Intense Snow Squalls Return to Regions East of Georgian Bay Starting Sunday Afternoon; Up to 75cm Possible for Parts of Southern Muskoka by Monday

It has been quite an active weekend throughout parts of the traditional snowbelts in Southern Ontario. Snow squalls from Friday into Saturday brought significant snowfall accumulation to the Parry Sound and Northern Muskoka region with localized reports of over 50cm in some areas. After a short reprieve early Sunday, the lake effect activity will return to the Bruce Peninsula and regions east of Georgian Bay yet again later Sunday continuing into Monday.

This time we expect one main squall to develop stretching from Tobermory across Georgian Bay and coming inland somewhere between MacTier and Port Severn. The squall will likely be more intense and focused compared to the multi-squall setup we saw on Friday and Saturday so the significant accumulation won’t be as widespread. Current data suggest a pocket along the Hwy 400 corridor including Bala and Port Carling could see over 50cm and perhaps as much as 75cm by the time the squalls move northward on Monday morning.

As of Sunday afternoon, we’re already seeing some lake effect snow off Georgian Bay and that is expected to further intensify and organize into a squall by the dinner hour. A brisk westerly to NNW wind will push the squall off Georgian Bay and into Southern Muskoka. Exactly how far this squall gets inland is unclear as some models indicate it could stay quite close to the shoreline. It should however reach far enough to cross Hwy 11 somewhere between Port Sydney and Washago. Very heavy snow along with the strong wind gusts will produce near-zero visibility making driving near impossible throughout the Muskoka Lakes, Bracebridge and Gravenhurst region. Some lake effect activity may also affect regions as far south as Midland and Coldwater. We expect the worst conditions from Sunday evening and overnight into the predawn hours on Monday. Conditions will improve later on Monday morning as the squalls weaken and lift to the north towards Parry Sound. Areas north of Parry Sound will see some more snow during the afternoon on Monday including Britt, Burk’s Falls and Sundridge but the lake effect snow isn’t expected to be that strong.

The usual disclaimer exists with this lake effect event where the accumulation can vary significantly even within just a few kilometres due to how narrow and focused these squalls are expected to be. With that being said, confidence is fairly high on the location of the band so we should be able to accurately pinpoint the hardest hit regions with some accuracy. A zone that includes the Bala and Port Carling (Western Muskoka Lakes) appears to be in the most intense portion of the squall throughout the evening and overnight hours. As a result, accumulation between 50-75cm is possible right along the Georgian Bay shoreline including the Hwy 400 corridor roughly between Port Severn and just south of Parry Sound.

Further inland, the Bracebridge and Gravenhurst area will see between 20-40cm of accumulation with locally as much as 50cm (particularly for Gravenhurst). Northern Simcoe County along with Central Muskoka and Northern Kawartha Lakes have the potential for between 10-25cm of snowfall accumulation. For the Bruce Peninsula, we’re looking at around 10-20cm for Wiarton and up to 30cm for the Northern Bruce Peninsula. All other areas around Georgian Bay will see between 5-10cm and the rest of Southern Ontario should just see a few lake effect flurries if anything at all.