Flood watch in effect through Friday; landslide risk across region

A flood watch is in effect for the Tualatin Valley, the northern Coast Range, and surrounding areas through Friday evening as an atmospheric river moves through northwest Oregon. The National Weather Service issued the watch at 5 p.m. Wednesday. Heavy rainfall could trigger landslides and debris flows in steep terrain, including areas burned by recent wildfires. The flood watch covers a wide swath of the region, including the Portland West Hills and Chehalem Mountain, Clatsop and Tillamook county coasts, the Lower Columbia River corridor, and parts of the Willamette Valley and Columbia River Gorge. The Wilson River near Tillamook was at 7.3 feet Wednesday afternoon, well below its 12-foot flood stage. The Trask River was at 10.2 feet, below its 16.5-foot flood stage. Both are expected to rise as the storm moves through. The Oregon Department of Geology and Mineral Industries warned that debris flows can travel a mile or more and move faster than a person can run. People living below steep slopes, in canyons, or near canyon mouths may be at risk. DOGAMI advised residents in the watch area to track conditions by radio or online, listen for unusual sounds like cracking trees or knocking boulders, and watch for sudden changes in stream water — muddy water or a sudden increase or decrease in flow can signal a debris flow upstream. Drivers should assume roads are not safe during the storm, particularly at night, as roadside embankments may fail. Forest Grove readers should be aware that Fern Hill Road often floods during heavy rains. Visit isfernhillflooded.newsinthegrove.com for more information.