Canada, US: Adverse winter weather conditions forecast across parts of south-central Canada and north-central US through at least Dec. 4 /update 1

Adverse winter weather conditions are forecast across parts of south-central Canada and north-central US through at least Dec. 4. More lake-effect snow is forecast across the Great Lakes, although they should be less active for parts of the recently harder-hit locations as the wind turns more southwesterly. At least 0.6 meters (2 feet) of new snow is possible downwind from Lake Michigan and Lake Erie over the coming days. The combination of heavy snowfall and gusty winds may cause blizzard conditions in places. Hazardous driving conditions are likely across the affected areas due to icy roads and reduced visibility caused by blowing snow.

As of late Dec. 1, the US National Weather Service (NWS) has issued winter storm warnings for southwestern Michigan and central New York and lake effect snow warnings for far northern Indiana, far southwestern Michigan, western New York, far northern Ohio, and far northwestern Pennsylvania. Winter weather advisories are in place across most of the rest of the affected area.

Environment Canada has issued red snow squall warnings (the highest level on a three-tier scale) off of Lake Nipigon through early Dec. 2 and across parts of far southern Ontario through early Dec. 3. Officials will likely issue new alerts or update/rescind existing advisories as weather conditions change over the coming days.

Eleven counties across western and central New York and parts of western Pennsylvania are under a state of emergency. Authorities closed some roads, including parts of Interstate 86 and 90 in Erie County, Pennsylvania, and limited speeds on highways. Gravenhurst Town in Ontario Province, Canada also declared a state of emergency due to a prolonged highway closure and limited emergency services. More than 60,000 people across southern Ontario are without power.

Snow accumulations are likely across the affected area. Lesser snowfall totals are possible where sleet and freezing rain mix with snow. In addition to the heavy snow, strong wind gusts could lead to periods of blowing and drifting snow. Sporadic power outages may occur throughout the affected area.

The inclement weather will likely cause widespread ground and air transport disruptions across the affected areas. Traffic and commercial trucking delays are probable along regional highways. Dangerous and challenging driving conditions are also likely on secondary and rural roads as maintenance crews prioritize clearing major routes. Authorities will likely close stretches of highways if driving conditions become too hazardous. Gusty winds will threaten to topple high-profile vehicles throughout the affected areas. Mountain passes and tunnels will probably be closed as a precautionary measure during periods of intense snowfall. The disruptive weather will likely cause delays and cancellations at airports in the affected regions. Heavy, wet snow and strong winds could bring down power lines and trees with foliage.