east of Lake Superior and north of Georgian Bay could pick up as much as 15-20cm by the end of Wednesday due to some lake enhancement. There is also a zone including Timmins, Cochrane and Englehart that has shown up in multiple different weather models with the potential for accumulation reaching 15-20cm as well. The snow will come to an end by mid-day Wednesday.

Southern Ontario: Snowfall Outlook for Tuesday, December 21 to Wednesday, December 22, 2021

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Forecast Discussion

A weak system will move into northern parts of Southern Ontario late Tuesday evening bringing the potential for some light to moderate snowfall continuing into Wednesday. This will mainly affect Northeastern Ontario and into some parts of Central Ontario to the northeast of Georgian Bay. Total snowfall accumulation will generally range from 6-12cm, but a few locations along the northern shoreline of Georgian Bay could see up to 15-20cm due to lake enhancement helping to boost totals. The system will move out by Wednesday afternoon, however, lake effect snow is expected to develop off Lake Huron and Georgian Bay in the wake of the system.

Current indications suggest one main squall will set up off Lake Huron affecting the northern Grey and Bruce counties throughout the afternoon and into the evening. A few locations may approach 15-20cm by the end of Wednesday due to these squalls with more general amounts ranging from 5-10cm. For Georgian Bay, some heavier lake effect snow could result in accumulation between 6-12cm and locally up to 16cm in parts of Simcoe County.

The lake effect snow may linger into Thursday, but there is low confidence on intensity and location so that will be covered in a future forecast.

Northern Ontario: Snowfall Outlook for Sunday, December 19, 2021

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Forecast Discussion

A system will slide into Northwestern Ontario from Northern Manitoba during the afternoon on Sunday. This will bring the potential for accumulating snow for those near the Manitoba border and into Far Northern Ontario. Total accumulation of around 6-12cm is possible with localized pockets picking up to 15cm by the end of Sunday. Lake enhancement around the northern shoreline of Lake Superior may also boost totals into the 6-12cm range. The snow will continue into early Monday with the chance of up to 5-10cm of accumulation along the Quebec border and up into Moosonee. It will fully clear out by Monday afternoon as the system moves out over Quebec. Blowing snow may also be an issue at times with wind gusts reaching 20-40km/h late Sunday and continuing overnight.

Southern Ontario: Snowfall Outlook for Saturday, December 18, 2021

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Forecast Discussion

A system is expected to slide across the Lower Great Lake on Saturday and bring accumulating snowfall to parts of Southern Ontario. Precipitation will start to move into our region from the west during the mid to late morning hours with snowfall spreading eastward throughout the late morning. Eastern Ontario should see the first flakes sometime around the lunch hour and will further intensify later in the day. This steady snowfall will continue throughout the afternoon and into the early evening before clearing from west to east. We expect the bulk of the snow to be finished by midnight although flurries may continue to linger around into the overnight hours, especially for Eastern Ontario. Closer to Lake Erie and into Deep Southwestern Ontario, it will be just warm enough to allow for some rain to mix in with the snow which would reduce accumulation.

We’re looking at widespread snowfall totals ranging from 6-12cm from Sarnia to London through the GTA and into much of Eastern Ontario. There is the potential for a few areas to approach 15cm, especially over the higher elevations of the Dundalk Highlands and along the Internation border in Eastern Ontario. Lower amounts for regions east Georgian Bay where less moisture will be present along with the Lake Erie shoreline due to the mixed precipitation. Blowing snow could be an issue around Lake Ontario where wind gusts may reach 30-50km/h during the day on Saturday.