FXUS66 KMTR 040546 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 946 PM PST Tue Dec 3 2024 ...New AVIATION... .SYNOPSIS... Issued at 157 AM PST Tue Dec 3 2024 Above normal temperatures and dry conditions will continue to prevail through the week. && .UPDATE... Issued at 837 PM PST Tue Dec 3 2024 Nearly stationary, strong long wave ridging along the West Coast and a Rex Block (closed 500 mb high north in latitude of a closed 500 mb low) is resulting in above early December normal temperatures and dry weather. Oakland downtown temperature warmed to 70F today, this exceeded the previous record high 67F on this day in 2014, 2011, 2007 and 1979. 8 pm WMC-SFO, SAC-SFO and ACV-SFO pressure gradients are directed offshore at 9.5 mb, 0.3 mb and 2.6 mb respectively. Long wave ridging along the West Coast essentially remains unmovable through the remainder of the week. Above normal temperatures and dry weather will continue through this time. && .SHORT TERM... Issued at 206 PM PST Tue Dec 3 2024 (This evening through Wednesday) Near term - not a lot of change since the morning update. Stratus/fog remains over the coastal waters/Big Sur and alto-cu continues to stream northward over the Central Coast. The upper atmosphere is in a little bit of a traffic jam with a Rex Block vibe. Upper level ridging to the north and low pressure overhead in CA. One weather highlight for today, in addition to the above temperatures, was a potential record high for the Oakland climate site. As of 2 PM, 70 at Oakland DT, which breaks the previous record 67 in 2014. Tonight through Wednesday...no significant weather impacts. As noted earlier not a lot of movement currently in the longwave pattern. Therefore, another mostly clear night expected. Some patchy dense fog possible again over the North Bay valleys and moreso over the Central Valley. Wednesday will feature another day with above normal temperatures, especially away from the coast. Not expecting any records for Wednesday, but Oakland will come close again. Highs will be upper 50s to 60s along the coast and 60 to low 70s inland. && .LONG TERM... Issued at 245 PM PST Tue Dec 3 2024 (Wednesday night through next Monday) Two tools utilized by meteorologists to view longwave pattern development and potential impacts are: WPC Cluster Analysis(grouping of model solutions/uncertainty) and ECMWF Extreme Forecast Index. First, Cluster Analysis for the next week shows pretty high confidence in potential longwave pattern solutions. For the most part, high pressure with above normal temps/dry conditions. This is further supported with the CPC 6-10 and 8-14 outlooks showing the same. While the Rex Block gets "flexed" over CA by a digging low pressure through PacNW it does remain ever so slightly. The passing low occurs late this week and over the weekend. While some precip moves into CA, it does look to stay north of the forecast area or offshore. At a minimum we'll see a drop in temperatures over the weekend and early next week. Over the weekend, the undercutting low from the Rex Block does finally kick east. In its wake and behind the passing PacNW low will be building high pressure. A large area of upper level ridging rebuilds over the West Coast early next week. Dry conditions remain early next week, but temperatures stay cool. Now for the EFI, rather quiet over the next week. The EFI highlights the above normal temperatures both day/night, but not really impactful. One highlight it does show are the winds. The passing disturbance over the PacNW does help bring gusty winds to the coastal waters/northern coast on Sunday. Impacts will be on the marine environment. Looking farther down the road, precip starts to come back into the picture mid-month per ensembles. Stay tuned... && .AVIATION... (06Z TAFS) Issued at 946 PM PST Tue Dec 3 2024 VFR through the TAF period with fog expected to develop at STS overnight. Night Fog currently shows clouds developing off of the coast of the North Bay and along the Monterey Bay coastline but any fog that does develop is not expected to reach MRY or SNS. Fog is currently forecast to develop at STS around 12Z but there remains some potential for fog to develop earlier than that with both current observations already reporting 100% relative humidity at STS and satellite observations showing a decent cloud bank currently forming along the coastline. Fog is expected to remain fairly localized tonight within the Sonoma Valley and isn't anticipated to be widespread. Light, locally variable winds continue with more moderate northwest winds returning tomorrow morning for most sites. Moderate SE drainage winds are possible at SNS overnight before winds shift to out of the NW by the early afternoon hours. Vicinity of SFO...VFR. Light to moderate onshore flow continues through the late evening before winds weaken overnight and become locally variable. Moderate NW winds around 10 knots return tomorrow afternoon and continue into the evening. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...VFR. Light, locally variable winds continue overnight. Satellite shows fog developing over the Monterey coastline but is not expected to impact SNS or MRY. Any fog that does reach either airport should only be temporary in nature. Moderate SE drainage winds are expected at SNS overnight before winds become more northwesterly at both airports during the day. && .MARINE... (Tonight through next Sunday) Issued at 835 PM PST Tue Dec 3 2024 Long period northwest swell, light to moderate north winds, and wave heights between 3 to 7 feet continue through late this week. Winds look to strengthen and seas start to build late this weekend and continuing into next week. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...None. && $$ SHORT TERM...MM LONG TERM....MM AVIATION...Kennedy MARINE...Kennedy Visit us at www.weather.gov/sanfrancisco Follow us on Facebook, Twitter, and YouTube at: www.facebook.com/nwsbayarea www.twitter.com/nwsbayarea www.youtube.com/nwsbayarea