Windstorm watch: Big blow predicted for Thursday evening

Prepare to chase down knocked-over garbage cans and deal with flickering lights Thursday evening — forecasters say a windstorm is headed for Western Washington.

A high-wind watch has been issued for Thursday, meaning forecasters are about 50 percent certain that strong winds will blow through the region.

Andy Haner, a forecaster with the National Weather Service in Seattle, said it looks like the storm will peak between 5 and 8 p.m. Thursday — just in time for the evening commute. During that time, sustained winds could reach up to 35 mph, with gusts between 50 and 55 mph, he said.

"Any way you cut the pie, it's going to be a windy day. It's just a matter of how windy it's going to be," said Haner.

Cliff Mass, a professor of atmospheric sciences at the University of Washington, said the storm started out as a tropical disturbance, which is a typical source of windstorms in October. But Mass said the storm's center will pass far enough north to spare the Puget Sound area from severe winds.

"Here in the Puget Sound, this is not going to be one of the great windstorms at all," Mass said, calling it more of an "umbrella-breaker" than a storm that will cause major damage.

In addition to the wind, the Seattle area could get ½ to ¾ inch of rainfall during the storm, he said.

The blustery weather will affect most of Western Washington, from Bellingham to Olympia, but the strongest winds will probably be in the coastal areas, with gusts ranging between 60 and 70 mph, said Mass.

"While these winds are not huge, or uncommon for storm season, this situation is the first significant wind event of the season," said Seattle City Light spokesman Scott Thomsen.

Because of that, most trees are still filled with leaves, which can make them more susceptible to winds — and could lead to a loss of electricity for some.

"We are planning for the likelihood that there would be some outages in our system," said Thomsen.

To be ready for possible outages, City Light recommends putting together an emergency kit with supplies that will last for three days. The kit should include basics like a three-day supply of water and nonperishable food for everyone in the household, a hand-operated flashlight, a hand crank radio and a space blanket, he said.

Seattle Public Utilities (SPU) is attempting to raise awareness about clogged storm drains, which are often a result of weather storms and can lead to excessive flooding. Wednesday it announced the creation of a new Adopt-a-Drain program to encourage people to clear out leaves and dirt from the city's most pesky drains.

Through the program, volunteers can get rakes, gloves and vests, as well as safety training, said program manager Tom Gannon.

SPU utility crews have also stored pumps near Madison Valley, one of Seattle's major flood-prone areas, in case severe weather conditions caused storm drains to clog Thursday, said SPU crew chief Scott Hayden.

The 520 bridge typically gets closed down if there are sustained winds reaching 50 mph for 15 minutes or more, said Lauren Penning, CQ spokeswoman for the state Department of Transportation. A warning siren on the bridge will go off if winds reach 40 mph for one minute.

Penning said bridge crews may decide to close 520 under other criteria if they feel there is a threat to the bridge or to drivers.

The Coast Guard Wednesday warned boaters to be careful on coastal waters of the Pacific Northwest, and reminded them to secure docked boats and make sure loose items are removed.

During the major windstorm last December, sustained winds blew at 45 to 50 mph, with gusts reaching 70 mph. Several people died, and about a million homes lost power. For Thursday's storm, "We're not looking at that order of magnitude," Haner said.

Christina Siderius: csiderius@seattletimes.com