FXUS66 KMTR 091850 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 1050 AM PST Thu Jan 9 2025 ...New UPDATE... .SYNOPSIS... Issued at 1209 AM PST Thu Jan 9 2025 Gusty conditions this afternoon isolated to the ridgetops of the interior North Bay. Quiet weather Friday with returning offshore winds Saturday into early next week. && .UPDATE... Issued at 1050 AM PST Thu Jan 9 2025 Morning satellite imagery shows blue bird skies across the forecast area this morning. Why? Large scale offshore flow persists. SFO-WMC still over -10mb, which is still pretty decent. Higher peaks around the N and E Bay show gusts of 30-40 mph with Mt St Helena still ripping at 55-65 mph. Thankfully, the winds are not mixing to the surface/valley. Profilers are showing strong winds at 2,000 feet and they're having a hard time making it through the AM inversions. For this afternoon, offshore gradient is forecast to increase again. There's a hint of some wave activity downwind of Mt St Helena, but confidence isn't high enough that any wave will break and surface leading to stronger winds. Still thinking Mt St Helena could see gusts 60+mph. Given the offshore flow pretty dry conditions exist across the Bay Area too. Did a quick update to adjust winds and humidity across the forecast area for today. MM && .SHORT TERM... (Today and Friday) Issued at 1209 AM PST Thu Jan 9 2025 Gusty offshore winds have thankfully coming to and end across the Bay Area this morning. Some isolated gusts along the ridgetops of the interior North Bay mountains may linger through this afternoon, but are expected to be very isolated to these higher peaks. For example, as of writing, Mt. St. Helena is gusting to 60 mph, and Sonoma County Airport is at 0 mph. Overall today will be a very nice day across the Bay Area and Central Coast with mostly clear skies and temps in the 60s to lower 70s. Much of the same Friday with temps perhaps a bit lower due to an incoming cold front associated with a transient upper low set to push through the Great Basin this weekend. && .LONG TERM... (Saturday through Wednesday) Issued at 1209 AM PST Thu Jan 9 2025 By Saturday, surface high pressure begins to build over the PNW and Great Basin, once again promoting offshore winds. At this time, the forecast has trended downwards slightly in terms of magnitude, but winds will likely be more widespread across the North Bay and Bay Area. The current forecast keeps things under Wind Advisory criteria, but we are keeping a close eye on the Saturday night/Sunday morning timeframe. The offshore pressure gradient lingers through the first half of next week with a deepening upper low moving into the Desert SW. However, there is still a good deal of uncertainty with exactly how this slow moving and nearly stagnant upper low pattern will play out, and the uncertainty as of now mainly exists in varying degrees of offshore wind. The other impactful bit of weather over the next few days will be the cool overnight temperatures this weekend and early next week. Overnight lows are currently forecast in the mid- to- upper 30s in the North Bay valleys and interior Central Coast beginning Sunday morning into the middle of the week. && .AVIATION... (18Z TAFS) Issued at 945 AM PST Thu Jan 9 2025 VFR for all sites except STS through the TAF period. Ensemble guidance is indicating increased chances for LIFR conditions at STS after 12-13Z tomorrow morning with fog down to 1/4SM visibility possible. Confidence is low to moderate on this, however, with local WRF guidance keeping conditions at STS on the drier side overnight. Winds generally remain light to moderate and offshore through the period. Moderate drainage winds are expected to develop at SNS early tomorrow morning. Vicinity of SFO...VFR. Light, variable winds continue through the rest of the morning before winds shift more northerly this afternoon. Offshore winds return overnight with light, SE to at times variable winds expected. SFO Bridge Approach... Similar to SFO. Monterey Bay Terminals...VFR. Moderate SE drainage winds are expected this morning at both MRY and SNS and again tomorrow morning at SNS. Winds generally remain offshore, out of the E to SE, through the TAF period but will temporarily shift more northerly during the afternoon hours. && .MARINE... (Today through Tuesday) Issued at 945 AM PST Thu Jan 9 2025 High pressure over the Great Basin will result in generally light offshore winds across the bays and coastal waters through late tonight. Friday, high pressure is expected to weaken as a low pressure system moves eastward into the Pacific Northwest. Upper level ridging will then rebuild over the weekend and see a return to hazardous conditions for small crafts across the outer waters. Gusty, near gale force, northerly to northeasterly winds and elevated wave heights are expected to develop over the outer waters beginning late Friday and continue into early next week. The strongest winds will be located over the far northern outer waters where gale force gusts look most likely Saturday into Sunday. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...Small Craft Advisory from 3 PM to 9 PM PST Friday for Pt Arena to Pt Reyes 10-60 NM. && $$ SHORT TERM...Behringer LONG TERM....Behringer 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