Now this: up to 6 inches of new snow; more Tuesday

The National Weather Service is predicting another 3 to 6 inches of snow through overnight, from Everett to Tacoma.

Officials are advising area residents to stay off the roads unless absolutely necessary.

Many accidents were reported along Interstate 5, and on Interstate 405, some SUVs had gone off the road.

As conditions deteriorated, Alaska Airlines and Horizon Air shut down flights at Seattle-Tacoma International Airport. Other carriers were operating, but most of those flights were also canceled due to weather problems here and elsewhere, said Port of Seattle spokesman Perry Cooper. Thousands of people have been stranded.

Alaska, Horizon and other carriers also were running low on de-icing fluid, while shipments remained stranded in Montana and east of the Cascades.

Airport veterans say the disruptions are the worst in 30 years, Cooper said.

Amtrak and Greyhound passengers remain stuck, here, too.

"As far as service resuming, that's going to depend on the weather," said Eric Wesley, a spokesman for the company. "We won't put anybody on the road until it's safe."

Those holding bus tickets can use them when service resumes. Tickets are good for up to one year.

Passengers stranded at Greyhound stations are getting help from the Red Cross, Wesley said.

Amtrak's Cascade rail service between Eugene and Vancouver, B.C., was canceled Sunday due to weather. A spokesman for the company said Sunday afternoon that it was still unclear whether operations would resume Monday.

As the snow continues to fall, low temperatures tonight are likely to dip into the upper 20s with southeast winds of 10 to 15 mph.

Monday is expected to be fairly clear and cold, and then — a chance of more snow Tuesday.

The when's-it-going-to-end snow follows a pre-dawn freezing rain that left a slippery layer of ice over earlier snow. Roads and sidewalks have been left worse for the mix.

Crews are working to keep the most-traveled main arterials clear, but in many cases, it's a losing battle. Driving is rough on the main roads, even for those experienced in ice and snow. Side streets — even flat ones — are worse; the snow is deeper, and there is ice underneath.

There are large drifts of snow in some rural areas. In the Sultan area, some drifts are up to 8-feet deep.

Today's snow is piling onto what accumulated overnight. Here are some of those snow totals from Saturday into early Sunday morning, according to National Weather Service meteorologist Johnny Burg:

• Seattle: 5 inches

• Sand Point (at the Weather Service office): 3 inches

• West Seattle: 4 inches

• Rainier Beach: 5 inches

• View Ridge: 6 inches

• East Bellevue: 4 inches

• Bothell: 4 inches

• Redmond: 3 inches

Worries of extensive power outages followed predictions Saturday of sustained, high-powered winds. But for the most part, the windy conditions didn't last long Saturday night.

Washington Emergency Management spokesman Rob Harper said fewer than 5,000 people lost power statewide, and those were mostly scattered outages. Relatively few are still without power.

Here is other information to help you plan:

Sea-Tac open

Travelers should contact their airline for their flight status.

No, or very few, hotel rooms are available near the airport. Also, officials said, airport vendors are having trouble getting deliveries, so people coming to the airport should come prepared.

Metro bus service

King County Metro Transit is operating about half of its normal bus schedule, officials announced this morning.

Officials recommend that before you leave home, you check the Metro Web site, transit.metrokc.gov/ to see if your bus route running today, and if a special snow route is in effect.

You can also call the Metro Customer Information Office at 206-553-3000, but call volumes are high and there may be a wait to talk with someone who can help plan your trip.

Metro is focusing on providing bus service on cleared highways and arterials, and to major transit centers and park-and-ride lots that normally have Sunday service. Be prepared to board buses mostly at those major transit centers, on flat arterials, or at the top or bottom of hills.

Snohomish County Community Transit

Bus service in Snohomish County is "severely limited," officials.

Heavy snowfall has made many areas impassable, including Stanwood, Darrington, Mill Creek and Edmonds, officials said earlier today.

When service does begin, most routes will operate only from park-and-rides, to park-and-rides along Interstate 5 or Interstate 405. There will be delays.

Also, Community Transit officials say, there will no service on most side streets in south Snohomish County.

More specific information about each route will be posted at www.communitytransit.org as it becomes available.

If your stop is on a hill, wait at the top or bottom of the hill and flag down your driver. Also, the "kneeler," the feature that raises and lowers the front of the bus for easier boarding, cannot be used in very cold conditions.

The Associated Press and staff reporters Steve Miletich, Maureen O'Hagan and Nick Perry contributed to this report.