Multi-Day Snow Squall Event Could Dump Up to 50cm of Snow on Parts of Ontario’s Snowbelt by Monday
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After the widespread snowstorm brought blizzard conditions and even thundersnow on Friday, attention now shifts to a potential multi-day snow squall event in parts of Ontario. This event is set to start on Saturday evening and continue through Monday.
These squalls could potentially dump over 50cm of snow locally in the typical snowbelt regions around Lake Huron, Georgian Bay, and Lake Superior in the coming days. Notable accumulations are also likely through the Fort Erie and Picton area as squalls from Lake Erie and Lake Ontario occasionally cross the border throughout Sunday.
In addition to the expected significant snowfall, these squalls pose a threat of near-zero visibility, creating dangerous driving conditions in the affected areas. It's advisable to avoid the roads until conditions improve, as the lake effect snow may lead to road closures.
Snow squall activity has started off Lake Huron and Georgian Bay as of late Saturday evening. Currently, the lake effect snow is somewhat disorganized, with a thin squall stretching across the Bruce Peninsula into the Muskoka region east of Georgian Bay. Some lake effect activity is also happening south around the Kincardine and Goderich regions.
These squalls are expected to intensify overnight, with colder temperatures leading to more efficient snow accumulation. The worst conditions are anticipated in the entire Grey and Bruce counties east of Lake Huron, extending southward into Huron and Perth counties.
Over Georgian Bay, the area between Bracebridge/Port Carling and south to Orillia/Midland will be the focus. There's a chance a strong squall will establish here, though it's uncertain if it will remain stationary or drift around. If it moves, the snowfall will spread over a larger area, as opposed to localized pockets if it remains stationary.
Early Sunday morning, the Lake Erie squall, currently affecting the Buffalo region, is expected to briefly move north of the border. This will bring heavy snow for a few hours to parts of the Niagara region. The most intense snowfall rates are expected near the Lake Erie shoreline, including Port Colborne and Fort Erie.
Similarly, late Sunday morning, the Lake Ontario band is forecasted to stretch across Prince Edward County to Kingston and possibly as far north as Brockville. While only about 5-10cm of snow is expected, it will occur rapidly, accompanied by whiteout conditions. Such events often lead to crashes on the Hwy 401 corridor between Belleville and Brockville, so extreme caution is advised if travel is necessary during this time.
Both Lake Ontario and Lake Erie squalls will move back south by early afternoon as the wind direction shifts. However, the Lake Huron and Georgian Bay squall will continue to heavily impact Muskoka, Simcoe County, Kawartha Lakes, Grey County, Bruce County, Huron County, and Perth County throughout the afternoon.
Some models suggest the Lake Huron squall could stretch far inland at times with a more northwesterly flow, potentially bringing brief heavy snow to the Greater Toronto Area, Kitchener, and Guelph. Sudden reductions in visibility are possible if one of these squalls moves into your area. Areas east of Georgian Bay, including Muskoka and Parry Sound, might get a break from the snow during the afternoon as the intense bands move southward.
By evening, the wind direction is expected to shift back to a westerly direction, leading to the return of squalls in the Muskoka and Northern Simcoe County regions, as well as the Owen Sound, Kincardine, and Wiarton areas for the Lake Huron squall. Additionally, the squalls may return to the Niagara and Picton/Kingston regions after midnight, leading to more heavy snow into early Monday morning.
Our forecast only extends to Monday afternoon due to lower confidence in the exact direction of the squalls beyond that point. However, the risk will certainly continue through Monday and into Tuesday.
Current indications suggest a more southwesterly direction throughout Monday, putting the Parry Sound, Sundridge, and North Bay regions in the path of the intense squall.
The snow squall off Lake Ontario and Erie could remain stationary for many hours through the Niagara region and Kingston area, leading to potentially significant snowfall totals. More details on this will be provided in a separate forecast.
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Forecasting the exact snowfall accumulation for a specific location in a lake-effect snow event is extremely challenging. This is because of the highly localized nature of snow bands, which can lead to significant variance in totals even over short distances.
Therefore, you may notice our forecast shows significantly more snow than your weather app (including our own app). App-based forecasts often struggle with lake effect snow events due to their localized nature and reliance on data focused on larger macro-level weather events. This results in a failure to accurately capture the squalls, which operate at a micro-level, leading to intense snowfall totals.
Our forecast may still be off if the wind direction varies slightly from what the models predict, causing the snow squall band to form further north or south. That's why our forecasts use broader zones to account for this variability, meaning not everyone within these zones will see the significant totals. Essentially, we're indicating that a location within this area could see the forecasted amount.
The hardest-hit regions for the Lake Huron squall are expected to be most of Grey and Bruce counties, including Port Elgin, Hanover, Chatsworth, Owen Sound, and Wiarton. Snowfall totals here by Monday afternoon will generally range from 25 to 50cm, with some localized areas possibly exceeding this mark depending on the intensity of the squall activity.
For those east of Georgian Bay, the highest snowfall totals are likely in Southern Muskoka and Northern Simcoe County. Again, snowfall totals in locations such as Midland, Washago, Gravenhurst, Bracebridge, and Port Carling will range from 25 to 50cm, with some areas potentially exceeding 50cm.
The accumulation will quickly decrease away from the main regions, as this event is very localized. Around 15 to 30cm of snow is expected for places like Parry Sound, Haliburton, Orillia, Collingwood, Shelburne, Huron County, and Perth County. Further out, locations such as Kawartha Lakes, Wasaga Beach, Fergus, and Goderich could see 10 to 25cm of snow.
Less than 15cm is possible for the surrounding areas, with most places seeing less than 5cm. However, some areas could receive more if they encounter a brief snow squall. This includes Barrie, Kitchener, Guelph, the Greater Toronto Area, and Peterborough.
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In the Niagara region, the highest totals will be along the Lake Erie shoreline, including Fort Erie, Port Colborne, and Turkey Point, with up to 15-30cm possible. Most of this snow will fall early Sunday morning and later in the evening.
The forecasted totals will decrease rapidly the further away from Lake Erie you are. Welland could see around 10-20cm, while Niagara Falls might get 5-10cm. St. Catharines is expected to be less affected, with maybe 5cm of snow possible.
In Eastern Ontario, Picton, Napanee, and Kingston will see the most snow from Lake Ontario. The hardest-hit areas are currently projected to receive around 10-15cm, although the southernmost tip of Prince Edward County could approach 20cm.
Along the International Border into Brockville, up to 5-10cm of snow is expected from the squall moving across the area late Sunday morning.
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Intense snow squalls are also ongoing south of Lake Superior and are expected to move north of the border during Sunday afternoon. This will result in rapid snow accumulation east of Lake Superior, somewhere between Wawa and Sault Ste. Marie.
Snow squall activity in this region is expected to continue into Monday and even Tuesday. By Monday afternoon, the hardest-hit areas, including Sault Ste. Marie, will see totals ranging from 25 to 50cm. Additional snowfall late Monday into Tuesday will add to these totals.
Further east, the Chapleau and Elliot Lake regions could also experience heavy lake effect snow, with around 10-20cm of accumulation possible. The rest of Northeastern Ontario should see around 5-15cm, with lower totals further away from the lake.
