The San Francisco Bay Area and Central Coast are currently under a Red Flag Warning through 5 PM Saturday due to the elevated risk of wildfires sparked by dry conditions and strong winds. According to the National Weather Service San Francisco, this warning excludes coastal Marin, Monterey, and Sonoma counties, where conditions may not be as severe.
A Wind Advisory is also in effect for the North Bay Interior Mountains until 8 AM Saturday, with conditions expected to be less windy but still dangerous for fire spread. "While winds are forecast to decrease through the day, they will continue to prevail out of the northeast, promoting compressional warming and rapid drying," stated the Area Forecast Discussion issued by the NWS. Relative humidity levels as low as 11% have been recorded, along with wind gusts peaking at 76 mph near Mt. St. Helena. Despite a decrease in wind speeds throughout the day, the NWS warns, "Do not let lower wind speeds fool you into thinking that the fire weather threat is over."
Looking ahead, the offshore pressure gradient is projected to weaken and reverse as the current low-pressure system moves out, bringing a warmup of 10-20 degrees above normal by Wednesday. A new low-pressure system expected later in the week could bring a chance of much-needed rainfall, with up to a 40% possibility in the Bay Area, as indicated by the Area Forecast Discussion.
In marine news, gusty northwest winds will persist this morning over certain waters, with some gale-force gusts in the northern outer waters, says the NWS. VFR conditions are expected to continue on the aviation front, but with LLWS concerns diminishing by mid-morning and light offshore flow returning in the evening. "Vicinity of SFO... VFR through the TAF period," noted the NWS in their recent update. However, the major emphasis remains on preventing wildfires, with clear messaging from the NWS: "Every precaution should be taken to prevent a wildfire spark always, but especially today."
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