US, Canada: Storm system to bring heavy snowfall and strong winds to portions of the US and Canada through Dec. 25 /update 1

Event

A potent storm system will bring snow to portions of the Midwest, Northeast, Appalachia, and Ohio Valley regions of the US, as well as the Prairie region, Ontario, and Quebec in Canada. The affected areas include the southern portions of Alberta, Saskatchewan, Manitoba, and Ontario, as well as southwestern Quebec, in Canada, as well as eastern Idaho, western Montana, southeastern and the Upper Peninsula of Michigan, northwestern Wisconsin, Minnesota, northeastern North Dakota, eastern South Dakota, western New York, central and western Pennsylvania, Ohio, eastern Kentucky, West Virginia, southwestern Virginia, eastern Tennessee, and far western North Carolina. As of the afternoon of Dec. 22, snow is falling across Idaho and Montana in the US, and southern Alberta, Saskatchewan, and Manitoba in Canada. Forecast models indicate the area of precipitation will gradually spread eastward over the coming days, arriving in North Dakota and Ontario early Dec. 23, South Dakota and Minnesota midday Dec. 23, and Wisconsin and Michigan early Dec. 24. A secondary area of snow will develop beginning midday Dec. 24 in an area including western New York, central and western Pennsylvania, eastern Ohio, eastern Kentucky, West Virginia, southwestern Virginia, eastern Tennessee, and far western North Carolina, The precipitation is initially expected to start as rain in those area. The system should fully depart the region by the afternoon of Dec. 25. Some uncertainty remains in the forecast track of the system and snow are subject to changes over the coming days.

Government Advisories
As of Dec. 22, the US National Weather Service (NWS) has issued blizzard warnings for portions of southwestern Minnesota and eastern South Dakota. Winter storm watches are in effect across portions of eastern North Dakota, northern and central Minnesota, northwestern Wisconsin, and the areas of Ohio, Pennsylvania, and New York along lakes Erie and Ontario. Additionally, Environment Canada has issued snowfall and winter storm warnings across southern Alberta, Saskatchewan, Manitoba, and Ontario. 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 portions of interior southwestern Ontario; locally higher totals of up to 80 cm (31 inches) are possible. 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, northeastern Minnesota, and along Lake Erie and Lake Ontario. This area includes Calgary and Regina. Lower amounts of 5-15 cm (2-6 inches) are expected in North Dakota, South Dakota, and near the Appalachian Mountains in the eastern US. In addition to the heavy snow, strong wind gusts are likely 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. 25. Traffic and commercial trucking delays are possible along regional highways including the I-29, I-35, I-40, I-64, I-69, I-70, I-71, I-75, I-76, I-77, I-79, I-80, I-81, I-86, I-90, I-94, and I-99 corridors in the US, as well as the Trans-Canada Highway, Yellowhead Highway, Macdonald–Cartier Freeway, and Alexander Graham Bell Parkway 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 Winnipeg (YWG), Regina (YQR), Minneapolis (MSP), Toronto (YYZ), Pittsburgh (PIT), Detroit (DTW), Cleveland (CLE), and Columbus (CMH).

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. 25. 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