On Sunday at 1:29 p.m. a hydrologic outlook was issued for Clatsop County Coast, Tillamook County Coast, Central Coast of Oregon, North Oregon Coast Range Lowlands, Central Oregon Coast Range Lowlands, North Oregon Coast Range, Central Oregon Coast Range, Lower Columbia River, Tualatin Valley, West Hills and Chehalem Mountains, Inner Portland Metro, East Portland Metro, Outer Southeast Portland Metro, West Central Willamette Valley, East Central Willamette Valley, Benton County Lowlands, Linn County Lowlands, Lane County Lowlands, West Columbia River Gorge of Oregon above 500 ft, West Columbia River Gorge I-84 Corridor, Upper Hood River Valley, Central Columbia River Gorge I-84 Corridor, Clackamas County Cascade Foothills, Cascade Foothills of Marion and Linn counties and Lane County Cascade Foothills.

"A series of storms will bring ample precipitation to Northwest Oregon and Southwest Washington this week. Of particular concern is the potential for heavy rain Tuesday night through Friday morning, which could result in some flooding for area creeks and rivers. The latest projections of the most likely amounts for storm total precipitation are a little lower today than yesterday's forecasts. Amounts range from 3.5 to 6 inches for the Coast, Coast Range, and Cascades, with 1.5 to 3 inches for inland valley locations, including Portland, Salem, and Eugene. Upper end projections, with about a 10 percent chance of occurring, range from 6 to 10 inches for the Coast, Coast Range, and Cascades, and 2.5 to 3.5 inches for inland valleys. Snowmelt in the Cascades from 2000 to 4000 feet elevation could add runoff, although runoff from heavy rain would be the main driver for any flooding that occurs. Rivers will rise starting Wednesday. Small streams and fast-responding rivers could see flooding as early as Wednesday night or Thursday, with slow-responding rivers potentially flooding by this weekend. Heavy rainfall will also cause water ponding in low-lying areas and other areas of poor drainage," according to the National Weather Service.

News Source : https://www.oregonlive.com/weather-alerts/2024/11/hydrologic-outlook-affecting-oregon.html