By Alex Sosnowski – AccuWeather
A highly unusual snow and ice storm for so early in the season will bring significant travel problems and disruptions to daily activities Thursday and Friday in the Interstate-84 corridor of Oregon, Washington and Idaho.
A storm more typical of January will arrive across the area late this week. With the arctic cold air that moved in earlier in the week, this will set the stage for a significant snow and ice storm farther inland. However, temperatures will rise above freezing rather quickly west of the Cascades.
Motorists should be prepared for an extended period of slippery travel in Portland and Salem, Oregon, on Thursday, due to a mix of snow, sleet and freezing rain. Travel will be dangerous Thursday into Thursday night.
Farther south, west of the Cascades in Eugene, Oregon, temperatures will remain above freezing during much the storm. While mostly rain will fall in this area, several hours of ice will occur from Eugene to Salem along I-5. Some roads that appear to be just wet may be coated with a thin layer of clear (black) ice.
Farther north along the coast, the wintry mix of precipitation will remain south of Seattle. Much of the storm will slip south of Olympia and Tacoma, Washington, with only very spotty showers of snow, ice and rain in store.
Farther east, from the Cascades, including the Columbia Gorge, to along the I-84 corridor through eastern Oregon and southern Idaho, the storm will bring several inches of snow, which will change to ice in some locations.
Localized snowfall from the Cascades to the mountains of central Idaho can reach 12 inches or more.
The snow and ice may be difficult to remove for a November storm due to the unusually low temperatures. Some of the snow will partially melt, only to refreeze.
Temperatures at the start of the storm east of the Cascades will be in the teens and lower 20s. Lows in the single digits and teens will occur in this area in the storm’s wake.
Travel along the I-84 corridor will be difficult if not dangerous. Freezing rain will accumulate and weigh down trees and power lines in some communities, which can lead to power outages.
Cities in the path of snow and/or ice include The Dalles, Hermiston and Pendleton, Oregon, as well as Boise, Idaho.
Snow will extend into southern Washington, east of the Cascades, brushing the cities of Walla Walla and Kennewick along part of the I-82 corridor.
A slight shift in the storm track to the north or south will mean the difference between heavy snow and/or ice versus rain or no snow at all.
After hitting the Northwest with heavy snow and ice, the storm has the potential to close passes and bring whiteout conditions to the Rockies in Colorado and Wyoming early this weekend before moving on to the central Plains.
People can monitor the progress of the storm by checking in at AccuWeather.com.
In the wake of the storm in the Northwest this weekend, melting and refreezing episodes will continue to bring hazards to pedestrians and motorists, as cold air will remain entrenched east of the Cascades.
Temperatures will continue to average 10 to 20 degrees below normal through this weekend and into next week in the wake of the storm in Washington, Oregon and Idaho.