Dangerous ice storm threatens over 1 million in Pacific Northwest Thursday: 'This has us concerned'
Ice Storm Warnings cover over a million people in the central and southern Willamette Valley, including Eugene and Salem, while Winter Storm Warni
What is freezing rain?
Snow gets a lot of attention during winter storms, but an ice storm of freezing rain can have a more significant impact on a region.
FAST FACTS:
- Dangerous freezing rain event triggers Ice Storm Warnings for over 1 million across much of the Willamette Valley.
- NWS warns Portland area commuters don't be complacent with a dry Thursday morning drive as storm arrives there midday.
- Freezing rain lingers into Friday and could return over the weekend.
PORTLAND, Ore. — A potent winter storm is threatening a mix of significant freezing rain and accumulating snow across a swath of the Pacific Northwest - including the Portland area - on Thursday, bringing warnings of power outages and multiple dangerous commutes.
An area of low pressure swirling off the Pacific Coast that is connected to an atmospheric river storm bringing torrential rains to California Thursday will also spread moisture into western Oregon and southwestern Washington.
(FOX Weather)
The approaching storm is carrying relatively mild air, but cold air is deeply entrenched in western Oregon, which has been in a week-long arctic chill. Temperatures are dropping into the mid-20s Wednesday night and will struggle to reach freezing Thursday morning as easterly winds pull in even more arctic air from Eastern Oregon via the Columbia River Gorge.
As the warm rain pushes in over the freezing surface, it’s a classic recipe for freezing rain - and a lot of it.
(FOX Weather)
Ice Storm Warnings cover over a million people in the central and southern Willamette Valley, including Eugene and Salem, for as much as 0.2-0.3 inches of ice accretion. Freezing rain will likely be falling by their Thursday morning commute, making glazed roads a danger. Power outages from ice-coated trees and power lines could follow.
HOW MUCH ICE IS NEEDED TO KNOCK OUT POWER, DAMAGE TREES?
The precipitation is likely to hold off until just after the Thursday morning commute in the Portland and Vancouver metro area, but even that carries its own risk.
"Precipitation will likely begin as snow for the northern Willamette Valley and Portland/Vancouver metro around 9-10 AM (Thursday) before switching over to freezing rain in the early afternoon, potentially mixing in with sleet at times," the National Weather Service in Portland wrote in its Wednesday evening forecast discussion. "This has
us concerned that folks living in the Portland/Vancouver metro will wake up before 9 AM, notice it is still dry out and head to work, then have a very difficult time trying to commute back home in the evening as there will likely be some snow and ice on roads, resulting in hazardous travel conditions."
WHAT IS THE DIFFERENCE BETWEEN SNOW, SLEET, AND FREEZING RAIN
Snow accumulations around Portland are expected to top out around an inch before the change to freezing rain, which is forecast to accrete to about 0.1-0.2 inches. A Winter Storm Warning is in effect there through late Friday morning.
(FOX Weather)
In addition, strong easterly winds could reach 45-60 mph gusts in the eastern Portland suburbs along the cold outflow of the Columbia River Gorge, extending freezing rain threats and dropping wind chills into the teens.
The freezing rain threat lasts through Thursday night and into about midday Friday before the storm pushes off to the east and the region temporarily dries out. Light snow up to about an inch could reach as far north as the southern Puget Sound region south of Seattle before drier air works its way there too.
However, another storm heading into the Northwest for the weekend may present a renewed ice threat in the eastern Portland area near the Columbia Gorge outflow until much milder air sweeps into the Northwest and ends any lowland wintry weather threat.