An atmospheric river that developed in the Pacific Ocean on Tuesday is forecast to take aim at the Pacific Northwest through Thursday night, bringing possible heavy rain and minor flooding, according to the National Weather Service in Seattle.


Atmospheric rivers are long, narrow regions 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. These columns of vapor move with the weather, carrying an amount of water vapor roughly equivalent to the average flow of water at the mouth of the Mississippi River.

According to the Seattle weather service, the Puget Sound region will get a “good shot of rain” with the possibility of 2 to 3 inches total between Wednesday night and Thursday in most areas. Other areas, including over the Olympics and North Cascades, will possibly see up to 5 inches of rain.

Friday is expected to remain drizzly, but the region could get dry weather on Saturday and Sunday before rain returns Monday and Tuesday, according to Matthew Cullen of the weather service in Seattle.

The incoming atmospheric river of rain, and sure signs that the rainy season is upon us, unleashed an unofficial haiku showdown among West Coast National Weather Service branches and other weather poetry aficionados.

“Cloudy and rainy
Pacific Northwest rain train
It must be Fall now,” the Spokane branch tweeted to start the showdown.

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“Stealing our old schtick eh?” NWS Seattle replied. “All right, challenge accepted!”

“Winds blow and rains come
Wet socks and no more dog walks
Fall in Washington,” the Seattle branch wrote.

Additional Washington branches shared more haikus, as well as NWS branches in Oregon, Idaho and California.

Are you ready to show off your rainy weather poetry chops? Send your own weather haikus to morningbrief@seattletimes.com, and we’ll share some of our favorites soon.