5-10+ cm of snow on tap for southern Ontario starting Sunday
Exercise caution on roads Sunday as accumulating snow pushes into much of southern Ontario
Drivers across southern Ontario should brace for slick roads and travel disruptions on Sunday as accumulating snow is in the forecast for much of the region.
A stateside system will toss moisture into cold air moving over Ontario, creating a setup where up to 20 cm of snow could fall in some areas.
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While it's still the beginning of November, so these early-season snowfalls remind residents to prepare for shifting driving conditions and ensure vehicles are winter-ready. Residents are advised to monitor any developing weather alerts and to prepare for potentially slippery roads and reduced visibility in affected areas.
Sunday: Snow dependent on storm track and temperatures
Forecasters are increasingly confident that this will be a mostly wet-snow event down to Lake Ontario’s shoreline as temperatures will hover just above freezing as the precipitation falls.
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Mixing is likely near the shoreline of Lake Ontario, limiting snowfall accumulations near the water. Lots of mixing and even a transition to rain for Lake Erie and the east end of the Niagara Peninsula as warmer air is drawn north.
The initial wave of precipitation will arrive early Sunday morning. A period of heavier and steadier snowfall should begin as the system draws closer by the late morning, continuing into the late afternoon and evening hours for many areas.
Through the event, the heaviest-hit regions in higher elevations and near the 401 and 407 could see 5-10 cm of snowfall. Any region that sees sustained, wet snow through Sunday evening has the potential to accumulate close to 10 cm of snow by Monday morning. Residents without winter tires should exercise caution.
Areas from the Greater Toronto Area (GTA) to the Niagara region are forecast to generally see less than 5 cm of snowfall, with the lowest amounts near the lakeshores.
Regions north of the GTA will naturally accumulate snowfall including areas such as Milton, Guelph, Brampton, Richmond Hill, Newmarket, all of which are likely to receive more than 5 cm of snowfall.
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As the system continues to track east, regions that transitioned to a wintry mix will have the opportunity to transition back to heavy, wet snow Sunday evening–including Hamilton and Niagara (5+ cm is possible). That part of the forecast is the least confident, and needs to be monitored carefully.
Heavy snow is forecast to move into eastern Ontario by early Sunday evening, giving some of the highest snowfall totals for the province.
A deeper supply of colder air means Ottawa's precipitation will remain as snowfall for the duration of the event, with a wintry mix through the evening and overnight near and along Highway 401 between Kingston and Cornwall.10-20 cm of snow is forecast across extreme eastern Ontario, with lesser amounts farther north and west.
It’s important to note that accumulations will be limited to grassy areas and untreated sidewalks. Temperatures close to or below 0°C Sunday morning and afternoon will support potential snow-covered or icy roads, increasing the risk of slow driving conditions.
A sharp cutoff of snowfall accumulation is expected in some regions.
Lake-effect snow chances increase early next week
Following the system, persistent Arctic air will drive multiple days of lake-effect snow in the traditional snowbelt regions on Monday and Tuesday.
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A wintry December is coming
Temperatures early next week will remain chilly, with values struggling to reach the low single digits near and south of the 401, while staying below freezing in areas well north of the 401.
A gradual temperature rebound is anticipated later in the week, with above-seasonal conditions expected as the region moves into the second half of November. However, more consistent winter weather is anticipated to settle in before the start of December, with December shaping up to feature decidedly wintry conditions.
Safety tips for driving in adverse weather
Install winter tires. Winter tires can improve stopping distance by up to 30 per cent in wintry conditions.
Prepare an emergency kit. Include the basics like snacks, first aid kit, flashlights and blankets.
Plan your travel. If possible, postpone trips during active weather and especially freezing rain. Driving is not worth the risk.
Adjust your speed. A gentle reminder that stopping distance increases exponentially as your speed increases.
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