The National Weather Service (NWS) in San Francisco has sounded the alarm for potential critical fire weather commencing this Thursday through Saturday, with a Fire Weather Watch already in place. According to the NWS's latest synopsis, an "inside slider event" is expected to usher in not just critical fire weather conditions but also a notable change in the pattern, with a troughing from a deep upper-level low in Canada introducing a cold front into the Bay Area.
While initial conditions involve near-normal temperatures and a shallow marine layer, this trend is set to shift tonight, laying the groundwork for heightened fire weather concerns. Despite expectations of not more than 0.05 inches of precipitation, "this will do nothing to damper the critical fire weather conditions expected beginning Thursday," the National Weather Service specifies. A particular cause for alert is the predicted northerly winds, which as they turn northeasterly/offshore, present the risk of rapid drying and compressional warming.
Strengthening the cause for concern, the NWSBayArea's X post indicates offshore winds of 20-30 mph with gusts up to 40 mph and isolated gusts reaching 50 mph over higher terrain and ridgetops. Daytime relative humidity levels could plunge as low as 15 percent, further exacerbating the fire danger during this period.
Offshore winds of 20-30 mph with gusts to 40 mph, isolated gusts to 50 mph across the highest terrain and ridgetops in tandem with daytime relative humidity as low as 15% will result in critical fire weather conditions Thursday - Saturday. #CAwx pic.twitter.com/fUw2ox0Cmg
— NWS Bay Area 🌉 (@NWSBayArea) October 15, 2024
Not limited to terrestrial implications, the marine forecast details "Rough to very rough seas" continuing across exposed waters due to a long period NW swell — prompting a Small Craft Advisory. Though Thursday may bring a respite, marine conditions are expected to worsen again with the advent of the stronger system. Inland, the windiest conditions are slated for Thursday night into Friday morning and again from Friday night into Saturday morning, as the National Weather Service cites northerly winds on the order of 20-30 mph with possible gusts to 40 mph and even isolated gusts to 50 mph over the most exposed locales.
On the coast, an earlier Beach Hazards Statement remains effective through Wednesday evening, warning of a moderate risk of sneaker waves. The NWS advises beachgoers to maintain vigilance, suggesting an observation period of the ocean for at least 20 minutes before relaxing near the water to ensure safety against sudden large waves.
