Snowstorm, rapid freeze-up to create dangerous travel over Rockies, High Plains this week

By Renee Duff,

Snow, gusty winds and plummeting temperatures will accompany a new storm poised to travel from the Rockies to the High Plains this week.

This latest storm is expected to unleash less snow when compared with the one that buried Montana with over 4 feet in late September. However, the upcoming snowstorm will have a much broader reach and pose a wide array of hazards.


Disruptions to travel and daily routines are likely.

Cold air plunging in with the storm will allow snow to accumulate and travel to become slippery, not only in the highest elevations but also in the valleys.

Temperatures can plunge by 30-50 degrees Fahrenheit in the span of 12-24 hours as the cold air swiftly replaces preceding mild conditions.

Billings, Mont., is expected to have a high near 70 on Tuesday, before temperatures plummet into the 20s as snow falls at night.


"The mild to cold transition during the storm will tend to cause the snow to cling to the trees at first, which can lead to broken limbs and power outages," AccuWeather Senior Meteorologist Alex Sosnowski said.

Gusty winds whipping around the strengthening storm can also contribute to localized damage, as well as a heightened wildfire risk farther south.

The snow will become light and fluffy as the temperatures plummet, making it more susceptible to blowing and drifting in the winds.

In some areas, especially the lower elevations, precipitation may start as rain before transitioning to all snow.

Any wet areas on untreated roads and sidewalks may freeze up suddenly as it turns colder, creating a thin layer of ice that may be hidden by falling snow.

"Major U.S. highways that can be adversely affected by the storm include Interstate 15, I-25, I-80, I-90 and I-94, as well as Canada highways 1, 2 and 3," Sosnowski said.

The snowstorm will arrive in the Canadian Rockies late Monday and reach the northern Rockies of the United States on Tuesday and Tuesday night.

Cities that can expect at least several inches of snowfall and a period of slippery travel early this week include Calgary and Great Falls, Missoula, Bozeman and Billings, Mont.


"Some of the north- and east-facing slopes of the Sawtooth, Lewis and Clark, Bighorn, Bitterroot, Clearwater, Absaroka and Tetons are among the locations that may receive 6-12 inches of snow from the storm," Sosnowski said.

The Washington and Oregon Cascades and Blue Mountains are also likely to be whitened by fresh accumulation early in the week. Conditions could turn slippery for a time over I-90's Snoqualmie Pass.

AccuWeather meteorologists expect the storm to spread into the central Rockies and northern Plains during the middle and latter part of the week.

Rain can transition to snow as far south as portions of Colorado and as far east as the Dakotas, Nebraska and perhaps western Minnesota.

While it is too early to determine specific snowfall totals in these areas, people should begin preparing for a potential snowfall and rapid freeze-up that can disrupt travel plans, school and work routines.

Denver may experience its first snow of the season with this event.


Behind the storm, an Arctic high pressure system will settle over the Rockies, leading to record-challenging cold in many locations.

Spokane and Seattle, Wash.; Portland, Ore.; Boise, Idaho; Billings; Cheyenne, Wyo.; Denver; Rapid City, South Dakota; and Scottsbluff, Neb., are just some of the cities that could stamp new record lows into the history books during the middle and latter part of the week.

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