Powerful winter storm walloping Ontario, 50+ cm expected
A significant Great Lakes winter storm will bring hazardous conditions to northern Ontario through Monday. Freezing rain, up to a half a metre of snow and zero visibility will make travel nearly impossible, with road closures likely
A major winter storm is bringing heavy snow to northern Ontario, with blizzard conditions for areas along the Trans-Canada Highway.
With a potential of 30-50+ cm of snow, coupled with wind gusts between 50–90+ km/h, travel will likely be treacherous, if not impossible, through Monday.
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Highways 11, 17, 101, 129, 144 and 631 will be particularly impacted. Avoid non-essential travel and outdoor activities. Road closures are possible. Prolonged utility outages are likely.
Be sure to check back for the latest forecast updates as this system develops, and keep an eye on the road conditions before heading out.
Major winter storm continues into Monday
A deep Arctic air supply across the eastern Prairies, paired with exceptionally mild air across the southern U.S., will provide the perfect environment to rapidly develop a low-pressure system throughout Sunday.

The Colorado low will have a noteworthy low-pressure, likely near 980 hPa by Monday. That means most of Ontario can expect a threat of strong-to-potentially damaging winds.
A more persistent round of ice will slide through the Nickel belt overnight into Monday.

Highway 17 will increasingly become more dangerous as steady snow settles into the region, and travel on this route isn't advised from Sunday evening through Monday.
By Sunday evening, snowfall rates of 3 to 5 cm an hour will be possible near Sault Ste. Marie, with blowing snow and localized whiteout conditions.

Monday: Snow continues in the north
As temperatures begin to climb in southern Ontario on Sunday night, conditions continue to worsen in northeastern Ontario.
After midnight, a wintry mix develops as you approach Elliot Lake (freezing rain, ice pellets), creating unique hazards and slick conditions--limiting snowfall accumulations for Sudbury and the North Bay regions.

Wind gusts reach up to 100 km/h along the Lake Superior shoreline.
T40-50+cm is forecast in the hardest-hit regions, in communities east of Lake Superior, including Sault Ste. Marie, Chapleau, Timmins, Kirkland Lake, New Liskeard, Elliott Lake, and Sudbury. Surrounding areas like Kapuskasing and Sudbury could see 30+ cm.
Highways 11, 17, 101, 129, 144 and 631 are expected to see hazardous travel conditions throughout much of Monday. Road and highway closures are near certain.

Conditions decline near Timmins, and the heaviest snowfall pivots across the community with widespread blowing and drifting snow.
Blizzard conditions are forecast near Lake Superior, from Wawa to Sault, as sustained, northerly winds peak to 40-60 km/h and gusts approach 100 km/h. Power outages are likely with the heavy snow and damaging wind gust threat.

Snowfall eases by Monday evening, with any mixing that occurs changing back to snowfall late Monday as cool air funnels in.
Temperatures will drop Monday night, with wind chills reaching the -20s in the north and minus teens in the south.
