Southwest Washington under flood watch, according to NWS Portland

With rain drenching the area, a swath of western Washington and Oregon are under a flood watch, according to the National Weather Service in Portland.

“We’re entering a period of very active weather with at least two atmospheric rivers on the way, bringing heavy rain, heavy Cascade snow (above 3000 ft), & some river flooding. Dangerous travel over the Cascade passes,” NWS shared on X, formerly Twitter.

As many as three atmospheric rivers are expected to sweep into Southwest Washington and northwest Oregon this weekend and early next week. The heaviest rainfalls are expected Saturday night through Sunday. The Vancouver-Portland area and much of the Interstate 5 corridor can expect 3 to 4 inches of rain, with 4 to 7 inches in the western Columbia River Gorge, Cascades and Cascade foothills.

Excessive runoff may result in flooded rivers, creeks and streams, along with other low-lying and flood-prone areas. Creeks and streams may rise out of their banks. Flooding may occur in streets and urban areas with poor drainage, according to a 5:30 a.m. Friday update from NWS.

“The first system will also bring heavy Cascade snow for elevations above 3,000 feet through Saturday evening,” the agency said in a hydrologic outlook issued Thursday. Snow levels will rapidly rise above 6,000 to 7,000 feet Saturday night. Snowmelt will contribute to river flooding concerns starting Sunday and going into early next week, as rain will be falling over a fresh snowpack.

Most rivers have a 30 percent to 50 percent chance of reaching at least minor flood stage, except the mainstem Columbia and Willamette rivers which have a less than 10 percent chance.

For more information, visit the NWS Portland website.