5:30 a.m. Winds pose biggest threat for Napa County fire zone: Continued gusty winds, low humidity and higher temperatures threaten to exacerbate already extreme fire conditions in wildfire zones, the National Weather Service warned ahead of a new batch of Red Flag warnings for the North Bay mountains, East Bay hills and Diablo Range.
Expected north to northeast winds of 20 mph could kick up 60 mph gusts at the highest peaks, according to forecasters. The strongest winds forecast for Friday will be in Napa County, where the monster Atlas Fire encroaching on Solano County has burned 43,762 acres and is just 7 percent contained. The deadliest of the fires, Sonoma County's 34,770-acre Tubbs fire, has also burned through a part of Napa County.
”I would keep my eye on Napa Valley," said Drew Peterson, a meteorologist with the weather service. ”That's where the most critical fire weather danger is."
In Sonoma County, Santa Rosa could be threatened by warm, dry Chinook winds — caused when a sloping air mass that travels downhill becomes warm and compressed — which could lead to increased wind speeds. Such winds were a driving factor for fanning flames and rapid growth throughout the wildfires, Peterson said.
The weather service also issued a wind advisory for the North Bay and East Bay hills as winds may topple trees and down power lines.
”It's just going to be all-around poor conditions for fire weather," Peterson said Friday. ”The good news is after this event it looks like the conditions are going to be improving through the area, as far as fire weather goes. The winds are going to be subsiding after Saturday."