Washington and Oregon are bracing for major flooding and possible evacuations as an atmospheric river event brings heavy rainfall to an already saturated region.
More than 6 million people are under flood watches in Western Washington through Friday, as well as parts of Idaho and western Montana, with more than 7 inches of rain expected.
Some 18 river locations in Washington are now forecast to experience major flooding.
Washington’s State Emergency Operations Center was activated Tuesday at level 1, its highest response level, Gov. Bob Ferguson said in a statement.
Firefighters have already used inflatable kayaks to rescue people trapped in submerged vehicles.
More than a foot of rain is expected across elevated parts of the Pacific Northwest this week, after persistent and record-breaking rain earlier this week caused by the same atmospheric river. Rainfall at the Olympia Regional Airport reached 3.03 inches on Monday, breaking the previous record of 2.5 inches.
The Skagit River is predicted to crest at more than 47 feet near the town of Concrete, north of Seattle, according to a National Oceanic and Atmospheric Administration gauge — that would be more than 5 inches above the existing record and 15 feet above the threshold for a major flooding event.
People in low-lying parts of Skagit County were told to "prepare for possible evacuation" by the state Emergency Management Division. Authorities were working with the American Red Cross to prepare a shelter for affected families in the eastern part of the county.
The fire department in Lewis County advised residents in flood-prone areas to evacuate while they still could. "Waiting until the rivers are at their highest puts your lives and safety — as well as those of our emergency responders — at risk," it said on Facebook.
The Snohomish River in Washington is set to reach 33.6 feet in the next 48 hours, 12 feet above its normal level, breaking a previous record by a few inches. The Grays River in Washington reached a record-breaking 33.3 feet in Rosburg on Monday.
Snohomish County declared a state of emergency Tuesday because of flooding in multiple rivers, with levels potentially reaching historic levels.
"We’ve made it through the first part of this weather challenge, but the forecasts tell us we need to prepare for another, bigger surge of rain and high water later this week," Snohomish County Emergency Management Director Lucia Schmit said in a statement.
Many roads are covered with water and are impassible. As with flooding events, authorities are urging drivers in affected areas not to drive through floodwaters, especially at night when water depth is harder to judge.
An atmospheric river is a long, narrow band of atmospheric moisture that carries water and delivers heavy precipitation. A major event can discharge more than 15 times the average flow at the mouth of the Mississippi River.
CORRECTION (Dec. 12, 02:24 ET): A previous version of this article misstated the level the River Skagit was forecasted to reach. It was 15 feet, not inches, above the threshold for a major flooding event.
