Residents in the Pacific Northwest of the US and Canada are bracing for what could be record setting floods as an atmospheric river dumps heavy rain on already swollen rivers.

The US National Weather Service warns that catastrophic flooding is possible in the states of Oregon and Washington along the Skagit and Snohomish rivers.

In Canada, major highways to Vancouver have been closed because of flooding, debris, and the risk of avalanches.

There are evacuation orders in place for thousands of people in the US and Canada, and authorities have warned that more rain is on the way on Thursday.

In the US, the governor of Washington state, Bob Ferguson, declared a statewide emergency on Wednesday, estimating that 100,000 residents could soon face evacuation orders.

The emergency declaration warned that continued rain and snow at mountain elevations would exacerbate flooding conditions, severely impacting supply chains and transportation.

Skagit County, a major agricultural area north of Seattle, has issued an immediate evacuation order to residents who live on the floodplain, with approximately 75,000 people expected to be evacuated.

Across the border in Canada's British Columbia, urgent evacuation orders are also in place for communities including Tulameen and Eastgate, affecting over 371 properties in Abbotsford.

The entire region has been affected by torrential rain from an atmospheric river, a meteorological phenomenon that causes intense storms.

While the heaviest rainfall is expected to ease by Thursday afternoon, authorities warn that lingering water levels in rivers will continue to pose a threat, with further storm systems predicted this Sunday.

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