A collision of weather systems off the coast of California will result in a dynamic storm bringing rain and exceptionally high winds to Sonoma County, starting late Saturday night.
Higher elevations along the coast and in the Mayacamas Mountains will see gusts up to 60 mph, with Mount St. Helena experiencing winds up to 80 mph, said Roger Gass, a National Weather Service Meteorologist based in Monterey.
Rainfall between Saturday night and Monday afternoon will be 2.5 to 3.5 inches in valley locations, and up to 5 inches along the coastal ranges, he said.
A low pressure system dropping out of Alaska is now positioned along the Oregon Coast, said Gass. That system is “going to really draw in a deeper moisture tap that extends all the way to the subtropics.
“It’s basically two systems merging together to create one, and it does have an atmospheric river component to it.”
That merging of systems “typically creates a level of uncertainty in the forecast, as to how exactly they’re going to play out,” Gass added. That uncertainty puts a “question mark” over how much rain the North Bay will get. Gass said he wouldn’t be surprised if rainfall totals exceeded those forecast Saturday afternoon.