The cause of Western Oregon's extreme flood events is NOT heavy rain by itself, contrary to popular belief. The most common cause is warm "Pineapple Express" rains following on the heels of major snowstorms in the Cascades, and especially warm, heavy rains following those snowstorms that are cold enough to deposit unusually deep snows in the expansive mountain catchment areas that are between 2000 and 3000 ft. elevation. Under such a combination of conditions, the Pineapple Express rains are then able to create enormous volumes of snowmelt in the course of just a few days, overloading every stream, lake and river's capacity. Below is a very minor Willamette Valley stream raging with brown mud, threatening the foundation of a 100 yr old barn that has stood through many past floods.
Gribble Barn in danger.
Oregon City, along Hwy 99E, just north of I-205 bridge.
Today Mickey-D's drive-thru is "Open for Boat Traffic Only." This McDonald's Restaurant in Gladstone was soon open for business again, and remains open as of 2016, the 1996 flood just a distant memory.