FXUS66 KMTR 050450 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 850 PM PST Tue Nov 4 2025 ...New AVIATION... .KEY MESSAGES... Updated at 257 AM PST Tue Nov 4 2025 - Wind gusts of 45 to 65 mph are forecast for portions of the North Bay, East Bay, SF Bay, and Santa Cruz Mountains. - Low potential for nuisance flooding in the North Bay, but moderate rainfall will be largely beneficial. - Thunderstorm chances remain around 10 to 20 percent with the main hazards being pockets of heavier rainfall and enhanced outflow winds. && .UPDATE... Issued at 804 PM PST Tue Nov 4 2025 Forecast on track so far this evening. Faint hints at early rainfall showing up on radar offshore of the Mendocino coast. Surface analysis shows the warm front currently draped along the NorCal coast with the strong cold front lagging behind. The warm front is still expected to sag southward over the next few hours, promoting light rain in the North Bay before the cold front moves through tomorrow morning. Winds are gradually increasing across the Bay Area and we're seeing gusts in the 50-65 mph range currently occurring off the coast just south of Eureka. Winds of similar magnitude are still expected along the North Bay coast associated with the cold front. Behringer && .SHORT TERM... Issued at 146 PM PST Tue Nov 4 2025 (This evening through Wednesday) Rest of this afternoon - Lots of talk about the upcoming impactful weather, but today so far has turned to to be pretty nice. Mostly sunny skies for a majority of the forecast area with clouds beginning to fill in over the North Bay as we speak. Temperatures have been seasonably mild and in the 60s to 70s. This evening through Wednesday. All focus of the next seven days quickly shifts west and northwest. Impressive water vapor imagery across the NE Pacific as cyclogenesis continues with a deepening low pressure system. Latest OPC surface analysis shows a 979mb low deepening near 45N 145W tracking toward the PacNW. The cyclogenesis is being fueled by a solid 130+kt jet. We'll break this section into the main three impacts. Wind: Surface pressure falls continue to stack up near and just ahead of the surface low with higher surface pressure lingering over CA. As result, surface pressure gradients are tightening with gusty winds developing. Already seeing some solid gusts over 50 mph along the Redwood Coast with one gust of 68 mph near Cape Mendocino. Only minor adjustments were made to the previous forecast. The stronger winds currently to the north will shift southward to the North Bay coast this evening and overnight as the surface low moves more south and east. By late tonight and early Wednesday the highest wind swath will be aimed right at the Golden Gate and Bay Area. Hi-res guidance captures this well, including our in-house WRF model. To add some extra juice to the wind, a cranking 925mb jet develops off the far NorCal coast and slowly shifts southward. Once the strongest wind swatch gets south of the Golden Gate it begins to lose upper level support. That doesn't mean strong winds won't impact San Mateo to Central Coast, just that the strongest winds will be focus over the North Bay coast and Golden Gate region. Gusts of 60-70 mph are still in play with High Wind Warning remaining for North Bay coast and Marin Headlands. Outside of High Wind Warning, Wind Advisory continues for N and E Bay, San Mateo Coast, and Santa Cruz Mts. Two other wind things to note: East Bay passes will be borderline for High Wind Warning criteria, but it's more isolated and not widespread for the entire E Bay. Santa Cruz and Monterey coast will be windy as well, but much smaller timescale so didn't include them in any wind products. Winds finally ease Wednesday evening. This will be the first real wind test of the season. Rain: The North Bay was teased with a few showers early this morning, but they have now shifted well to the north. The northward shift was well advertised as these scout showers were tide closer to the warm front/sector. This warm sector region will shift north as the cyclone deepens. The Bay Area has to sit tight and wait for better forcing/moisture tied to the cold front. Latest timing will be after midnight. Heavier rain will initially move into the N Bay (late tonight) before sliding south to the Bay Area (3-5 AM) and finally the Central Coast mid-morning Wednesday. This fropa looks to be rather dynamic with a 3-6 hour window of higher rain rate. Unfortunately, the timing looks to impact the Wednesday AM commute for the Bay Area. Latest guidance from the CNRFC and National Water Center show a rise in creeks/streams but no major flooding is expected. That being said, higher rain rates on urban areas and flashier creeks/stream will likely lead to minor to moderate flooding early Wednesday. We'll need to watch the Pickett Burn Area closely as there is a 40-50% chc of rain rate thresholds for Flash Flooding to be met. Rainfall totals tonight through Wednesday night have trended down a tenth or two - likely due to the more northward push this evening/early tonight. Rainfall will still be highest N Bay and terrain favored locations (Big Sur Mts/Santa Cruz Mts) with 1-2.5" locally 3+", Bay Area/S Bay 0.25-0.5", Interior Central Coast a few hundredths to a tenth or two. Give the S to SW flow rain shadowing will be a thing over the Santa Clara and Salinas Valleys. Thunderstorms: Still seeing some convective ingredients with the fropa. Previous forecast had a mention of thunderstorms and see no reason to take them out. Thunderstorms will be most likely from Redwood northward late tonight through Wednesday afternoon. About 15-25% chance with main impacts being heavy rain and gusty winds. && .LONG TERM... Issued at 245 PM PST Tue Nov 4 2025 (Wednesday night through next Monday) By Wednesday night the cold front will be through the region with post-frontal showers lingering. Moist boundary layer, clear skies, and weakening winds will set the stage for fog. Progressive zonal flow will develop through the extended leading to additional brushes with precip, but no big storm. Light rain will be possible Friday, but mainly north of San Jose. A brief break and then another shot of rain late Sunday into Monday. && .AVIATION... (06Z TAFS) Issued at 824 PM PST Tue Nov 4 2025 Slight delay in the onset of winds this evening, but current surface analysis shows the frontal system moving into the NorCal coast on its way south. Low confidence in the onset time of winds, but high confidence in fcst wind speeds between 12-16Z. Gusty S/SW winds will likely persist into the afternoon, but decreasing in speed. For terminals generally north of KSQL, high confidence in brief +RA between 13-15Z with possible development of a narrow cold frontal rain band. +RA comes to an end by 17-18Z where VCSH and MVFR/IFR cigs prevail through the rest of the evening Vicinity of SFO...Southerly winds are anticipated to persist thru the period, gradually increasing through tonight. Very gusty 35-45 kts by 12-15Z as the cold front moves thru. +RA will accompany the strongest winds before winding down by the 17Z hour. Through the rest of the period, mostly dry with VCSH and lingering MVFR/IFR cigs. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...Increasing cloudiness overnight as the cold front approaches. Perhaps the biggest impact to Monterey Bay terminals will be gusty southerly winds to 25-30 kts. Rain is still anticipated, but low chance of being heavy. SHRA is the more likely mode of precip. Rain to begin impacting terminal by the 18Z hour lasting through about 23Z. && .MARINE... (Today through Sunday) Issued at 1021 AM PST Tue Nov 4 2025 Widespread hazardous conditions to develop this afternoon before conditions rapidly deteriorate overnight as a low pressure system arrives. Southerly, near gale to gale force winds with widespread gale to severe gale force gusts tonight through tomorrow morning. Storm force gusts are expected across the northern waters from Point Arena to Pigeon Point. Moderate seas build, becoming rough to very rough, tonight through late week with significant wave heights between 10 to 16 feet expected. Rain chances increase throughout the day with moderate to heavy rain expected overnight tonight into tomorrow. Isolated embedded thunderstorms are possible Wednesday with the highest chances Wednesday morning into the afternoon. Wave heights abate and conditions improve by this weekend. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...Coastal Flood Advisory until 2 PM PST Saturday for CAZ006-506- 508-529-530. Wind Advisory until 4 PM PST Wednesday for CAZ006-503-504-506- 508>510-512-515. Beach Hazards Statement from late Wednesday night through Thursday evening for CAZ006-505-509-529-530. High Wind Warning until 4 PM PST Wednesday for CAZ502-505. PZ...Small Craft Advisory until 9 PM PST this evening for Mry Bay- Pigeon Pt to Pt Pinos 0-10 nm-Pigeon Pt to Pt Pinos 10-60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm-SF Bay N of Bay Bridge. Gale Warning until 3 PM PST Wednesday for Mry Bay-Pigeon Pt to Pt Pinos 0-10 nm-Pigeon Pt to Pt Pinos 10-60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm-SF Bay N of Bay Bridge. Gale Warning until 9 PM PST this evening for Pt Arena to Pt Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM-Pt Reyes to Pigeon Pt 0-10 nm. Storm Warning until 3 AM PST Wednesday for Pt Arena to Pt Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM-Pt Reyes to Pigeon Pt 0-10 nm. && $$ SHORT TERM...MM LONG TERM....MM AVIATION...Behringer MARINE...Kennedy 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