State College, Pa. - AccuWeather reports a major snowstorm is set to ride the leading edge of cold air over a large part of the West and the northern Plains Thursday into Saturday. The storm will evolve into a blizzard as it emerges from the northern Rockies.
Snow will fall over thousands of square miles of the West initially, then over the northern Plains.
Snow has already covered the landscape around Boise and will continue on to Pocatello, Idaho, in the Snake River Basin into Thursday night.
Snow was also spread over the northern and eastern portions of the Great Basin Thursday.
A major snowfall is forecast for Salt Lake City spanning later Thursday into Friday. An accumulation of a half a foot or more is likely.
The bulk of the snow is heading north of Denver, but enough snow can fall with plummeting temperatures to make for icy roads during Friday. A general 3 to 6 inches of snow is forecast for the Colorado Rockies.
The latest snow map for is available on AccuWeather.com's Winter Weather Center.
Motorists should expect slow travel over the major cross-country arteries of the West, including I-15, I-25, I-70, I-80, I-84, I-90 and I-94.
There is the potential for close to a foot of snow over portions of Idaho, Montana, Wyoming, northwestern Nebraska, the Dakotas and into northwestern Minnesota. Heavy snow will also graze Canada from southern Alberta to Northwest Ontario.
Other cities in the path of the snowstorm include Miles City, Mont.; Grand Junction, Colo.; Casper, Wyo.; Rapid City, S.D.; Bismarck and Fargo, N.D.; and International Falls, Minn.
In some locations, the snow will be accompanied by gusty winds that can cause drifting and low visibility for several hours.
More general blizzard conditions will unfold as the storm tracks northeastward over the Dakotas and northwestern Minnesota.
Very difficult, of not dangerous travel will unfold over portions of I-90 in western South Dakota and I-94 over much of North Dakota Friday.
Warmth preceding the storm will cause the initial snow to melt on the roadways. However, temperatures will plunge as the storm rolls to the northeast, in some areas temperatures will be 40 to 50 degrees lower than highs experience Thursday. Ice will form in some areas and will be hidden by the snow over the northwestern flank.
In the wake of the storm, many areas from the northern Rockies to the northern Plains will have highs in the single digits and teens with nighttime lows below zero into next week.
The snowstorm will ride north Omaha, Des Moines and Minneapolis, but a push of much colder air will follow.
The storm will drive freezing air into Southern California and Arizona.