Ice storm to snarl travel in Seattle, Portland before Christmas
AccuWeather forecasters say atmospheric conditions may come together to deliver a significant ice storm to the Northwest ahead of the holiday weekend.
An ice storm will continue to affect the Pacific Northwest into the Christmas weekend, making for dangerous travel across the region for the second time in a week.
A wintry mix, comprised of mostly freezing rain overspread the Interstate 5 corridor of Washington and northern Oregon during Thursday night. A buildup of ice ranging from 0.10 to 0.33 of an inch has occurred on elevated surfaces from Bellingham, Washington, to Seattle and Portland, Oregion, and has caused icy travel in much of the region.
In Portland, Oregon, precipitation briefly began as sleet before quickly mixing with and changing to freezing rain. A few flurries fell in Seattle at the onset of precipitation on Thursday night, but also rapidly changed to freezing rain.
"The buildup of ice may continue into Friday night," AccuWeather Senior Meteorologist Bob Larson said of major cities west of the Cascades.
Olympia is one location in Washington where the ice accumulation could be heavy and damaging. Farther south, Astoria and Salem are a couple other cities in Oregon, in addition to Portland, where forecasters are most concerned about ice accumulation.
East of Portland, along Interstate 84, precipitation may start as snow and sleet in some areas, before changing over to freezing rain, prolonging the risk of slowed travel through Friday night.
The accumulation of ice will make roads treacherous, and with holiday travel in full swing, more people than normal will be on the roads. Road conditions could become extremely difficult and dangerous given the prolonged period of ice.
"The ice could delay the expected arrival of holiday packages," cautioned Larson.
In addition to the ice, winds are expected to increase as well. The buildup of ice combined with the strong winds will raise the risk of power outages. This could even create issues for those who decide not to travel, as some homes may not have heat if the electricity is not working.
Warmer air will gradually work into the Northwest Friday night and Saturday, which will be enough to cause freezing rain to transition to plain rain in coastal locations. However, the ice will not instantly melt when the temperature rises above freezing. Furthermore, when the ice does begin to melt, there will be a risk of ice falling from tall buildings and bridges in cities and trees in wooded areas.
Temperatures will shift from the 20s F on Friday in Portland to the lower 50s on Christmas Eve and Christmas Day. High temperatures in Seattle reached only 26 degrees on Thursday. Temperatures will trend higher into the upper 30s on Friday and the lower 50s by Saturday.
Farther inland, the cold air will be slower to erode, allowing freezing rain to continue for an extended period, forecasters say. The highest likelihood of freezing rain lasting through Friday night and into Saturday morning will be in the Columbia River Gorge to the east of Portland.
Cold air at ground level is expected to become trapped in the gorge. This will allow rain to continue to freeze on contact as it falls through Friday night and even into Saturday. Temperatures throughout the region should finally rise above freezing by Saturday afternoon.
Heavy rain in parts of the area on Christmas Eve could lead to localized flooding, especially if any storm drains are clogged with ice. Any lingering ice will melt over the weekend as rain is forecast to continue in the Northwest on Sunday and Monday then extend southward into California by Tuesday.
This is the second round of adverse weather conditions the region has already dealt with this week. On Tuesday, heavy snow spread across the Northwest as well as across the border in Canada, where travel chaos occurred at the airport in Vancouver, British Columbia.
The Washington State Department of Transportation (WSDOT) was busy keeping up with the snow on Tuesday, particularly in the mountains. The agency said a stretch of Interstate 90 through Snoqualmie Pass was closed in both directions Tuesday due to multiple vehicle spinouts and snowy conditions. By Wednesday morning, I-90 eastbound had been reopened, and avalanche control had been completed, WSDOT said.
In Seattle, rain changed to snow before noon on Tuesday, and 0.6 of an inch of snow had accumulated by the end of the day. An additional 0.3 of an inch fell on Wednesday, and a high temperature of just 30 degrees Fahrenheit was 16 degrees below normal for Dec. 21.
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