Arctic Air To Kick Off an Impactful Snow Squalls Event Between Monday and Tuesday With 15–30cm of Snow Accumulation; Locally Up to 40cm for Grey, Bruce and Simcoe Counties

The first push of frigid Arctic air will bring temperatures well below the freezing mark through Southern Ontario to start off the week. This cold air will also turn the lake effect snow machine onto full blast through parts of the snowbelt starting Monday morning and lasting through to Tuesday. Intense snow squalls with the worst conditions found during the day on Monday and overnight into early Tuesday will set up off Georgian Bay and Lake Huron in a northwesterly flow and stretch quite far inland at times. There will also be some strong wind gusts between 40-60km/h resulting in localized blowing snow and near-zero visibility out on the roads which will make travel near impossible through the affected regions.

It’s still a little uncertain on the exact placement of the snow squalls which will determine who sees the most snowfall accumulation from this event. Model data earlier in the day showed one main band off Lake Huron somewhere near Saugeen Shores and stretching as far inland as the Hwy 400 corridor south of Barrie. However, the most latest data shows a clearly northern shift in the location of the bands which would allow for some further enhancement from Georgian Bay. This would put the squall from Lake Huron over Wiarton/Owen Sound and it’ll move across Georgian Bay picking up more moisture before pushing into Simcoe County and Northern Grey County. Some additional activity. For our forecast, we’re going with the latest data, but keep in mind that we may have to make adjustments to our map if it shifts back. We will update it by the end of Sunday evening at the latest based on the evening model data.

Snow squalls and lake effect snow will develop off Lake Huron and Georgian Bay early Monday morning with a primarily westerly flow which will affect the Bruce Peninsula and into the Muskoka/Parry Sound region. This activity will be fairly weak so significant accumulation isn’t expected with maybe 5-10cm max before it shifts southward later in the morning. The lake effect snow will further intensify into a strong squall towards the late morning hours as it reaches the Northern Simcoe County region.

Now, the key thing will be if it stabilizes and stops shifting to the south locking into somewhere through Southern Bruce Peninsula, Meaford, Owen Sound, Simcoe County and areas directly east of Lake Simcoe. If it does this then we could easily see snowfall totals ranging from 20-40cm by the evening in localized pockets with general totals between 10-25cm. Heavy snowfall could be found quite far to the east as the squall will have a lot of fetch and strong winds to push it far inland. Locations such as Lindsay, Kawartha Lakes and Peterborough who traditionally don’t see a lot of lake effect snow may get up to 10-20cm along with poor driving conditions.

After the dinner hour, we expect the squall to move southward again with the enhancement off Georgian Bay being shut off and it becoming mainly fueled by Lake Huron. The fetch won’t be as intense compared to earlier in the day so the lake effect activity will be more contained to the Lake Huron shoreline. The most significant impact from this squall late Monday and into the overnight hours will be felt through the Saugeen Shores, Kincardine, Hanover, Chatsworth and Minto region where locally up to 20-40cm is possible by Tuesday morning. Some less organized lake effect snow is also possible off the southeastern shoreline of Georgian Bay early Tuesday morning with a focus on the Collingwood/Angus area potentially stretching across Hwy 400, but the Lake Huron squall will be the main event. All lake effect snow and squalls should taper off by the afternoon on Tuesday.

Please note that the accumulation map that we provided in this forecast is meant to show the maximum accumulation possible from the snow squalls. Due to the localized nature of lake effect snow, one location can get 50cm while just down the road could see less than 5cm so it’s quite hard to factor these hyper-local dynamics into the forecast. Lake effect snow is probably one of the most difficult things to forecast as just a slight change in the wind direction can shift the heaviest snow in a different direction. Even if we’re forecasting up to 40cm doesn’t mean you’re guaranteed to see it and you may see nothing at all. Just the potential is there should the environment line up. Similar to tornadoes, they don’t affect everyone within the risk zone. Sometimes the lake effect snow just doesn’t materialize to the extent that we’re expecting and sometimes they’re much stronger resulting in overachieving snowfall totals. We are continuously going over the latest update and will revise our map later Sunday evening if needed.