Flood watch issued for Seattle area as warmer weather threatens to melt snow

The National Weather Service this morning issued a flood watch for much of Western Washington, including the central Puget Sound area, as a strong, warm and wet Pacific storm approaches, creating the potential for urban and small-stream flooding.

The weather system, expected to bring high temperatures of about 40 degrees in the Seattle-Tacoma area today, will likely melt much of the region's snow and slush, creating the potential for flooded streets, homes and businesses.

Minor flooding could also occur along the Skokomish River as the snow level climbs to as high as 5,000 feet tonight, before dropping back to between 2,500 and 3,000 feet Saturday, the Weather Service said. Areas that have had a foot or more of snow may be particularly susceptible to flooding as the snow melts, according to the Weather Service. Residents have been advised to help clear storm drains and remove snow and slush from flat roofs.

Heavy accumulations of snow have been blamed on the Christmas Day collapse of a carport at a Bothell apartment complex and a portion of the roof at an Olympia high school. A carport roof collapsed on several cars at the Heritage Park Apartments on Northeast 190th Street in Bothell. Extent of the damage wasn't known, but no injuries were reported.

The flood watch, in effect from noon today until Sunday morning, is a step below a flood warning, which is issued when flooding is imminent or occurring. The flood watch is for King, Snohomish and Pierce counties, as well Clallam, Grays Harbor, Island, Jefferson, Kitsap, Lewis, Mason, San Juan, Skagit, Thurston and Whatcom counties.

Today's precipitation could begin as snow in areas above 500 feet, but is forecast to rapidly switch to rain by the late afternoon or evening.

Shortly before midnight Thursday, a 41-year-old West Seattle man was taken to Harborview Medical Center with life-threatening head injuries after he apparently rolled an all-terrain vehicle on a South Seattle street.

Police spokesman Jeff Kappel said the one-vehicle accident occurred about 11:30 p.m. in the 4000 block of Southwest Barton Street. Kappel said a second person, on another ATV, was riding in front of the injured man and did not see the accident.

Meanwhile, skiers and snowboarders are in for a treat this weekend: Three feet of new snow — maybe more — is expected to fall in the mountains between this afternoon and Sunday.

But anyone who hits the slopes should forgo backcountry excursions because the danger posed by avalanches will increase through the weekend, said Johnny Burg, a meteorologist with the National Weather Service in Seattle.

"If they're going into the backcountry," he said, "it'll be at their own risk. It could be very dangerous out there." Heavy, wet snow is forecast for both Snoqualmie and Stevens passes. It's snowing there now, with a couple of inches expected through the day.

Anyone who needs to cross Snoqualmie Pass should do it before 6 p.m. today — or wait until after 6 a.m. Saturday, said Mike Westbay, a spokesman with the state Department of Transportation. "That's when the snowfall will be the heaviest," with 8to 11 inches of snow expected to fall in that 12-hour period, he said.

Road crews will likely conduct avalanche-control work sometime after midnight, Westbay said. Depending on how much snow falls, "we may have to do it at different locations. We'll do it at least once this weekend, maybe more," he said.

From 6 a.m. to 6 p.m. Saturday, the forecast calls for another 2 to 3 inches of snow, Westbay said. Luckily, though, high winds aren't expected so there shouldn't be the kind of visibility problems that prompted a 10 ½-hour closure of Snoqualmie Pass last weekend, he said.

Saturday should be free of the snow and ice that have crippled much of the region since Dec. 13. Between that date and Christmas Eve, 12.8 inches of snow was recorded at Seattle-Tacoma International Airport. While that may seem like a lot to folks now recovering from cabin fever, it's still nearly 10 inches shy of the snowiest December on record: In 1968, 22.1 inches of snow was recorded at the airport.

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