Pigeon Point to Point Piedras Blancas between 60 and 150 NM Offshore Forecast
| Today...Nw Winds 10 To 20 Kt, Becoming N To Nw 5 To 15 Kt. Seas 10 To 12 Ft. |
| Tonight...Nw Winds 5 To 15 Kt, Diminishing To Less Than 10 Kt. Seas 9 To 11 Ft. |
| Sun...Variable Winds Less Than 10 Kt. Seas 9 To 10 Ft. |
| Sun Night...S Winds Less Than 10 Kt, Increasing To 10 To 20 Kt. Seas 7 To 9 Ft. |
| Mon...S Winds 10 To 20 Kt, Becoming Sw. Seas 7 To 10 Ft. |
| Mon Night...Nw Winds 5 To 15 Kt, Becoming 5 To 10 Kt. Seas 8 To 10 Ft. |
| Tue...W To Sw Winds 5 To 10 Kt. Seas 9 To 10 Ft. |
| Tue Night...S To Sw Winds 5 To 15 Kt. Seas 7 To 9 Ft. |
| Wed...S To Sw Winds 5 To 15 Kt. Seas 7 To 11 Ft. |
| Wed Night...W To Sw Winds Less Than 10 Kt. Seas 9 To 11 Ft. |
| Area Forecast Discussion National Weather Service San Francisco CA 1031am PDT Sat September 27 2025 .SHORT TERM... Issued at 227am PDT Sat September 27 2025 (Today and tonight) Overnight satellite fog product shows quite the difference N to S across the forecast area - either you have marine layer clouds or you don't and the break point is Santa Cruz. Santa Cruz coast, Monterey Bay, and Salinas Valley all have marine layer clouds. Elsewhere is clear. A battle of pressure gradients is a key player in this setup. The stronger N-S gradient from SFO- ACV initially helped to keep marine layer clouds out of the area. That gradient relaxed and we saw a S-N gradient from SFO-SMX increase bringing clouds northward along Big Sur and Santa Cruz. Their northward track is halted around Monterey Bay due to drier air northward and weak offshore flow. The bigger story for today and tonight, the 5 to 15 degree cool down across the region. The shortwave ridging that brought the hot weather Friday is quickly being replaced by an approaching trough dropping 500mb heights. The airmass aloft also has a 2-3 degree C drop. Despite some afternoon sunshine temperatures today will be 60s to 70s coast and 70s to mid 80s inland. The marine layer will have a better shot at reforming tonight with the falling heights and cooler airmass. Long Term Issued at 327am PDT Sat September 27 2025 (Sunday through Friday) To round out the weekend temperatures will drop another 5 to 10 degrees with further falling 500mb heigheights as the upstream trough begins to really assert itself over the West Coast. Sunday will be dry, but highs will be 60s and 70s most areas, which is 5 to 10 degrees below normal. Sunday night into Monday is the transition period back to wet weather. While the upstream trough knocks on our door the surface reflection shows warm sector intrusion from the low pressure parked off the PacNW coast. Taking a peek at isentropic surfaces 295-300k show decent isentropic lift / upglide over NorCal, including the North Bay. As a result, moisture will increase leading to increasing clouds and steady stratiform precip. Speaking of moisture, still a solid feed back the HI with PWATs (Precipitable Waters) of 1-1.5" or 150% PON. This scenario will persist into the Monday AM commute with precipitation most likely along the coast and north of San Jose. By Monday afternoon the cold front approaches from the north and makes its way S and E through early Tuesday. The frontal passage will have a lot more dynamics to work with as the jet streak rounds the base of the upper trough, cyclonic curvature, providing larger ascent. A few convective parameters are still being highlighted with the frontal passage - higher lapse rates, MUCAPE, and modified Total Totals. Longer range models are showing some hints of a NCFR on Monday too. Still far out to dial in those features just yet. Additionally, while convective parameters are still being shown they are trending less and farther north. One part of the forecast that hasn't really changed with the Monday frontal passage is that it will weaken by the time it reaches the Central Coast. Post frontal showers will develop Monday night and Tuesday. Post frontal showers will be the brief "break" before system two arrives later Tuesday into Wednesday. Just like system one this system will have some tropical moisture too, but just a different flavor. The source region of this moisture will be the remnants of TS Neoguri currently in the WPac. Showers will increase in coverage and intensity by Tuesday evening/night over the N Bay before spreading S and E Wednesday. It too will fade over the Central Coast. One interesting trend that may be developing with system two is a stalling moisture plume. Upper level steering flow becomes parallel to the surface boundary. Atmospheric River guidance shows a solid feed of higher IVT wavering over the N Bay and SF Bay area. That would be a much longer period of precip. Current forecast doesn't quite reflect this scenario just yet, but we'll need to watch it closely. As mentioned on previous discussions system two looks less convective too. Interesting to note that system two will arrive just in time for the upcoming water year, which begins Oct 1. Storm total Quantitative Precipitation Forecast with both system remains in the 1-1.5" North Bay, but definitely has trended drier Golden Gate southward. In fact, interior Central Coast will be struggling to get a 0.01". Drier weather return by Thursday. Marine (Today through Thursday) Issued at 1029am PDT Sat September 27 2025 Winds continue to diminish this morning, becoming moderate to fresh, and seas subside by late Saturday. Strong southwesterly breezes will persist over the San Pablo Bay, Suisun Bay, the West Delta and the San Francisco Bay north of the Bay Bridge this afternoon and evening. An approaching upper level trough and surface cold front will bring rain, isolated embedded thunderstorms, and building seas to the coastal waters Monday into early Tuesday. A second system will arrive Tuesday into Wednesday and continue rain chances across the coastal waters. NOAA San Francisco Bay Area Office: Watches - Warnings - Advisories CA...None. PZ...Small Craft Advisory until 9pm PDT this evening for SF Bay N of Bay Bridge. x.com/nwsbayarea |
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