Pacific Northwest Braces for Even More Flooding Rain This Week

Washington and the Pacific Northwest are facing multiple rounds of torrential downpours this week, raising flood risks in the region as residents are still grappling with last week’s historic rains.

Heavy rain was peaking Monday in Washington, where as much as 3 inches (8 centimeters) could fall throughout the day before another system arrives Wednesday followed by a third on Sunday, said Ashton Robinson Cook, a forecaster at the U.S. Weather Prediction Center. The storms stand to drop 7 inches to 10 inches of rain in areas already waterlogged from record flooding that prompted evacuation warnings for more than 100,000 people.

“There could be considerable flood impacts on rivers that are already swollen because there has been so much rain for the past month,” Robinson Cook said. “Western Washington is where the worst of it is.”

The rains are the result of atmospheric rivers, long plumes of moisture coming off the Pacific Ocean that can bring as much water as the amount that flows through the mouth of the Mississippi River. Some areas have already been drenched by more than 16 inches of rain, which has closed major highways and sent rivers over their banks.

Heavy rain is also forecast to sweep into British Columbia. Yellow rainfall warnings have been issued in Vancouver and orange warnings are in place for some regional highways that may be made impassable due to flooding, according to Environment and Climate Change Canada.

Robinson Cook said the situation could be exacerbated if snow falls at higher elevations and combines with rain, creating melt water that adds to the flood threat. Each storm will likely strike different areas, with the second system forecast to hit Oregon and the third moving further south into California.

“There is going to be quite a bit of rain,” he said.

Top photo: Water from the Snohomish River partially submerges homes in Snohomish, Washington on Dec. 12. Bloomberg.