Forecast for snow is changing to rain

More snow isn't coming to Seattle, after all.

Tonight's storm, forecast to drop one to three inches of snow on the city this evening, is instead bringing freezing rain and sleet, changing to rain overnight.

Snow is still expected in northern Snohomish County and counties farther north, two to four inches of snow is expected through the night, said Jim Prange, a National Weather Service meteorologist in Seattle.

The snow was expected to begin falling early this evening in Seattle, but the National Weather Service now says slightly higher temperatures will likely mean freezing rain and sleet instead, turning to rain after midnight.

Freezing rain early Thursday could make the morning commute hazardous.

The snow expected to fall tonight and tomorrow morning is the result of warm, moist air moving off the Pacific Ocean that will move overtop the frigid, arctic air that has been hovering over the region since Sunday.

Around 4 a.m. Thursday, the snow is expected to begin turning to freezing rain — and is expected to freeze on contact since the ground surface will take longer to warm, Prange said.

"It will gradually warm up as Thursday progresses but it'll be really messy 'til we get to that point," he said.

Meanwhile, only a trace of light snow fell overnight so November's precipitation tally at Seattle Tacoma International Airport stands at 15.26 inches, just shy of the 15.33 inches of rain that made December 1933 the wettest month since weather record-keeping began in the 1890s. The 1933 record was set at the Federal Building in Seattle, where rain was measured until the 1960s. The National Weather Service began measuring rainfall at the airport in 1945.

Seattle's cold spell — not just its rainfall — is one for the record books.

At 4 a.m. today, the temperature at Seattle-Tacoma International Airport plunged to 18 degrees, breaking a 31-year-old record of 22 degrees, making it the coldest Nov. 29 in Seattle history.

Although the storm that started Sunday and wrapped up Tuesday trapped some rural residents in their homes and caused traffic backups nearly everywhere, authorities were surprised by the low number of serious weather-related incidents.

Nonetheless, two 16-year-old boys died of apparent carbon-monoxide poisoning near Port Angeles on Tuesday. The teens were inside a garage that was being heated by a gas combustion generator, according to the Clallam County Sheriff's Office. The boys' names were not released.

In SeaTac, a 60-year-old Federal Way man was critically hurt Monday night after a van struck him while he was stopped on Highway 509, Merrill said. The driver of the van apparently lost control and the man was pinned between his car and the van. Both of his legs had to be amputated at Harborview Medical Center in Seattle, Merrill said.

Between Monday night and Tuesday morning, King County troopers responded to 653 calls for assistance, 242 of those because of collisions. Troopers impounded more than 40 abandoned cars, Merrill said.

In Snohomish, Skagit and Whatcom counties, troopers responded to 687 collisions between Sunday and Tuesday, said Trooper Keith Leary.

In Pierce County, a man was pinned against a guardrail Tuesday after another car slid into him on Highway 16, said Trooper Bill Ashcraft.

Motorists were seething Tuesday over the previous night's rush-hour delays — lasting eight hours for some drivers.

Doug MacDonald, state transportation secretary, said officials handled the weather appropriately.

The state Department of Transportation had been expecting a typical Puget Sound snowfall, where snow is often melted by heavy auto traffic and mild temperatures. Instead, it was caught by surprise when temperatures plummeted into the 20s while traffic was at its heaviest.

Traffic made it tough for state plows and sanders to reach Interstate 405, the site of some of the worst backups in King County. Compounding the problem, crews also had to clear Highway 512 in South King County and Highway 9 in East Snohomish County, both hit by deep snow, while Monday Night Football fans added traffic to I-405 and I-5.

The state owns 45 pieces of winter equipment — mostly plows and de-icing trucks — to handle winter road conditions in King County and has 19 pieces of equipment in Snohomish County, said Patrick Moylan, the state Department of Transportation's maintenance manager for its northwest region. There are at least 19 pieces of equipment in snowy Whatcom County, where cold, windy weather has caused drifting snow, especially on Highway 542 leading to the Mount Baker ski area, he said. There are 18 pieces of winter equipment in Skagit and Island counties, where wet, heavy snow has downed trees along Highway 9, Moylan said.

If today's storm hits during rush hour, it will be a challenge to clear the roads.

"We are ready and we're hoping whatever we get tonight will occur late enough that we can get it off the roads before morning," he said.

Because of record-low temperatures overnight, the city of Seattle opened Seattle Center, City Hall and the Frye Hotel to the homeless. Overflow space was available at the Compass Center near downtown, according to the mayor's office.

Numerous school districts — including Seattle, Shoreline, Everett, Bellevue, Federal Way, Lake Washington and Issaquah — were closed Tuesday. Most of those, including Seattle, Bellevue, Lake Washington and Issaquah, are closed again today.

As of late Tuesday, about 21,500 homes in northern Puget Sound counties remained without power.

Snohomish County PUD had at least 50 crews working on mostly small and scattered outages throughout the north end of the county, said spokesman Neil Neroutsos.

Farther north, about 7,000 customers of Puget Sound Energy customers were in the dark, said spokesman Roger Thompson.

Power was restored late Tuesday to part of Concrete. Thompson said crews hoped to restore power to most other customers by early this morning, but some could remain dark through today.

Tom Sheehan, Skagit County's emergency-management director, said he was worried about Lake Cavanaugh, east of Mount Vernon, and Lake Tyee, near Concrete. Roads were closed to both isolated communities, and neither had power as temperatures were expected to drop into the teens.

Medicines were driven in by snowmobiles to the communities, and at least one resident was taken out for a dialysis treatment, he said.

Though the morning commute on Thursday could be tricky if the freezing rain covers local roads with ice, by Thursday night, the warmer air should turn precipitation into rain, said Prange of the Weather Service. Friday and Saturday are both expected to be partly cloudy with high temperatures in the mid 30s and low 40s.

Come Sunday, yet another system will be moving into the area, Prange said.

"But it looks like it's just going to be wet, not white," he said.

Times staff reporter Mike Lindblom contributed to this report.

Sara Jean Green: 206-515-5654 or sgreen@seattletimes.com