Map Shows Cities Most at Risk as Atmospheric River Hits US

Several cities in the Pacific Northwest are at a heightened risk for flooding as an atmospheric river pummels the region with excessive rain.

The ongoing storm has saturated much of the Pacific Northwest since it arrived over the weekend. An atmospheric river is a "long, narrow region in the atmosphere—like rivers in the sky— that transport most of the water vapor outside of the tropics," according to the National Oceanic and Atmospheric Administration (NOAA). More than a dozen similar storms battered California last winter, and although the deluge alleviated much of the state's drought, it also wreaked havoc through flooding and mudslides.

The most recent atmospheric river has unleashed substantial rain and snow across multiple states thus far, and more precipitation is expected to fall before the storm ends. On Monday, the NWS warned that the atmospheric river is expected to continue until mid-week.

A new map published by the Weather Channel revealed that cities such as Portland, Oregon; Eugene, Oregon; Seattle, Washington, and several other areas were at risk for up to 12 inches of rain through Sunday. Eureka and Crescent City in northwest California also could face a few inches of rain, according to the map.

"Flood concerns increase in the Pacific Northwest as powerful atmospheric river storms unleash a deluge of rain and mountain snowmelt across the region," the Weather Channel posted with the map on X, formerly Twitter, Monday afternoon.

The region has already received heavy rain, and even more could prove hazardous, AccuWeather senior meteorologist Tom Kines told Newsweek.

"There's a flood risk now, and that flood risk will continue for at least a few more days," he said.

So far, Oregon has been hardest hit by the storm. Eugene, Oregon, has received 3.5 inches of rain, and Portland has received more than 2.5 inches, Kines said.

"Those are two cities that stand out as far as receiving the most rain over the past few days, and there's more rain on the rise here," Kines said.

Rain shifted northward toward Washington on Monday, and areas like Seattle and Tacoma saw an influx of precipitation.

A flood watch has been issued across much of western Washington, KIRO 7 reported, and will remain in place through Wednesday. More rain will arrive in Oregon later this week.

The atmospheric river could be indicative of similar storms to come later this winter because of El Niño.

El Niño, one of two climate patterns greatly influencing Earth's weather, is known for its above-average precipitation. The climate pattern began in June following La Niña's culmination. The National Oceanic and Atmospheric Administration (NOAA) has predicted that this year's El Niño has high odds of being historically strong.

However, El Niño doesn't guarantee excessive moisture, as the climate patterns don't always follow predictions. For example, last year was a La Niña year, making the wet winter along the west coast an anomaly.