More Snow for Southern Ontario on Boxing Day; Intense Snow Squalls Set to Blast Parts of the Snowbelts Around Lake Huron and Georgian Bay With Locally Over 50cm of Snow by Sunday

As a system brought widespread snowfall to parts of Southern Ontario on Christmas Eve, everyone except for Eastern Ontario woke up to a White Christmas. Accumulation across the region ranged from between 10-15cm and locally higher amounts near the lakes where some of the snowbelts have received close to 30cm! Mother Nature isn’t done with us just yet though and her wintery celebrations will continue into Boxing Day with some intense snow squalls developing off Lake Huron and Georgian Bay. Current data suggests these bands will pack quite the punch with hourly snowfall rates over 5cm. Should one of the squalls stall out over a particular area for several hours it will result in very rapid snowfall accumulation. Travel will become near impossible through the snowbelts with those intense snowfall rates and near-zero visibility.

We’re already seeing some lake effect snow at this hour as of 7 PM on Friday and that is expected to give way to some more focused and intense squalls around the midnight hour. The most prolific squall will come inland from Lake Huron somewhere between Kincardine and Sauble Beach stretching all the way into the Chesley and Dundalk area. This squall will feature very extreme snowfall rates up to 6-8cm along with whiteout conditions throughout the overnight hours. A few weaker bands south of this main band could affect Goderich, Listowel and even as far east as the Kitchener area. The lake effect activity off Lake Huron will persist into Saturday although that stronger band may weaken a bit after sunrise before restrengthening later in the day and shifting around a bit.

Lake effect snow and snow squalls are also expected off Georgian Bay throughout the overnight and into Saturday. This would mainly affect Simcoe County reaching into the Kawartha Lakes region at times. It doesn’t appear that the lake effect activity off Georgian Bay will be as strong as that monster squall off Lake Huron, but it will be quite persistent and could add up over time by the time we get to Sunday. We’re also watching the potential for some lake effect snow off Lake Ontario but it won’t be the GTA and Hamilton region that sees this one. A squall currently affecting Upstate New York east of Lake Ontario may shift northward through the overnight hours and bring a few hours of heavy snow to Prince Edward County, Kingston and Brockville. It will move back stateside later in the morning on Saturday.

As is typical with lake effect snow events, the significant snowfall will be extremely localized - note this forecast is a rough idea of the potential accumulation. A slight change in the wind direction can be the difference between 5cm and 50cm for a particular area. However, based on the latest data we believe there will be two zones with the potential for over 30cm of accumulation and perhaps much more than that. This includes Bruce and Grey counties along with parts of Simcoe County like Saugeen Shores, Hanover, Chatsworth, Flesherton, Midland, Elmvale and Craighurst. Locally there could be over 50cm of snowfall accumulation in some of these areas but not everyone will see that.

In surrounding regions, we expect a general 20-30cm east of Lake Huron and southeast of Georgian Bay including Wingham, Listowel, Owen Sound, Collingwood, Barrie and Orillia. The squalls could stretch pretty far inland so the Kitchener/Waterloo and Kawartha Lake region may pick up between 10-20cm of snowfall accumulation. East of Georgian Bay through the Muskoka region and northward into Sudbury and North Bay will continue to see some moderate snowfall Friday evening and into Saturday adding up to just over 10cm.

As we mentioned, parts of Eastern Ontario may also see a few hours of heavy snowfall thanks to the Lake Ontario squall moving northward overnight. So we’ve put Prince Edward County, Kingston and Brockville in the 5-10cm zone but it wouldn’t be a surprise to see a few localized amounts near 15cm close to the international border. The GTA through the Niagara region will see the odd burst of heavy snow from the lake effect activity but less than 5cm of accumulation is expected.

All lake effect activity will come to an end early Sunday with flurries lingering throughout the day on Sunday. As we look towards the last week of 2020, we’re monitoring the potential for more lake effect activity late Monday into Tuesday and maybe another system towards the end of the week. Way too early to say for sure but we could be dealing with a fairly messy New Years’ Eve with a possible winter storm. Just an early heads up as it could change.