Residents in western Washington began evacuating Wednesday as an atmospheric river brought heavy rains, swelling rivers toward record levels and threatening catastrophic flooding.

The Skagit River, which runs through Mount Vernon and the agricultural valley north of Seattle, is expected to crest at 47 feet in Concrete Thursday and 41 feet in Mount Vernon Friday, potentially surpassing floodwalls and levees.

Washington Gov. Bob Ferguson declared a statewide emergency, warning that up to 100,000 residents could face evacuation orders, while the National Weather Service forecast 18 major and 15 moderate floods statewide.

Hundreds of Washington National Guard members were deployed to assist, and authorities closed portions of U.S. 2 and Interstate 90 due to landslides and debris, CBS News has reported.

Residents and businesses stocked sandbags, moved belongings to higher ground, and braced for additional storms expected later in the week.