The National Weather Service in Portland has issued a Flood Warning for Pudding River at Aurora affecting Clackamas and Marion Counties from today through Wednesday morning.
A complex area of low pressure offshore will maintain mild and moist southwest flow into the region through Sunday morning. This will bring rain, heavy at times, to northwest Oregon and southwest Washington. Rainfall of 1 to 3 inches is expected across the region, with 2 to 5 inches over the Willapa Hills, Coast Range and the south Washington Cascades through Sunday morning. Snow levels will be rising Friday, and hover at 7000 to 8000 feet through the weekend. Rain tapers off Sunday into Monday.
With all this rain, and snowmelt from the Coast Range and Cascades, rivers will be rising. Many small streams and creeks will be running high into Sunday. Heavy rainfall will cause water ponding in low lying areas and other areas of poor drainage.
In addition to hydrologic impacts, there may also be an elevated landslide risk. These particularly affects those areas that have seen significant tree damage due to then recent and strong east winds.