The National Weather Service has issued a Flood Watch for portions of northwest Washington and west central Washington, including Mason County. The Flood Watch will be in effect from Thursday morning through Saturday morning.
Forecasters say heavy rain in the Olympics and North Cascades Wednesday night and Thursday will cause significant rises on rivers with headwaters in these mountains. Minor flooding is possible on some rivers.
Rain is forecast to be heaviest along the west slopes of the Olympics and over the far north Cascades. With this pattern, the rivers most likely to flood are the Bogachiel in Clallam County, the Nooksack in Whatcom County, and the Skokomish in Mason County.
If rainfall is somewhat heavier than forecast, and spreads over a larger region, other rivers flowing off the Olympics including the Satsop in Grays Harbor County could reach flood stage. The Skagit and Samish Rivers in Skagit County, and the Stillaguamish River in Snohomish County, could also reach flood stage in this scenario.
Any flooding that occurs is likely to be minor and would probably happen Thursday night.