PENDLETON - Just when you thought the blue skies held promise, the National Weather Service has upgraded its winter storm watch to a winter storm warning.
For the foothills of the Blue Mountains, including Pendleton and Walla Walla and Heppner, there's a freezing rain advisory in effect from 9 a.m. to 4 p.m. Thursday. Forecasters say it should change to rain late Thursday afternoon.
They predict ice accumulations of up to one-quarter inch.
"This storm is coming off the Pacific Ocean, bringing with it warm, moist-laden air that's riding on top of cold air trapped on the east side of the Cascades, particularly in the lower Columbia Basin," said Joe Solomon, meteorologist at the National Weather Service Forecast Office in Pendleton.
He said the precipitation will start as snow, but as the air warms aloft, the snow in the atmosphere will melt, resulting in freezing rain.
The freezing rain shouldn't last long in Pendleton, Solomon said.
"The bigger impact will be from north central Oregon, up along the east slope of the Cascades, to Yakima, Ellensburg and Tri-Cities," he said. "They're going to be in the cold air the longest."
In the Lower Columbia Basin, including Hermiston, Boardman, Arlington and Tri-Cities, Wash., forecasters say the storm warning is in effect from 9 a.m. to 10 p.m. Thursday. They predict snow accumulations of 3-5 inches along with possibly up to one-quarter inch of ice.
For the Eastern Columbia River Gorge, including The Dalles and White Salmon, Wash., the warning also is effective from 6 a.m. to 10 p.m. Thursday, but forecasters say snow accumulations could be 4-6 inches along with a quarter inch of ice.
Eastbound, it's expected to be even worse. In the northern Blue Mountains, including Meacham and Tollgate, the winter storm warning is in effect from 9 a.m. Thursday to 9 a.m. Friday. Forecasters expect 5-9 inches of snow and up to one-quarter inch of ice.
In the southern Blue Mountains, including Ukiah, the winter weather advisory also is effective until 9 a.m. Friday. Accumulations of 3-5 inches are expected.