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Ice, rain and feet of snow to snarl travel in northwestern US

By Alex Sosnowski, AccuWeather senior meteorologist
December 30, 2017, 4:46:33 AM EST

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A major storm will unload heavy snow over the northern Rockies and northern Cascades with an icy zone in between into Friday night.

Motorists should anticipate substantial travel delays and possible closures along Interstate 90 and I-15 due to wintry conditions.

Episodes of rain and fog will slow travel along the I-5 corridor over much of Washington and Oregon into Friday night.

Static NW Storm Noon

From 1 to 4 feet of snow is forecast over the high country in Montana and northeastern Idaho. Meanwhile, 1-2 feet of snow may pile up in the high country of the northern Washington Cascades.

The storm will make for a winter wonderland for skiing interests. However, there is a considerable amount of risk for avalanches in the Washington Cascades and the Olympics due to the unstable, heavy load of snow, according to the Northwest Avalanche Center.

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Snow to create slippery travel in midwestern US into Friday night

For Snoqualmie Pass, Washington, snow, ice and rain are in store. For Lookout Pass, Montana, all snow will fall. Those who must venture through the mountains will need to make sure their vehicle is ready for severe winter weather, including tire chains.

A longer, but more southern route to the Central states may be a better option. No substantial precipitation is forecast along I-80 in the West into this weekend. Much of the I-84 corridor will be free of ice in Oregon.

In central Washington, the first part of the storm is forecast to bring a significant amount of ice and/or a wintry mix, prior to changing to rain. This includes the area from Yakima to Kennewick, Moses Lake and La Crosse, Washington.

"Roads and sidewalks will be hazardous, even after temperatures rise above freezing, since it has be so cold lately," according to AccuWeather Senior Meteorologist Kristina Pydynowski.

Enough ice my accrue to weigh down trees and power lines, which may result in sporadic power outages.

The storm will move away over the New Year's Day weekend.

Static US Weekend

Much of Saturday, Sunday and Monday are likely to be free of precipitation in the I-5 corridor.

Snow and ice will diminish in the Cascades on Saturday morning. Snow is expected to wind down over the northern Rockies during Saturday afternoon.

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