Intense Blast of Snow on Friday Evening Could Bring Blizzard Conditions & Up to 20-30cm of Snow to Parts of Ontario
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Confidence remains high regarding a snowstorm set to impact Southern and Northeastern Ontario from late Friday into Saturday. Despite a slight reduction in the predicted snowfall totals, we're still on track for a high-impact event. This event will feature several hours of intense snowfall and strong wind gusts, which are likely to result in blizzard conditions and blowing snow.
Currently, we're anticipating a widespread snow accumulation of 15-30cm across Southern Ontario. However, areas closer to the Lake Ontario and Erie shorelines may see lower amounts, as a switch to rain is expected to limit the overall accumulation.
There's a degree of uncertainty regarding the extent of warm air intrusion, leading to discrepancies in the snowfall totals projected by different models. To account for this variance, we've opted for broader snowfall ranges instead of predicting a definitive outcome of either warm or cold air dominance.
The likelihood of warmer air influencing the weather, followed by a rapid cooldown early Saturday, introduces the risk of a flash freeze. Areas along the Lake Erie and Ontario shorelines might experience slushy conditions late Friday night due to temperatures rising to the mid-single digits and mixing with rain. This slush is expected to freeze quickly as colder air moves in behind the system, potentially leading to icy road conditions on Saturday morning.
We expect the storm's initial band of snow to hit between 4-6 PM on Friday, starting in Extreme Southwestern Ontario. This band is poised to deliver a short, intense burst of heavy snowfall, with rates of 4-8cm per hour, possibly accompanied by thundersnow.
Accompanying strong wind gusts, which could reach up to 90km/h in some localities, are expected to create hazardous driving conditions, particularly in Southwestern Ontario, the Golden Horseshoe, and parts of Central Ontario, where localized blizzard conditions may occur.
This heavy snow will progress through Southwestern Ontario, impacting London, Kitchener, and Hamilton by early evening. It will reach the Greater Toronto Area later in the evening, and eventually spread northeast to Central and Eastern Ontario, continuing overnight into early Saturday.
While the most intense snowfall will be brief, moderate snow is expected to persist behind the initial band throughout the night into Saturday. Around the Lake Ontario and Erie shorelines, a surge of warmer air Friday night into Saturday morning could result in a temporary changeover to rain, especially affecting snowfall totals in the Niagara region and parts of the Greater Toronto Area near the lakeshore.
There's increased confidence that warmer air will move in along the Lake Erie and Ontario shorelines after the intense snow band passes in the evening. This could lead to reduced snowfall totals in the Niagara region and parts of the Greater Toronto Area (GTA) near the lakeshore.
Higher-resolution models suggest that snowfall accumulation may vary significantly based on elevation. Therefore, areas like the Dundalk Highlands and along the Oak Ridges Moraine north of the GTA are likely to receive higher snowfall totals.
Steady snowfall is expected to persist throughout Southern Ontario on Saturday, with the most intense snow occurring in Eastern Ontario. The arrival of much colder air in the wake of the system will also trigger lake-effect snow squalls off Georgian Bay and Lake Huron.
These snow squall conditions are expected to continue into the next week, with the cold Arctic air remaining over our region. This could result in significant snowfall accumulations throughout the week in areas including Goderich, Kincardine, Hanover, Owen Sound, Wiarton, Barrie, Orillia, Midland, Bracebridge, Huntsville, Parry Sound, Britt, and Sundridge.
It's important to note that snowfall totals from this event will be highly variable, influenced by local factors that are difficult to precisely predict. Therefore, app-based forecasts, including ours, may vary from the forecast presented here. Our approach involves providing a broader range to account for various potential scenarios.
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We believe the hardest-hit regions will be parts of Eastern Ontario, specifically between Peterborough and Ottawa. The entrenched colder air in this area is expected to prevent any mixing, leading to significant snowfall.
The intense snow band on Friday could stall over Eastern Ontario for several hours, weakening gradually. Snowfall totals in this region are anticipated to range from 20 to 35cm, though localized areas could receive up to 40cm by the end of Saturday.
Central and Eastern Ontario, away from the Lake Ontario shoreline, are projected to receive about 15 to 25cm of snow. However, local accumulations could exceed 30cm, particularly in elevated regions through Orangeville, Shelburne, and York Region.
Areas around Georgian Bay, including Barrie, Orillia, and Muskoka, are expected to underperform in terms of snow accumulation. We're forecasting 10 to 20cm to account for this potential dry slot.
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The forecast becomes more complex further southeast into the Golden Horseshoe. Away from the shorelines of Lake Erie and Ontario, snowfall totals are likely to exceed 10cm and could approach 20cm in some areas.
Closer to the shorelines, we anticipate accumulation ranging from 5 to 15cm. This broad range accounts for the uncertainty, with areas right along the shoreline likely seeing closer to 5cm, while a few kilometres inland could receive up to 15cm.
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The tight gradient makes it challenging to represent on a map, hence the larger range. This 5 to 15cm range also applies to much of Deep Southwestern Ontario, including Windsor and Sarnia, with most of the snowfall occurring within a few hours late Friday afternoon.
The Lake Erie shoreline into the Hamilton region is expected to receive less than 10cm of snow. Meanwhile, the Niagara region might see the least amount, with less than 5cm possible.
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In Eastern Ontario, significant snowfall totals are expected to be widespread, with the 20-35cm zone southwest of Ottawa. The City of Ottawa itself is likely to see around 15 - 25cm, though totals approaching 30cm cannot be discounted.
Further southeast, the warm air will influence snowfall in the Kingston, Brockville, and Cornwall areas early Saturday morning, likely limiting totals to a general 10-20cm. However, areas right along the international border, including Cornwall and Brockville, might not even reach the 10cm mark.
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Northeastern Ontario is also set to be affected by this event, with over 20cm of snow forecasted starting late Friday evening. The heaviest band of snow is expected to move across Manitoulin Island and into the Sudbury region early Saturday morning, with snowfall rates of 3-6cm per hour.
Blowing snow and localized blizzard conditions are a concern during the morning hours across the southern portion of Northeastern Ontario, including Sudbury and North Bay. Moderate snowfall is expected to continue across Northeastern Ontario throughout Saturday, tapering off later in the evening.
The highest totals are forecasted from Manitoulin Island through Elliot Lake, Sudbury, and North Bay, with 20 to 35cm of snow possible. Locally, up to 40cm can't be ruled out, especially given the intensity of the morning snowfall.
Less snow is expected further northeast, with around 10-20cm for Sault Ste. Marie, Chapleau, and Timmins. Even lower amounts, ranging from 5 to 15cm, are possible from Wawa to Kapuskasing.
