First heavy snow, ice storm in northwestern US to snarl travel

By Alex Sosnowski , AccuWeather senior meteorologist

December 6,2016, 2:19:09PM,EST

 

The first substantial snow and ice storm of the season will hit travel hard along the Interstate 5 corridor, as well as the interior northwestern U.S. by Thursday.
While the storm will begin as rain along the immediate coast of Oregon during Wednesday night, enough cold air will be in place for an icy mix to develop east of the Coast Range.
"Along I-5 in Oregon, especially from Eugene to Salem and Portland, travel will be slippery during the Thursday morning commute," according to AccuWeather Senior Meteorologist Brett Anderson.

As the storm expands farther to the north and east, more of a wintry mix of snow, sleet and freezing rain will occur during the midday hours on Thursday.
The swath from Tacoma to Seattle and Bellingham, Washington, will likely receive its first inch or more of snow and sleet of the season, before a change to rain occurs during the night. Part of this area received its first coating of snow on Monday.
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"For the I-5 corridor around Puget Sound, the evening commute Thursday will be slippery," Anderson said.
Several inches of snow are in store for the Olympic Range with a foot of snow possible over the peaks, prior to a change to rain.
The hilly areas in the I-5 region, as well as bridges and overpasses, are the most likely to become slippery.
"Icy conditions may linger into the evening commute around Portland," according to AccuWeather Senior Meteorologist Dave Houk.
The combination of snow and ice, followed by rain and a low cloud ceiling, will lead to airline delays at Seattle-Tacoma International Airport.
Farther inland, cold air will hold on. Areas east of the Cascades can expect a prolonged period of snow and/or ice as a result.
"Icy travel is likely to persist through the Columbia River Gorge into Thursday night," Anderson said.
Enough snow to shovel and plow will fall on Spokane and Yakima, Washington, as well as Pendleton and The Dalles, Oregon.
Travel along the I-82, I-84 and I-90 corridors will be hazardous, prior to temperatures approaching the freezing mark, Anderson stated.

Even as temperatures creep upward and snow transitions to ice and rain, the weight can lead to power outages, due to falling trees and tree limbs from late Thursday to Friday.
As a second storm rolls in from the Pacific, rain will fall along the coast, and either rain or a rain, ice and snow mix will occur inland as far to the east as Idaho on Friday.
Where a few inches of snow is followed by drenching rain, urban and poor drainage area flooding will occur.
Meanwhile, the air will remain cold enough for heavy snow to fall over the Cascades and Bitterroots. From 1 to 2 feet of snow will fall over the high country of the Cascades with a foot of snow likely over the ridges in the Blue Mountains and Bitterroots.
It is possible the passes in the Cascades and Bitterroots may close for a time, due to the heavy snowfall rate.
Farther south, at Donner Pass, California, and Siskiyou Summit, Oregon, icy conditions to start will be followed by plain rain later Thursday. Both of these passes should remain above freezing during Thursday night and Friday.