Alberta Clipper to Bring a Snowy Blast to Southern Ontario on Wednesday With Up to 20cm Possible; Snowbelt Region Could See Up to 50cm
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The snowy landscape across Southern Ontario is quickly transforming as a multi-day snow squall event has blanketed parts of the snowbelt regions with over 100 cm of snow.
While the intense accumulation has primarily impacted areas around Lake Huron and Georgian Bay, the rest of Southern Ontario will soon have their turn as a weather system moves into the region on Wednesday.
This system-related snowfall will likely combine with lake enhancement and embedded snow squalls, resulting in higher accumulations in the snowbelt areas that are still digging out from the weekend’s relentless snowfall.
By Thursday morning, some snowbelt regions could see an additional 30-50 cm of snow. Meanwhile, a general 5-15 cm of snow is expected across much of Southern Ontario, including parts of the Greater Toronto Area (GTA), which has experienced minimal snowfall so far this season.
The Alberta clipper responsible for this system began pushing into Northwestern Ontario from Manitoba on Tuesday afternoon. Moderate to heavy snow will continue spreading across Northern Ontario through the evening and overnight.
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In Northern Ontario, we expected the highest snowfall totals to be found east of Lake Superior stretching from Wawa down to Sault Ste. Marie. Snowfall totals of between 30 to 50cm are possible thanks to the system-related snowfall and snow squalls off Lake Superior.
Other areas around the Georgian Bay shoreline extending into Sudbury could be looking at around 20cm of snowfall accumulation. This will also be the case south of Lake Nipigon which could see some lake enhancement between Thunder Bay and Geardton.
The rest of Northeastern Ontario is looking at around 10 to 15cm with locally up to 20cm. Less than 10cm is expected for Northwestern Ontario including Thunder Bay.
PRECIPITATION TYPE - MAP FROM WEATHERBELL
Ahead of the system, lake effect snow has already started to intensify, beginning with Lake Superior on Tuesday afternoon. By Tuesday evening, snow squalls are expected to organize off Lake Huron and Georgian Bay, primarily targeting the Bruce Peninsula and areas northeast of Georgian Bay, such as Parry Sound, Britt, and North Bay. These snow squalls are likely to persist through the night into Wednesday morning.
Additional lake effect snow could develop off Lake Erie and Lake Ontario during the early morning hours of Wednesday, potentially drifting into the southern Niagara region and Prince Edward County. While this activity may cause reduced visibility and locally heavy snowfall, the squalls are not expected to remain stationary for long, limiting overall accumulation.
PRECIPITATION TYPE - MAP FROM WEATHERBELL
As the system reaches Southern Ontario around sunrise on Wednesday, the existing lake effect snow bands are expected to merge with the system’s light to moderate snowfall. This merging could enhance snow totals, particularly off the northern shorelines of Lake Erie and Lake Ontario. Narrow bands of heavy snow could stretch across the Niagara region and into parts of Central and Eastern Ontario, leading to significant variations in snowfall accumulations.
Snow totals will likely vary substantially due to localized banding caused by lake enhancement. Some areas may see only 5 cm, while nearby locations could receive 15-20 cm, depending on where the snow bands develop.
Another key factor with this system will be strong wind gusts, ranging from 50-70 km/h across Southern Ontario, beginning Wednesday morning and continuing throughout the day. These winds, combined with steady snowfall, could create blowing snow and reduced visibility, making travel hazardous. With this being the first significant snowfall event of the season outside the snowbelt, drivers are urged to exercise caution.
PRECIPITATION TYPE - MAP FROM WEATHERBELL
While the system is expected to exit Southern Ontario by late Wednesday, snow squall activity will persist off Lake Huron and Georgian Bay. An intense squall is projected to develop off Georgian Bay late Wednesday evening, stretching inland toward Midland, Orillia, and Gravenhurst, and continuing into the early hours of Thursday.
PRECIPITATION TYPE - MAP FROM WEATHERBELL
By Thursday morning, shifting winds will push the Georgian Bay squall southward toward Collingwood and Angus. This squall may extend far inland at times, impacting the Highway 400 corridor between Vaughan and Barrie, as well as parts of the northern GTA. Meanwhile, a Lake Huron squall is anticipated to stretch from Goderich through Grand Bend and into the London area.
Significant snowfall could occur on Thursday if these squalls remain stationary for an extended period. Current models suggest they may not weaken until late Thursday night or early Friday morning, potentially producing intense snowfall rates for over 24 hours.
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Regarding snowfall totals, the uneven distribution caused by lake enhancement means localized accumulations will vary widely. The highest confidence lies in regions northeast of Georgian Bay, including Parry Sound, Sundridge, Britt, and North Bay, where 30-50 cm of snow is expected, with localized amounts possibly exceeding those totals due to snow squalls.
Surrounding areas, such as Muskoka and Orillia, could see 20-30 cm of snow by Thursday morning, accounting for system snow, lake enhancement, and snow squall activity. Similarly, areas east of Lake Huron could see totals ranging from 20-30 cm.
In Central and Eastern Ontario, widespread snowfall is likely to range from 10-15 cm, except for the Ottawa Valley, where accumulations may be closer to 5 cm. Lake enhancement could push some areas along the northern shorelines of Lake Ontario and Prince Edward County closer to 20 cm.
For regions such as Kitchener, Woodstock, Guelph, and Barrie, snowfall totals are projected to reach 10-15 cm. However, variability due to lake enhancement may result in some areas seeing lower amounts. The GTA is expected to receive closer to 5 cm, while the Niagara region could accumulate 5-10 cm, with localized heavier bands of snow influenced by Lake Erie.
In Deep Southwestern Ontario, snowfall amounts will decrease westward, with London forecasted to receive around 10 cm. Further southwest, including Sarnia, Windsor, and Chatham, totals are expected to remain under 5 cm.
It’s important to note that these totals do not account for the snow squalls expected to impact areas southeast of Lake Huron and Georgian Bay beginning Thursday morning. High-resolution models are still refining the locations of these squalls, but additional accumulations of 30-50 cm are possible in affected areas. Stay tuned for a detailed update in a separate forecast.
