Residents began packing up and fleeing rising rivers in western Washington state Wednesday as a new wave of heavy rain swept into a region still reeling from a storm that triggered rescues and road closures a day earlier.

In the Pacific Northwest, an atmospheric river was swelling rivers toward record levels, with major flooding expected in some areas including the Skagit River, a major agricultural valley north of Seattle. In the town of Mount Vernon, officials ordered residents within the river’s floodplain to evacuate.

Earlier in the day, dozens of vehicles were backed up at a sandbag-filling station in the town as residents prepared for what Mayor Peter Donovan described as “what increasingly appears to be a worst-case scenario here.”

Washington Gov. Bob Ferguson declared a statewide emergency Wednesday, saying, “Lives will be at stake in the coming days.” He estimated that as many as 100,000 Washington residents may soon face evacuation orders.

“We expect rivers to hit historic levels as early as 4 a.m. tomorrow, lasting into Friday morning,” Ferguson wrote on social media.

Ferguson later posted that the National Oceanic and Atmospheric Association’s National Weather Prediction Service had predicted 18 major floods and 15 moderate floods in the state.

The National Weather Service warned of the possibility of “catastrophic flooding,” specifically along the Skagit and Snohomish rivers.

“Landslides are likely in areas of steep terrain within the considerable and catastrophic regions,” the weather service said.

Gent Welsh, adjutant general of the Washington National Guard, said hundreds of Guard members will be sent to help communities.

In the Mount Rainier foothills southeast of Seattle, Pierce County sheriff’s deputies rescued people at an RV park in Orting, including helping one man in a Santa hat wade through waist-deep water. Part of the town was ordered to evacuate over concerns about the Puyallup River’s extremely high levels and upstream levees.

A landslide blocked part of Interstate 90 east of Seattle, with photos from Eastside Fire & Rescue showing vehicles trapped by tree trunks, branches, mud and standing water, including a car rammed into the metal barrier on the side of the road.

Officials also closed a mountainous section of U.S. 2 due to rocks, trees and mud. The state transportation department said there were no detours available and no estimated time for reopening.

The Skagit River is expected to crest at roughly 47 feet in the mountain town of Concrete early Thursday, and roughly 41 feet in Mount Vernon early Friday.

Those are both “record-setting forecasts by several feet,” Skagit County officials said.

Flooding from the river long plagued Mount Vernon, the largest city in the county with some 35,000 residents. In decades past, residents would form sandbagging brigades when floods threatened, but businesses were often inundated. Flooding in 2003 displaced hundreds of people.

The city completed a floodwall in 2018 that helps protect the downtown. It passed a major test in 2021, when the river crested near record levels.

But the city is on high alert. The historic river levels expected Friday could top the wall, and some are worried that older levees could fail.

“The concern about that kind of pressure on the levy and dike system is real,” said Ellen Gamson, executive director of the Mount Vernon Downtown Association. “It could potentially be catastrophic.”

Gamson said many business owners were renting tables to place their inventory higher off the floor. Sheena Wilson, who owns a floral shop downtown, said she stacked sandbags by the doors and cleared items off the floor.

“If the water comes in above table height I’ve got bigger problems than my merchandise,” she said.

Jake Lambly, 45, added sandbags, tested water pumps and moved valuables to the top floor of the home he shares with his 19-year-old son. Lambly said he was concerned about damage in his neighborhood, where people “are just on the cusp of whether or not we can be homeowners.”

“This is my only asset,” he said from his front porch. “I got nothing else.”

Harrison Rademacher, a meteorologist with the weather service in Seattle, described the atmospheric river soaking the region as “a jet stream of moisture” stretching across the Pacific Ocean “with the nozzle pushing right along the coast of Oregon and Washington.”

Authorities in Washington have knocked on doors to warn residents of imminent flooding in certain neighborhoods, and evacuated a mobile home park along the Snohomish River. The city of Snohomish issued an emergency proclamation, while workers in Auburn, south of Seattle, installed temporary flood control barriers along the White River.

In Sumas, a small city along the U.S.-Canada border, a flood siren rang out at city hall and residents were told to leave. The border crossing was also closed to southbound commercial vehicles to leave more room for evacuations, according to the Abbotsford Police Department.

Climate change has been linked to some intense rainfall. Scientists say that without specific study they cannot directly link a single weather event to climate change, but in general it’s responsible for more intense and more frequent extreme storms, droughts, floods and wildfires.

Another storm system is expected to bring more rain starting Sunday, Rademacher said. “The pattern looks pretty unsettled going up to the holidays.”