Skip to main content
An atmospheric river is coming to town, and here’s what it promises to bring Portland: urban flooding, landslides, and downed trees taking out power lines.
That’s the warning from the Portland office of the National Weather Service, which has issued a flood watch for every county west of the Cascades as a firehose of rain driving inland from the Pacific Ocean takes aim at Northwest Oregon. The atmospheric river—a meteorological term of art with which Oregonians have gained a close acquaintance—begins Monday, eases Tuesday morning, then resumes Tuesday night through Thursday.
National Weather Service meteorologists expect “the first slug of moisture” on Monday to drop about 2 inches of rain, and the second round to bring up to 5 inches.
The result of the deluge? “Saturated soils will see persistent rain and eventually gusty winds, resulting in downed trees and possibly power outages,” the latest NWS forecast says.
While forecasts don’t call for the Willamette River to flood its banks, NWS says there’s a 70% chance that Johnson Creek in outer Southeast Portland will reach a moderate flood stage, and a 60% chance that it will reach major flooding—which would mean Portlanders should “expect widespread flooding of residential and commercial areas along Johnson Creek.”
The risks aren’t just in the floodplains.
“Periods of heavy rain will also increase the risk for landslides in areas of steep terrain and debris flows over recently burned areas. 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.”
And for those of you who really need something to worry about while drying out your socks, there’s the worst-case scenario: a 10% chance that the Portland area gets 8.5 inches of rain over the next four days, and major rivers overflow.
Read the full forecast here.
