Short-lived, weak atmospheric river possible in Oregon Friday
A late-season, minor atmospheric river is expected to impact parts of the west coast Friday and into the weekend.
PORTLAND, Ore. (KOIN) -- A late-season, minor atmospheric river is expected to impact parts of the West Coast Friday and into the weekend.
A short-lived atmospheric river will increase rain accumulation across the Portland area and much of western Oregon and Washington starting Friday afternoon. Compared to most winter atmospheric rivers, this one will increase the rain potential, but will be short-lived with little impacts.
Friday's rain timeline
A powerful spring front will swing through the Pacific Northwest Friday afternoon. A dry and sunny start to the day may be deceiving. Clouds will quickly increase across the region Friday morning. Rain showers will increase along the coast during the mid-morning hours. That's where rain will quickly race east. Rain will arrive in and around the greater Portland-Vancouver metro area just after noon.
Widespread, heavy and persistent rain will continue through Friday night and continue through much of the day Saturday. Rain accumulation will amount to nearly two inches along the Willamette Valley through the end of the weekend.
Why is this atmospheric river different than others?
An atmospheric river is a stream of moisture stretching from the state of Hawaii to the west coast. It's that very setup that's expected to bring widespread rain back to the Pacific Northwest for this first weekend in May.
This atmospheric river is much weaker with less rainfall than a typical winter event. The National Weather Service out of Portland explained that this round of rain is only expected to last from six to 12 hours, making it a weak or minor atmospheric river. Meteorologists at The National Weather Service also explained that the impacts felt with this short-lived atmospheric river will be minimal compared to a traditional atmospheric river seen during the winter months.
The wet weather will also keep temperatures below normal by over 10 degrees through the weekend. That's where daytime highs will struggle to warm any greater than the mid 50s. The end of Portland's wet weather saga is expected to come to an end by the end of next week. That's where temperatures are expected to warm and skies will start to dry.