Rainfall of up to 8 to 10 inches over the past several days has increased antecedent soil moisture to high levels across western Washington. Additional heavy rainfall of 1 to 4 inches across the lowlands and 4 to 10 inches over the Olympics and Cascades is expected through late Wednesday. Wet and unsettled conditions are also favored to continue through the rest of the week. This amount of rain will put extra pressure on soil instability, leading to an increased threat of landslides and debris flows, especially from recent burned areas.
A mudslide was reported along I-90 Monday evening near North Bend, causing highway closures and extensive delays. More landslides are possible.
Areas most susceptible to landslides debris flows under these conditions are steep coastal bluffs, other steep hillsides or road cuts, and recent burned areas. A diminishing threat of landslides and debris flows will continue for several days after the rain ends.