Debris Flow — Coast Range of Nw Oregon, Oregon

2007-12-11 · Coast Range of Nw Oregon, Oregon

Event narrative

A massive debris flow, 10 feet deep and 900 yards wide, holding approximately 40,000 cubic yards of mud and debris, swept over Highway 30 about 8 miles west of Clatskanie only 90 minutes after homes in the area were evacuated. Four homes, several automobiles, boats, and an RV were destroyed.

Wider weather episode

An unusually strong combination of storms brought an extended period of rainfall to northwest Oregon. Accumulations from this recent rainfall in the north Oregon Coast Range were around a foot or more of water, which fell in a relatively short period of time--just over two days. The heavy rainfall, in combination with steep sloped terrain caused a debris flow of rare magnitude. The landslide reportedly traveled at a speed of 30 to 45 mph. This slide engulfed homes in its path and even carried one down with it. The landslide washed over Highway 30, closing the highway to all traffic for about four days.

Source: NOAA Storm Events Database, event_id 72354. Narrative written by the NWS forecast office that issued the report.