Atmospheric River That Drenched the Northwest Is Now Supercharging 2 Winter Storms

An atmospheric river brought catastrophic flooding to the Pacific Northwest this week, prompting evacuation orders, major highway closures, and rescue efforts. Meteorologists expect the rain to begin slowing down this afternoon, but there’s plenty more severe weather in the forecast.

The plume of moisture slammed into the region on Tuesday, dumping 5 to more than 10 inches (13 to more than 25 centimeters) of rain over the last several days, according to the National Weather Service. The flooding is most severe in western Washington, where Governor Bob Ferguson has declared a state of emergency and mobilized the National Guard to aid disaster response. As of Wednesday, the state was preparing to evacuate 100,000 residents.

Local news outlets in Oregon reported Wednesday that floodwaters were receding from some areas after the atmospheric river moved north into Washington, and residents were beginning to assess the damage. By Thursday morning, a 24-hour downpour was slowing down in B.C.’s Fraser Valley after triggering evacuations and highway closures and forcing the city of Abbotsford to declare a local state of emergency.

“While the heaviest rainfall is subsiding, lingering rain through Friday will exacerbate ongoing major river flooding, and landslides will continue across portions of western Washington state and northwest Oregon for several days,” the NWS stated in a Thursday update. Indirect impacts from this system could extend across the northern U.S. into next week as it joins forces with two clipper storms and possibly another atmospheric river.

Supercharged clipper storms

Clipper systems are fast-moving winter storms that form near Alberta, Canada, and quickly sweep southeast across the northern United States. They typically produce light snow, but the two on deck this week could bring up to a foot and a half (0.45 meters) to parts of the upper Midwest, Northeast, and Mid-Atlantic by the weekend, The New York Times reports.

That’s because the atmospheric river currently affecting the Pacific Northwest is sending moisture into the upper atmosphere that will amplify precipitation from storms further east, NWS meteorologist Brian Hurley told the Times.

Parts of 15 states from Montana to Vermont and as far south as Virginia were under winter weather advisories Thursday as the first of these two systems treks eastward. The second clipper storm will follow close behind, spreading snow from the northern High Plains into the Ohio Valley by Thursday and reaching the central Appalachians early Friday.

As it moves into the Northeast over the weekend, there’s a chance that New York City, Boston, and Philadelphia could see their first significant snowfalls of the season.

Another atmospheric river on the way

The atmospheric river hitting the Pacific Northwest this week will join forces with a new one early next week and hit again. pic.twitter.com/ILuWqEaVyb

— Ben Noll (@BenNollWeather) December 11, 2025

The core of the atmospheric river should move into B.C. by Friday, meteorologist Ben Noll reports for The Washington Post. This should give Washington a break from the rain, but Noll expects a resurgence of precipitation from Sunday into early next week.

“The atmospheric river hitting the Pacific Northwest this week will join forces with a new one early next week and hit again,” he posted on X Thursday morning.

This won’t give communities much time to recover from this week’s weather, as the risk of flooding returns. Research has shown that back-to-back atmospheric river landfalls are becoming more common on the West Coast as the global temperature rises, underscoring the urgent need for adaptation and resilience strategies.

With flood risk lingering in the Pacific Northwest and supercharged snowstorms heading east, it appears winter is already off to a wild start. Keep an eye on the forecast as this complex mix of weather systems develops over the next several days.