The nation's first major snowstorm of the season is expected to impact thinly populated northern U.S. areas Tuesday through Thursday.
The storm will initially hit the Pacific Northwest and northern Rockies before moving into the northern Plains in the coming days, predictions say.
AccuWeather predicted "near-blizzard conditions" and travel disruptions in at least six states. The National Weather Service predicted 2 feet of snow in certain regions.
The storm brought winter storm warnings and watches to the Cascades and northern Rockies on Tuesday.
With "some some disturbances to everyday life," the Great Falls, Montana, weather service office said "mobility might be very difficult to impossible and some vehicles may need tire chains. Backcountry hikers should have the right gear and knowledge and seek alternatives."
Blizzards have reduced visibility due to heavy snowfall and powerful winds. The weather service defines a blizzard as 35 mph winds and snowfall that decreases visibility to a quarter mile or less for three hours.
The meteorological office said 2.5 million people were under winter weather alerts for the storm as of midday Tuesday. Washington, Oregon, Idaho, Montana, Wyoming, and North Dakota experience it.