🔗 Share this article

Dangerous rising waters from historically swollen rivers in the Pacific north-west presented a significant danger on the end of the week, with 100,000 people under evacuation warnings and more deluges expected on Sunday.

Heavy Downpours Triggers Extensive Inundation

Torrential rain on the previous day triggered flooding across much of the region from Oregon north through Washington state and into the Canadian province of BC, closing dozens of roads and prompting the evacuations of tens of thousands of people.

The heavy rainfall started several days prior, carried into the area by a weather phenomenon known as an atmospheric river, a huge plume of water vapor channeled from the ocean from the Pacific.

The governor of Washington declared a state of emergency on mid-week in due to the heavy weather that has triggered landslides and washed out roads and submerged vehicles.

Western Washington Takes the Hardest Hit

The western portion of Washington felt the greatest impact of the storm, with flood warnings in effect across the mountain ranges and the Puget Sound area, as well as for a northern section of Oregon. This area is populated by some 5.8 million people.

The identical weather pattern delivered intense rains and inundation to the western part of Montana and an edge of north Idaho.

Orders to Leave and Life-Saving Operations

Approximately 100,000 residents in west Washington on Friday were under level 3 evacuation orders, instructing them to immediately move to safer elevation. The bulk of them were in rural Skagit county north of the city.

An estimated 3,800 displaced persons were thought to be in requiring emergency housing.

First responders have rescued several people, including by helicopter in King and Whatcom counties in recent days.

Damage to Roads and Rail

The worst flooding was reported along the Skagit, Snohomish and Puyallup rivers. More than 30 highways and dozens of smaller roads were closed due to flooding across the region.

Several lengthy segments of a major freight line in the region were washed out or out of service due to flooding, with rainfall totals of 25 to 43 centimeters or more in many areas.

Some rivers have been cresting several feet above record levels and on Friday morning had not receded.

Forecast and Regional Effects

The prediction is for lighter rain on the day and a largely clear Saturday, but meteorologists predict more heavy rain on the weekend for the region.

To the north, in British Columbia, five of the six Canadian highways leading to the coastal city of Vancouver, BC were closed due to floods, rockfalls and the avalanche danger.

"This situation is evolving and extremely fluid," stated the transport ministry.

Access to Vancouver depends heavily on a constrained road and railway network that traverses the Rocky Mountains.

Climate Context

While these types of weather events are not uncommon on the US Pacific coast, experts say they are likely to become more frequent and more extreme in the future if global heating from human-caused factors persists at current rates.