WHAT: River and urban flooding caused by excessive rainfall is possible. Landslides possible in areas of steep terrain, and debris flows possible over recently burned areas.
WHERE: Counties in Oregon: Benton, Clackamas, Clatsop, Columbia, Hood River, Lane, Lincoln, Linn, Marion, Multnomah, Polk, Tillamook, Washington, and Yamhill. Counties in Washington: Clark, Cowlitz, Pacific, Skamania, and Wahkiakum.
WHEN: From 10 AM PST this morning through late Thursday night.
IMPACTS: Excessive runoff may result in flooding of rivers, creeks, streams, and other low-lying and flood-prone locations. Landslides and debris flows are possible during this flood event. 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.
ADDITIONAL DETAILS: - A prolonged atmospheric river is expected to bring periods of heavy rain to northwest Oregon and southwest Washington Monday through Wednesday, with periods of lighter rain continuing Thursday into Friday. This weather system will result in an increased risk for flooding. Forecast rain amounts from 4 AM Monday through 4 AM Thursday range from 4 to 6 inches in the Cowlitz Valley, lower Columbia, Portland/Vancouver metro and northern Willamette Valley, 2 to 4 inches in the central Willamette Valley, and 1.5-2.5 inches in the southern Willamette Valley. Forecast rain amounts reach 6 to 12 inches in the Cascades, Cascade foothills, Coast Range and the coast, except 2-4 inches from Florence to Newport and in areas of higher terrain in Lane County. Rivers draining the coastal mountains and several Willamette Tributaries have a 30 to 60% chance of reaching minor flood stage or higher. The Pudding River at Aurora and Johnson Creek at Sycamore have an 80% chance of reaching minor flood stage or higher. Chances for flooding along the Willamette mainstem remains low at 5-15%. Urban flooding is possible and water on roadways will increase the risk of hydroplaning and car accidents. Landslides in areas of steep terrain will be possible, as well as debris flows over recently burned areas. - http://www.weather.gov/safety/flood
