727 FXUS66 KMTR 081936 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 1236 PM PDT Tue Jul 8 2025 ...New SHORT TERM, LONG TERM... .KEY MESSAGES... Updated at 1200 PM PDT Tue Jul 8 2025 - A warming trend will bring minor to moderate HeatRisk for inland and higher elevations Thursday - Friday. - Localized elevated fire weather conditions starting Wednesday across the higher elevations. && .SHORT TERM... Issued at 1200 PM PDT Tue Jul 8 2025 (This evening through Wednesday) The marine layer is currently between 2,200 and 2,700 feet as weak low pressure remains offshore. This system will gradually move inland over the next 36 hours while weakening. Meanwhile, its previous position offshore will be replaced by ridging from subtropical high pressure in the Eastern Pacific. This pattern change will cause the marine layer to compress while onshore NW winds increase. All this means that temperatures will begin to increase starting Wednesday. Highs are forecast to be around 5-10 degrees warmer than today for inland areas. While becoming more shallow, the marine layer will continue to keep coastal areas in the 60s. && .LONG TERM... Issued at 1200 PM PDT Tue Jul 8 2025 (Wednesday night through next Monday) The warming trend will continue into Thursday as the synoptic high pressure becomes more established offshore. For inland areas, this will cause another 5-10 degree jump in temperatures from Wednesday. Some interior and high elevation areas will experience moderate HeatRisk from Thursday - Friday with afternoon temperatures in the 90s. A very weak mid-level disturbance will bring some relief over the weekend, but broadly speaking the pattern looks fairly stable through at least early next week. There will be a very broad area of high pressure across the Northeast Pacific, with an embedded mesoscale high sitting over the Channel Islands. While ensembles are confident that the persistent high pressure will increase the 850 mb temperature to around 24C (90th percentile) by Saturday, this pattern supports steady onshore wind. With ocean temperatures cooler than normal (54F), the marine layer should continue to keep coastal areas seasonably cool, even while the Central Valley flirts with triple digit heat throughout the long term forecast. There is some elevated fire weather concerns above and inland of the marine layer`s influence. The RH will drop below 30% at times, and afternoon wind gusts will reach up to 30 mph. Fortunately with onshore winds, these conditions will be diurnally driven with lighter winds and good humidity recovery in the foothills expected each night. && .AVIATION... (18Z TAFS) Issued at 946 AM PDT Tue Jul 8 2025 Currently a mixed bag of VFR-MVFR at the terminals with an early improvement to VFR on tap. The marine layer is currently being observed at 2,600 feet on the Fort Ord profiler. Just what happens to it over the next 24-30 hours will be heavily dependent on the upper-level pattern as broad upper-level ridging builds in from the Desert Southwest while an upper-level trough swings through Northern California, likely leading in a deepening marine layer from south to north. For now greatest confidence is in widespread low-end MVFR with the possibility for IFR ceilings, particularly at the coastal terminals of HAF, MRY, and SNS. Vicinity of SFO...Currently VFR with northeasterly flow. Westerly flow will begin to prevail this afternoon once the sea breeze kicks in. Moderate to high confidence on the return of sub-VFR ceilings to the terminal tonight with ceilings likely being on the cusp of low- end MVFR to IFR. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...Currently MVFR and calm at both terminals with high confidence in VFR being achieved shortly based on satellite trends. Moderate to high confidence on the return of sub- VFR ceilings to the terminals tonight. Uncertainty resides in the ceiling height due to the fact that the terminals will likely begin to be affected by the upper-level ridge which would subsequently result in subsidence aloft, a compressed marine layer, and thus relatively lower ceilings and visibilities. The key will be on if this can happen tomorrow morning instead of tomorrow afternoon, if so it is reasonable to believe that the terminals may be in the LIFR- IFR category instead of low-end MVFR. && .MARINE... (Today through Sunday) Issued at 926 AM PDT Tue Jul 8 2025 A gentle southerly breeze and moderate seas will prevail today. Winds will strengthen and veer to become moderate and northerly by Wednesday with further strengthening to become fresh to strong on Thursday and into the weekend. Significant wave heights will be rough to very rough Thursday through Saturday for the outer waters. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...Small Craft Advisory from 3 PM Wednesday to 3 AM PDT Thursday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0- 10 nm-Pt Arena to Pt Reyes 10-60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm. && $$ SHORT TERM...Flynn LONG TERM....Flynn AVIATION...Sarment MARINE...Sarment 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