Western Washington Faces Major Flooding as Atmospheric River Arrives

An atmospheric river is approaching Western Washington, bringing a heightened risk of major river flooding and landslides, according to the National Weather Service. The system is expected to deliver substantial rainfall starting Monday, with Seattle projected to receive 2 to 3 inches from Monday through Wednesday. The Cascade Mountains may experience over 5 inches, leading to swollen rivers as water flows downstream to Puget Sound.

The flood forecast intensified on Sunday, with conditions anticipated to change rapidly as rainfall totals fluctuate. As of Sunday evening, several rivers are projected to reach major flood stages:

• The Skykomish River near Gold Bar is expected to crest inches over major flood stage by 10 p.m. Monday, recede Tuesday morning, and approach major flood stage again Wednesday, fully receding by Thursday morning.

• The Puyallup River near Orting is forecast to crest around 10 p.m. Monday, with two additional peaks, potentially nearing a record flow of 21,500 cubic feet per second around 4 a.m. Wednesday.

• The Snoqualmie River at Snoqualmie Falls is anticipated to reach about a foot over major flood stage at 4 a.m. Tuesday, crest again at major flood stage around 4 p.m. Wednesday, and recede by Thursday night.

• The Cowlitz River at Packwood is projected to rise inches over major flood stage around 4 a.m. Tuesday, recede, and rise again to a foot over major stage by 4 a.m. Wednesday.

• The Skagit River near Concrete is expected to be inches over major flood stage by 4 a.m. Tuesday, receding by afternoon.

• The Snohomish River near Snohomish is likely to swell within inches of major flooding from Tuesday afternoon until Friday.

Scott North, spokesperson for the Snohomish County Department of Emergency Management, urged residents in flood-prone communities to prepare for high water starting Monday and lasting into mid-week. He advised vigilance for roads blocked by debris and cautioned against driving through standing water, noting that as little as a foot can float a car.

An atmospheric river is a plume of moisture from the subtropical Pacific Ocean. While most are not dangerous, the current system is expected to bring days of rain and increased risks of flooding and landslides. Winds will increase Monday morning, becoming breezy area-wide by the afternoon and evening, with gusts up to 45 mph around Puget Sound and slightly higher on the Pacific coastline.

Given higher snow levels at 5,000 to 6,000 feet and wet soil conditions, there is an elevated risk for landslides due to heavier rainfall runoff. Sheri Badger, spokesperson for King County’s Office of Emergency Management, stated that officials are working with state and city leaders to prepare for the floods but acknowledged the difficulty in preventing and predicting landslides.