239 FXUS66 KMTR 261159 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 459 AM PDT Sat Jul 26 2025 ...New AVIATION, MARINE... .KEY MESSAGES... Updated at 153 AM PDT Sat Jul 26 2025 - Below to near seasonal normal temperatures through Friday. && .SHORT TERM... Issued at 153 AM PDT Sat Jul 26 2025 (Today and tonight) The July 26th 00Z sounding revealed an 850 millibar temperature of 17.15 degrees Celsius, just above the 25th percentile of 17.1 degrees Celsius for this date and time. San Jose (SJCthr) tied its daily (July 25th) low maximum temperature record of 73 degrees Fahrenheit set in 1924. Napa State Hospital (NSHC1) is forecast to tie its daily (July 26th) low maximum temperature record of 70 degrees set in 1935. Needless to say widespread below normal temperatures, a relatively deep marine layer, and drizzle will continue today. The upper-level trough that has been the dictator of our recent weather brings a low probability (5%) high-impact scenario of elevated convection. The essential ingredients for thunderstorms of lift, instability, and moisture are there, but they are not impressive. With very little change to the pattern, it is expected that convection will continue to present itself as it has the previous two days, remaining confined to the north and east of our region. If a thunderstorm were to develop, the primary hazards will be dependent on if they are wet (rainfall greater than or equal to 0.10 inch) or dry (rainfall less than 0.10 inch). Wet thunderstorm hazards will be locally heavy rainfall and gusty outflows while dry thunderstorm hazards will be new fire starts and gusty outflows. && .LONG TERM... Issued at 153 AM PDT Sat Jul 26 2025 (Sunday through Friday) Global ensemble clusters are in agreement of heights rising through Tuesday as broad high pressure expands westward and a longwave ridge is able to form over the Intermountain West. This will result in a slight warming trend with temperatures returning to near normal for valleys and terrain above the marine layer. While it is likely that heights will begin to fall Wednesday as an embedded shortwave from the upper-level low in the Gulf of Alaska traverses the region, sensible weather will fluctuate very little through Friday with the coast remaining cool, the interior remaining mild, and onshore flow prevailing. && .AVIATION... (12Z TAFS) Issued at 440 AM PDT Sat Jul 26 2025 The marine layer is 2,600 ft according to the ascending 12Z weather balloon. With ceilings lower than yesterday, this means a deeper cloud layer and better chance for drizzle through the morning hours. The overall trend today will feature lifting ceilings and/or clearing mid-day, moderate onshore winds in the afternoon, and a return of MVFR-IFR stratus this evening. Vicinity of SFO...MVFR ceilings at SFO and IFR ceilings at OAK will persist through the early morning. There is a decent chance that the ceilings never break at SFO and OAK. The skillful GFSLAMP actually leans that way, but the current satellite shows some holes in the stratus, and the persistence forecast suggests at least a few hours of clearing in the afternoon. As such the TAFs lean optimistic. The confidence is low, especially for OAK. SFO Bridge Approach...The current satellite image shows some clearing over the Bay, though it will likely close before the heavier traffic arrives this morning. Monterey Bay Terminals...MVFR-IFR ceilings with periods of drizzle through the morning at MRY and SNS. Some improvement is expected this afternoon with clearing at SNS and lifting ceilings at MRY. The trickiest part is figuring out if MRY will clear at all today. With boundary layer winds funneling moist air over the Monterey Bay and only a thin layer of dry air above the marine layer, the chances are good that ceilings will linger over parts of the Monterey Peninsula all day. It`s still not clear whether these clouds will remain over the terminal this afternoon or stay confined to the immediate coastline. && .MARINE... (Today through Thursday) Issued at 440 AM PDT Sat Jul 26 2025 Moderate northwest breezes and moderate seas prevail through Tuesday with stronger gusts in the afternoons. Low clouds with drizzle are expected this morning. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...Small Craft Advisory from 3 PM to 9 PM PDT Sunday for Mry Bay- Pigeon Pt to Pt Pinos 0-10 nm-Pt Arena to Pt Reyes 0-10 nm. Small Craft Advisory from 3 PM Sunday to 3 AM PDT Monday for Pt Pinos to Pt Piedras Blancas 0-10 nm. && $$ SHORT TERM...Sarment LONG TERM....Sarment AVIATION...Flynn MARINE...Flynn 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