Frigid Arctic Air To Kick Off Significant Multi-Day Snow Squall Event Between Sunday and Tuesday; Locally Up to 50-75cm of Snow Possible

We have seen a few snow squall events this season around Lake Huron and Georgian Bay with a few locations picking up 20-40cm this season. However, we haven’t seen a major snow squall event so far that spanned multiple days like in previous years. That is about to change with a push of cold Arctic air that will flow into Southern Ontario along with the Great Lakes that are still mostly free of ice. A brisk northwesterly wind off of Lake Huron and Georgian Bay will create the perfect environment for intense snow squalls to develop off the lakes starting Sunday afternoon.

Conditions will continue to be favourable for snow squalls through Monday and into early Tuesday which will allow for between 36-48 hours of lake effect activity. With the cold temperatures, the snow that comes down will be fluffier and drier so the moisture coming off of the lakes will go even further in creating more potential accumulation. In the strongest squalls, we could be looking at hourly snowfall accumulation ranging from 5-10cm and as a result, if a squall locks into a particular region for several hours it could add up quite fast.

We should see the lake effect snow begin to develop sometime just after the noon hours on Sunday and will likely be fairly disorganized at first as the winds will still be shifting around. Later in the day, the wind direction will become stable with a northwesterly to west-north-west flow off Lake Huron and Georgian Bay. This will allow for a fairly organized band to set up stretching over the northern tip of the Bruce Penisula, across Georgian Bay and inland somewhere between Barrie and Bracebridge. There is still some uncertainty regarding the exact wind direction and even a few degree difference can make a big difference in terms of who sees the worst conditions.

At this point, it appears the band will come inland somewhere around Midland, Washago and Orillia, but remember this may shift somewhat either to the north or south. The squall will stretch fairly far inland at times reaching as far east as Lindsay and Peterborough. The intense snow squall will continue through Sunday evening and into the early hours of Monday, but the main squall will drift slightly to the north for a few hours early Monday morning towards Southern Muskoka.

The reprieve from the snow squall for the Orillia and Midland area will be short-lived as the squall will slide back south around sunrise on Monday. It has the potential to relentlessly lock into Northern Simcoe county for much of the day on Monday and add even more accumulation on top of anything from Sunday night. Finally, we expect the wind direction to become more northwesterly which will push the squall southward towards the Collingwood and Barrie area by Monday evening.

Since it appears that the Orillia and Midland area will be the focus of this lake effect event over the next 48 hours, we’ve given them the potential for the highest accumulation. A localized pocket including Midland and areas just to the northwest of Orillia has the potential to pick up to 75cm of snow between Sunday and Monday. We have the City of Orillia along with the Northern tip of the Bruce Peninsula in the potential for up to 50cm. Southern Muskoka, the Kawartha Lakes and Barrie/Collingwood will see on and off snow squall activity over the next few days amounting to up to 25cm.

It’s important to note the ‘UP TO’ in our forecast because snow squalls are extremely hard to forecast with one location getting dumped on while down the road there is barely a snowflake on the ground. Just because you’re in the 50 or 75cm zone doesn’t mean you’re guaranteed to get anywhere close to that amount. It should be understood that somewhere within that zone will likely get that amount of snow, but that doesn’t mean it’ll be your location. Our goal is to keep you prepared for the worst as we believe it’s better to be prepared for 50cm and get 5cm instead of preparing for 5cm and getting 50cm.

For those around Lake Huron, the wind direction won’t be ideal for intense snow squalls with limited fetch off the lake except for the Bruce Penisula which will feel the brunt of the same squall affecting Simcoe County. Regardless, scattered lake effect snow over the next few days and occasional snow squalls may lead to localized totals up to 25cm by the end of Monday. This is especially true later on Monday when the squall over the Bruce Penisula drifts southward and is able to get better fetch off the lakes.

The snow squall activity will continue overnight Monday and into Tuesday, but with a more northwesterly flow. This means that a fairly intense snow squall could develop off Lake Huron and affect the Goderich, Grand Bend and London area into Tuesday morning. There could also be some lake effect snow off the southern shoreline of Georgian Bay around the Collingwood area. This isn’t included in the forecast as it’s still almost 2 days away so we will issue a forecast on Monday once we get through this round of snow squalls to ensure the best accuracy.