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

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.