Most of those affected are customers of Puget Sound Energy, which said it had restored service to 87,000 customers who lost power in the snowstorm that began Wednesday. But the utility it could take into the weekend or later to get the power back on for the roughly quarter million additional homes and businesses still in the dark.

The National Weather Service said warming temperatures Friday should melt snow and ice in Western Washington lowlands as the forecast returns to normal — rain — into next week. Forecasters said the melting snow could cause urban and small stream flooding and fill the Skokomish and Chehalis rivers above flood stage by Saturday evening.

It was still snowing in the Cascades, with up to 2 feet possible in the mountains over the weekend. In Eastern Washington, forecasters expect more snow Friday or freezing rain before warming temperatures on Saturday raise the snow level above the valley floors in some areas.

Washington Gov. Chris Gregoire declared a state of emergency, authorizing the use of National Guard troops if necessary.

Oregon should see a break in the rainfall for some hours before another front comes in, said meteorologist Paul Tolleson in Portland, Ore.

“We’ll have decent fronts for the next 24 to 36 hours. It’ll be just enough rain to make people nervous,” he said.

The unusually strong system temporarily shut down Seattle’s airport Thursday. Alaska Airlines and Horizon Air canceled 310 flights to and from Seattle Thursday and Alaska Air said it was canceling 50 flights on Friday.

The storm knocked down so many trees that Washington State Patrol troopers brought chainsaws in their cruisers to hack through the obstacles.

It also left three people dead: a mother and her 1-year-old boy, killed after torrential rain swept away a car from an Albany, Ore., grocery store parking lot; and an elderly man fatally injured by a falling tree as he was backing an all-terrain vehicle out of a backyard shed near Seattle.

More than 50 downed trees on railroad tracks and the threat of more falling forced Amtrak officials to close service between Portland and Seattle on Thursday morning. The closure continued Friday.

Officials in Spokane declared a snow emergency, banning parking along arterials and bus routes beginning Thursday evening. The City of Seattle asked people to get home before dark if possible, fearing even worse icing conditions by nightfall. And authorities told pedestrians to be extra careful on sidewalks and to look out for “falling ice from trees, buildings and power lines.”

The National Weather Service said the last widespread freezing rain in Seattle was in December 1996.

The weather system also dropped snow on Washington’s Mount Rainier, where four people were reported missing. A search was suspended at nightfall but was to resume Friday.

In the Willamette Valley town of Scio, Ore., many residents evacuated as the city manager said water was pouring down Main Street.

Officials in the city of Turner, Ore., issued a voluntary evacuation order to people, asking them to flee to higher ground as floodwaters from the rising Mill Creek swept through town.

To the west of Oregon’s Coast Range, residents were being moved out of Mapleton, Ore., with a population of about 900.

Near Reno, Nev., winds gusting up to 82 mph pushed a fast-moving brush fire south out of control on Thursday as it burned several homes, threatened dozens more and forced thousands to evacuate their neighborhoods.

The storm system also brought blowing snow to northwest Colorado as high winds battered the Front Range, with more heavy snow expected over the weekend.

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By Jonathan J. Cooper and Manuel Valdes. Cooper reported from Albany, Ore. Associated Press writers Doug Esser, Ted Warren, Shannon Dininny, Rachel La Corte, Nigel Duara and Nicholas K. Geranios contributed to this report.