Southern Ontario: Snow Squall Outlook for Saturday, March 12, 2022

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Forecast Discussion

Snowfall associated with the Nor’easter will continue to affect Eastern Ontario throughout the early part of Saturday. This was covered in our forecast for that system HERE. NOTE: This forecast doesn’t replace our previous map for Saturday. That remains valid as it focused solely on the system snowfall. In the wake of the system, we are looking at the brief return of lake effect snow off Lake Huron and Georgian Bay starting Saturday afternoon and lingering into the evening. The main snow squall is expected to develop off Lake Huron around the noon hour and stretch inland from Kincardine to Guelph. This band will bring localized whiteout conditions and brief bursts of heavy snow with several centimetres of snow per hour possible. The hardest-hit locations will likely include Kincardine, Hanover, Mount Forest and Wingham where up to 15cm of snow isn’t out of the question. This event will be extremely localized so not everyone in the 15cm zone will come anywhere close to that amount. It will all depend on the exact strength and placement of the squall. Strong wind gusts ranging from 40-70km/h will accompany the snow squall activity so blowing snow and near-zero visibility out on the roads will be a concern. Avoid travel through the affected regions if you can. Highway closures in Grey-Bruce counties are likely during the day on Saturday.

By the late afternoon or early evening, the squall may briefly reach into parts of the Western GTA including Hamilton, Burlington and Grimsby along with K/W and Guelph. Local accumulation here may approach 10cm if it lasts more than a few hours. However, it’s questionable so we didn’t include them in the up to 15cm zone. In addition to this, we could also see some unorganized lake effect snow off the southeastern shoreline of Georgian Bay. The issue is that Georgian Bay is partially frozen which will significantly limit the potential for any lake effect activity to get organized. So any activity will be contained close to the shoreline including Collingwood and Wasaga Beach. Again, locally up to 10cm can’t be ruled out around Georgian Bay but most locations will see less than 5cm. All lake effect snow should taper off just after midnight ahead of a weak system on Sunday that could bring another few centimetres of snow to Southern Ontario.

Southern Ontario: Snowfall Outlook for Friday, March 11 - Saturday, March 12, 2022

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Forecast Discussion

The week will come to an end on a snowy note across Sothern Ontario as widespread light to moderate snow moves through the region starting Friday morning. This push of moisture in advance of a strong Nor’easter expected to track up the American Northeastern this weekend bringing heavy snow to parts of Upstate New York and New England. While earlier indications suggested it could have an impact on the Niagara region and Eastern Ontario, it now appears that the bulk of the moisture will stay well south of the border.

We will still see accumulating snowfall for those northwestern on the GTA including the Hanover, Orangeville, Newmarket and K/W region early Friday morning. This first wave of snowfall will continue throughout the morning before dissipating by the early afternoon. We expect to see around 4-8cm of snowfall accumulation in the aforementioned regions by the end of Friday. Those in Southwestern Ontario along with the GTA and around Georgian Bay can expect a few centimetres of fresh snow with ~5cm at most in the hardest-hit locations.

Another round of snow is expected to develop over the Niagara region and stretch into Eastern Ontario late Friday afternoon into the evening. This could also affect the GTA during the evening rush hour so do expect some impact on travel. Snowfall will continue to persist overnight and into Saturday morning before moving out as the Nor’easter misses us to the south. We expect the second wave will have a bit more moisture to work with so snowfall totals for Eastern Ontario and parts of the Niagara region will range from 6-12cm by Saturday morning. Can’t rule out that a few locations mainly through Kingston, Brockville and Cornwall approach the 15cm mark depending on how close the Nor’easter tracks to the border.

As the system moves out of the province, colder air will flood in behind it pushing temperatures well below the freezing mark on Saturday. There are some models suggesting that we could see the return of snow squalls off Lake Huron which could bring additional snowfall accumulation to parts of Grey-Bruce late Saturday. However, there is reason to be skeptical given this is a new trend in the models and how late we are in the season. Generally, we don’t see significant lake effect snow this late as the lakes are usually mostly frozen by now. That’s the case for the majority of Georgian Bay, but there is still a segment of Lake Huron that remains free of ice. But the ice that is present could inhibit any lake effect snow from getting too organized. As such, the forecast map above doesn’t factor in any accumulation from the lake effect activity. We will continue to monitor the latest data and post a forecast for the squalls as we get closer to Saturday.