The promised atmospheric river had arrived in Portland by Monday morning, and that meant: Rain.
According to the National Weather Service, the “strong” atmospheric river would bring rain to much of western Washington and parts of northwest Oregon through Wednesday.
Much of the area is under a flood watch.
“Widespread river, small stream, and urban flooding is likely to occur,” the agency warned in a bulletin. “People, structures, and roads located below steep slopes, in canyons, and near the mouths of canyons may be at serious risk from rapidly moving landslides or debris flows.”
Small streams and creeks in the Portland area have a good chance of flooding, the agency said.
The rain is expected to continue at pace.
Between 1 a.m. and 9 a.m. on Tuesday morning, the National Weather Service said, there is a 70-80% chance that the rain will come down at or above a quarter of an inch an hour, “with probabilities even higher at the coast, coastal mountains, and in the Cascades.
The National Weather Service releases maps showing the likelihood of over 4 inches of rain over the next three days and the likelihood of over 6 inches of rain over the next three days.
The 72-hour probability to exceed 4 inches of rainfall through Thursday, Dec. 11, 2025, in Oregon and Washington.Courtesy of NOAAThe 72-hour probability to exceed 6 inches of rainfall through Thursday, Dec. 11, 2025, in Oregon and Washington.Courtesy of NOAA
The atmospheric river is unlikely to bring snow, even to the mountains, where the snow level is expected to stay around 8,000 feet.
