974 FXUS66 KMTR 070246 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 746 PM PDT Sun Jul 6 2025 ...New UPDATE... .KEY MESSAGES... Updated at 129 PM PDT Sun Jul 6 2025 - Moderate HeatRisk returns to portions of the Interior Bay Area and Central Coast Wednesday through next weekend. - Localized elevated fire weather conditions for the Bay Area and Central Coast Wednesday through next weekend. - Slight risk (20%-40%) of extreme heat for far interior portions of the Bay Area and Central Coast July 12th-14th. && .UPDATE... Issued at 715 PM PDT Sun Jul 6 2025 The marine layer stratus is beginning its nocturnal push inland as the sun begins to set. By morning, the coverage should be slightly more expansive than today as low pressure offshore allows the marine layer to deepen. Cool and moist will be the theme through Tuesday before a ridge builds and brings inland temperatures above normal Wed-Fri. Thursday looks like the warmest day, but with temperatures about 5 degrees above normal, we are only expecting moderate HeatRisk in inland and higher elevation areas within the North Bay, East Bay, South Bay and Monterey and San Benito Counties. A cooling trend should bring temps back to normal this weekend. && .SHORT TERM... Issued at 129 PM PDT Sun Jul 6 2025 (This evening through Tuesday) An upper-level cutoff low off the Northern California Coast will be the defining feature of the short term forecast. Sensible weather will feature seasonably cool conditions and onshore winds with gusts up to 35 mph through gaps and passes, across ridgelines, and down the Salinas Valley. The marine layer is currently being observed at 1,800 feet on the Fort Ord profiler and will continue to deepen to 3,000 feet by Tuesday. This, in addition to the stratus presentation currently, means that it will have no problem penetrating farther inland tonight and continuing that trend tomorrow night. There is also a slight (15%) chance for drizzle along the coast and over the waters due to the lifting mechanism in place. Southerly transport winds may (you guessed it) transport smoke in from the Madre Fire that is burning in San Luis Obispo through Tuesday. && .LONG TERM... Issued at 129 PM PDT Sun Jul 6 2025 (Wednesday through next Saturday) The pattern begins to change Wednesday as the upper-level cutoff low becomes an open wave and gets nudged eastward by building broad high pressure. This will kickoff the warming and drying trend with the return of moderate HeatRisk and localized elevated fire weather conditions. Fortunately, several rounds of upper-level shortwave trough energy will help keep the ridge in check, not allowing the axis or peak to enter our area. Global ensemble clusters are in agreement with heights rising through Thursday with the ridge showing signs of weakening, albeit slightly, Friday. This will translate to Thursday being the warmest day of the week with temperatures topping out at 10 degrees above normal with Friday being slightly cooler. Global ensemble clusters diverge Saturday with 51% in favor of heights rebuilding and 49% in favor of heights falling, suggesting uncertainty in the forecast. The propagation of what happens will be integral in the extended forecast as the Climate Prediction Center (CPC) has highlighted the far interior portions of the Bay Area and Central Coast with a slight (20%-40%) chance of extreme heat July 12th-14th, thus it is intuitive to believe that if the ridge has more time to build that we could be dealing with hotter conditions and subsequently greater impacts than what are currently being forecast. In terms of elevated fire weather conditions, high pressure and the accompanying subsidence aloft will compress the marine layer to 1,000 feet Wednesday resulting in little inland intrusion and poor to moderate relative humidity recovery above it. Additionally, light offshore flow is expected in the higher terrain during the morning hours of Wednesday and Thursday. Please exercise fire and heat safety, especially coming off of a cool June. && .AVIATION... (00Z TAFS) Issued at 446 PM PDT Sun Jul 6 2025 High confidence for an early return of stratus tonight filling into the coastal valleys and lowering early Monday morning. Low clouds that do develop by Monday morning will likely scatter out and/or clear by Monday afternoon, with the exception of immediate coastal locations. Vicinity of SFO...Medium confidence for MVFR ceilings to return late tonight and potentially lowering to IFR at times early Monday morning. Stratus is forecast to scatter out between 16Z-17Z Monday morning giving way to VFR through the afternoon SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...High confidence for IFR/MVFR ceilings to return this evening and lower to LIFR at times early Monday morning. Also high confidence in clearing to VFR at more inland sites like KSNS, but lower confidence along the coast and around KMRY. && .MARINE... (Today through Friday) Issued at 1048 AM PDT Sun Jul 6 2025 Fresh northwesterly breezes will continue today for the outer waters and coastal jet regions of Point Reyes and Point Sur. Winds gradually begin to slack Monday with moderate to fresh breezes forecast through Wednesday with a surface low positioned over the outer waters. Northwesterly winds increase and significant wave heights build beginning late in the week. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...None. && $$ SHORT TERM...Sarment LONG TERM....Sarment AVIATION...Behringer MARINE...RGass Visit us at www.weather.gov/sanfrancisco Follow us on Facebook, X, and YouTube at: www.facebook.com/nwsbayarea x.com/nwsbayarea www.youtube.com/nwsbayarea |