A storm more commonly seen in winter is approaching Washington and will hit the state by the end of the weekend.
This winter, the West Coast faced a slew of atmospheric rivers that caused devastating floods and landslides. The storms also brought a deluge of rain that supplemented California lakes and rivers, helping eliminate the state's drought.
Atmospheric rivers are 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. In the United States, the moisture-laden storms typically are seen during the West Coast wet season over the winter.
The National Weather Service (NWS) office in Seattle warned that despite summer's approach, an atmospheric river-style system is expected to bring foul weather to western Washington this weekend.
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"A late season atmospheric river-style system will bring moderate to heavy rain across western Washington Sunday into Tuesday," the NWS office posted on X, formerly Twitter, on Thursday. "Take time now to prepare for possible heavy rain, and continue to monitor for further updates with this system."
NWS meteorologist Trent Davis told Newsweek that late-season low-pressure centers are moving into the Pacific Northwest, funneling a "train of moisture from the subtropics." He said the heaviest rainfall will occur Sunday night into Monday and added that the system is uncommon for this time of year.
"It's a little late in the season," he said. "They can happen, but they tend to be late fall to mid-winter."
As of Friday morning, there was no weather warning in place in Washington regarding the storm. Meteorologists had issued a hydrologic outlook, however.
"A late season atmospheric river will bring moderate to heavy precipitation from Sunday afternoon through Tuesday across all of western Washington," the outlook said. "Heavy rainfall rates are possible over the southwest Olympics, and the Cascades. Total rainfall amounts will range from 1 to 2 inches in the lowlands, and 2 to 4 inches in the mountains."
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The outlook said that snow is unlikely with this storm given that snow levels will remain above 5,000 feet. However, the excessive rain could cause rivers in the area to run unusually high, "with the Skagit, Snohomish, Skykomish, White, and Skokomish Rivers potentially over action stage."
"The Snoqualmie River potentially will reach minor flood stage," the outlook said. "This may impact any use of the river flood planes that are normally dry this time of year. Rivers will crest sometime between Sunday and Tuesday."
According to the NWS Seattle precipitation forecast, Forks, Washington, has the highest chance of seeing greater than 2 inches of rain from the storm. Most regions impacted by the storm will see more than .25 inches, the forecast said. Quillayute also has a higher chance of seeing more than 2 inches.
Davis said the biggest impact will be river flooding. There also could be agriculture and travel disruptions.
About the writer
Anna Skinner is a Newsweek senior reporter based in Indianapolis. Her focus is reporting on the climate, environment and weather ... Read more
