US, Canada: Storm system to bring heavy snowfall to portions of the US and Canada, from Dec. 21-24

Event

A storm system will bring snow to portions of the Midwest and Intermountain West regions of the US, as well as the Prairie region of Canada. The affected areas include the southern portions of British Columbia, Alberta, Saskatchewan, Manitoba, and Ontario in Canada, as well as the Upper Peninsula of Michigan, northern Wisconsin, northern Minnesota, northeastern North Dakota, western Montana, eastern and central Idaho, and northern and central Washington in the US. As of morning Dec. 21, snow has begun to fall in interior British Columbia while rain is falling in Washington state and in lower elevations. Forecast models indicate the area of precipitation will gradually spread eastward over the coming days, arriving in Alberta late Dec. 21, Idaho and Montana midday Dec. 22, Saskatchewan late Dec. 22, Manitoba and North Dakota early Dec. 23, Ontario and Minnesota midday Dec. 23, and Wisconsin and Michigan early Dec. 24. Some uncertainty remains in the forecast track of the system and snow and ice amounts are subject to changes over the coming days.

Government Advisories
As of Dec. 21, the US National Weather Service (NWS) has issued winter storm watches for eastern North Dakota and western Minnesota. Additionally, Environment Canada has issued snowfall and winter storm warnings across British Columbia, Alberta, and Saskatchewan, while winter storm watches are in effect in Manitoba. Authorities will likely issue new alerts or update/rescind existing advisories as the winter storm transits the region over the coming days.

Hazardous Conditions
The latest forecast guidance indicates that accumulations of 30-50 cm (12-20 inches) of snow are expected in the hardest-hit areas, including the Canadian Rockies of Alberta and British Columbia Accumulations of 15-30 cm (6-12 inches) are expected across the rest of southern British Columbia and Alberta, as well as Manitoba, Saskatchewan, Ontario, and northeastern Minnesota. Lower amounts of 5-15 cm (2-6 inches) are expected farther south in portions of North Dakota, Idaho, and Montana where the snow is likely to mix with rain, especially in lower elevations. In addition to the heavy snow, strong wind gusts could lead to periods of blowing and drifting snow. Blizzard conditions are possible. Sporadic power outages are likely throughout the affected area.

Transport
The inclement weather will likely cause widespread ground and air transport disruptions across the affected area through Dec. 24. Traffic and commercial trucking delays are possible along regional highways including the I-15, I-29, I-35, and I-90 corridors in the US, as well as the Trans-Canada Highway and Yellowhead Highway in Canada. Difficult and potentially dangerous driving conditions are also likely on secondary and rural roadways in the affected states as maintenance crews prioritize clearing major routes. Authorities could close stretches of highway if driving conditions become too hazardous. Gusty winds may threaten to topple high-profile vehicles throughout the affected area. Heavy wet snow and strong winds could bring down power lines and trees with foliage. Flight delays and cancellations are likely due to ground stops and deicing operations at regional airports including, but not limited to, those serving Calgary (YYC), Winnipeg (YWG), Regina (YQR), and Duluth (DLH).

Advice

Monitor local media for updated weather information. Verify road conditions before driving in areas where heavy snowfall is forecast. Allow extra time to reach destinations in these areas and carry an emergency kit and warm clothes if driving is necessary, especially on secondary or rural routes that could become impassable. Plan accordingly for delivery delays if routing shipments by truck through the affected area through at least Dec. 24. Confirm flights. Charge battery-powered devices in the case of prolonged electricity outages.

Resources

US National Weather Service
US Road Conditions
Meteorological Service of Canada