Snowy in Seattle? Cold snap on the way

A storm bearing a threat of snow and some of the coldest temperatures seen since 1990 is expected to arrive Saturday evening in the Seattle area and declare winter is here.

The Seattle area could see rain turning into snow as early as Friday evening, with areas in higher elevations bracing for as much as 8 inches by Saturday evening, National Weather Service meteorologists said.

With cold air moving south from British Columbia, Saturday-morning temperatures are expected to hover around freezing, with highs in the 30s, but by Saturday evening, the mercury will plunge into the 20s, forecasters say. Sunday will offer similarly chilly temperatures in the 20s and low 30s.

Meteorologists say the Puget Sound area may wake on Monday to bone-chilling temperatures around 20 degrees with highs that day in the upper 20s to low 30s.

A dry, clear cold snap is expected to continue next week, said Brad Colman, head meteorologist for the National Weather Service in Seattle. It could be the coldest air to hit the region since December 1990, he said.

"It really is a major winter blast," he said.

Meteorologists put out a winter-storm watch Thursday for Central Puget Sound and a winter-storm warning in the mountains. The Central and Southern Cascades are forecast to get blasted by 1 to 2 feet of snow over the weekend, while the North Cascades also will see their fair share, with about a foot of new snow. High winds also may gust through the Strait of Juan de Fuca and the Central Coast, which are on a high-wind watch. The San Juan Islands and areas near Bellingham are also on a high-wind watch for Saturday.

Driving conditions will be treacherous throughout the region, state officials say, with blowing, drifting snow in the mountains and slippery, snowy roads in the metropolitan areas.

The state already temporarily closed Chinook and Cayuse passes and the North Cascades Highway on Thursday because of the coming storm. The state has about 100 plows covering state roadways in five Western Washington counties, and crews have been preparing for the first winter storm and are ready to go around the clock, said Patrick Moylan, maintenance and operations manager for the state transportation department.

Neither Snoqualmie nor Stevens passes are likely to close for extended periods over the weekend because there's not yet enough of a snowpack to pose an avalanche danger, Moylan said. But major traffic accidents from slippery roads still could shut them down for a couple of hours at a time.

Weather and state officials are asking people to consider delaying travel plans this weekend. If you must go, look at the weather forecast and conditions (www.wsdot.wa.gov/traffic/weather) before heading out and prepare by filling your gas tank, making sure there is coolant in the radiator and carrying chains and emergency supplies such as food, water and a blanket.

Those itching to get out in the snow for recreation also need to be cautious. Weather conditions are likely to be bad enough that people should not venture beyond developed areas, said Mark Moore, director of the Northwest Weather and Avalanche Center.

The flurries of snow on the way probably will be light and fluffy, and Crystal Mountain is the only ski area considering opening this weekend, Moore said. If it does open, the runs would be limited to the lower lifts because of cold temperatures and wind chill, he said.

"Conditions will be brutal out there," he said.

Even people who stay home this weekend should prepare, officials said, taking precautions such as protecting pipes from freezing and ensuring that water for outdoor animals is not iced over.

"It's an important storm," Colman said. "We haven't had this cold for a long time."

Nicole Tsong: 206-464-2150 or ntsong@seattletimes.com