Atmospheric River Impacts Stretch to Eight States

What's New

Impacts from an ongoing atmospheric river that hit the West Coast on Christmas are extending further inland, affecting eight states as of Thursday morning.

Why It Matters

The Pacific Northwest is known for its atmospheric rivers, particularly during the winter months. They bring heavy rain and snow, typically to Oregon, Washington and California. Though the moisture-laden storms can help alleviate drought, they also pose life-threatening risks from mudslides and floods.

As the storms continue moving further into the U.S., they can sometimes bring winter weather-related impacts to interior states like Idaho and Montana.

What To Know

National Weather Service (NWS) meteorologists have issued multiple weather alerts across the Western U.S. as of Thursday morning. Winter storm warnings, winter weather advisories, high wind warnings and some flood-related warnings were affecting eight states.

A National Weather Service map shows the impacts from an atmospheric river extending into the interior U.S. The storm hit the West Coast on Christmas. National Weather Service

The storm's front is pushing onshore in western Oregon, southwest Washington and Northern California, but there is more inclement weather ahead of the storm that is related to the same system.

In total, the states affected by the atmospheric river are Washington, Oregon, California, Idaho, western Montana, western Wyoming, northern Nevada and northern Utah.

Impacts mostly consist of high-elevation snow for the interior states. Most of the winter weather warnings in the interior states will remain in place until Saturday.

What People Are Saying

NWS Weather Prediction Center meteorologist Brian Hurley told Newsweek: The atmospheric river is "definitely moving quickly. It isn't tapping into tropical moisture like some of them do, so it's a pretty transient system."

He added: "It's not comparable to the event back in November." Late last month, a strong atmospheric river hit the West Coast.

The NWS office in Salt Lake City forecast heavy snow totals over the next few days in a winter storm warning: "If you must travel, keep an extra flashlight, food, and water in your vehicle in case of an emergency. Travel could be very difficult at times. Traction law restrictions may be enacted."

The NWS office in Medford, Oregon, warned of possible river flooding in a hydrologic outlook: "A series of wet frontal systems will produce periods of moderate to heavy precipitation tonight through this weekend. Significant rises are expected late this week, but especially Saturday night into early next week." The outlook went on to say that up to 5 inches of rain could fall in the region's west side valleys and up to 10 inches in the mountains and along the coast. More than a foot of rain was possible in the Curry coastal ranges.

What Happens Next

Beginning December 30, Hurley said, the West Coast will have a bit of a break from the nonstop atmospheric rivers that have hit since mid-December. It could be a week or so before another atmospheric river strikes Washington, Oregon or California, he said.