Marine Weather and Tide Forecast for Tomales, CA

UPDATE
Issued at 916 PM PDT Mon May 19 2025

No major updates needed this evening. Wind gusts are on their way down this evening as the atmosphere stabilizes. Beautiful weak ahead with clear skies and warm temps.

SHORT TERM
Issued at 212 PM PDT Mon May 19 2025 (This evening through Tuesday)

Key Messages -Shallow marine layer returns -Breezy to gusty northerly flow -Elevated fire weather concerns

No major changes in the long wave pattern over the region the past 24 hours. However, details underneath have. High pressure aloft and at the surface continues to be the driver for sensible weather.
Sunny skies prevail again this afternoon, but as the N-S gradient begins to ramp up this afternoon one can see a shallow marine layer reforming. In fact, if one looks closely at the visible satellite imagery you'll notice standing wave clouds forming along the coastal terrain features sticking out in the NW flow (like Pt Reyes). So what does all this mean for the forecast? Coastal waters and coastal areas will see an influx of low clouds this afternoon and tonight. Winds will also increase with strongest winds over the waters, coastal areas, and terrain features inland oriented NW to SE (Santa Clara/Salinas Valleys). Lastly, since we're still around peak heating time there is still a concern for elevated fire weather conditions. There have been a handful of smaller veg fires the last few days and today is no different.

Generally speaking Tuesday will be more of the same: just a tad warmer and drier, especially inland. Tuesday morning will feature a few more marine layer clouds than Monday morning.

LONG TERM
Issued at 240 PM PDT Mon May 19 2025 (Tuesday night through next Sunday)

Key Messages -Warming and drying through Wednesday -Cooler, but dry weather returns Thursday and beyond

The peak of the warm up is still focused on Wednesday as high pressure is at its strongest. Have nudged temperatures slightly warmer across the interior as they'll have the least amount of influence from the onshore flow and cooler SST. Warmest locations will easily be in the 90s with interior Monterey making a run for 100 degrees. Given the warmer temperatures HeatRisk values will creep up to the Moderate category, but most of the forecast area remains in the Minor category.

Finally, a shift in the long wave pattern late Wednesday into Thursday. The high pressure ridge flattens and sinks southward as an upper level trough sweeps through NorCal/OR. The initial passing of this feature will kick off a cooling trend. To enhance the cool trend, a deeper and more broad upper trough moves through CA as we head into the weekend. Seasonably cool temperatures will develop and persist into next weekend. Despite these passing features the forecast remains dry the next seven days (outside of coastal marine drizzle).

AVIATION
(06Z TAFS)
Issued at 835 PM PDT Mon May 19 2025

It's VFR over land except patches of stratus and fog /LIFR-IFR/ are developing along the immediate coastline. Late afternoon and early evening satellite imagery showed standing waves within the stratus and fog.

The ACV-SFO pressure gradient is 7.2 mb, the UKI-STS pressure gradient is strong at 2.6 mb, the onshore gradient SFO-SAC is 2.7 mb. Pressure gradients initiate atmospheric motion; the overall pressure pattern in recent days has favored gusty northwest winds over the coastal waters and gusty west winds across the San Francisco Bay, this is common during spring and even early summer seasons. The marine layer varies in depth from several hundred feet to locally up over 1500 feet e.g. Fort Ord profiler.

A general convergence of higher dewpoint air (water vapor) in contact with chilly sea surface temps 50F-55F trapped beneath the lower level temperature inversion ahead of overnight cooling both due to temperature advection and radiative cooling to space favor additional stratus and fog /LIFR-IFR/.

Vicinity of SFO...Strong west wind continuing through the evening, with gusts 35-40 knots up through midnight. Increasing convergence of stratus and fog on the ocean side of the peninsula will likely advect on westerly wind reaching SFO late tonight and early Tuesday morning, a dry surface based cold front will move southward along the coast temporarily moving the stratus inland to the terminal before drier post frontal air moves in for early return to VFR Tuesday. West wind increasing to 20 to 30 knots with possibly higher gusts Tuesday afternoon and evening. Current HRRR output shows VFR for Tuesday night.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...It's currently VFR, however expect an increasing probability of stratus with patchy fog /LIFR-IFR/ with onshore winds 10 to 20 knots during the evening. Expect LIFR-IFR in stratus, fog including possibly a few patches of late night and/or morning drizzle tonight and Tuesday morning. Conditions improving to VFR by late Tuesday morning and early afternoon.
Onshore winds 10 to 20 knots Tuesday afternoon and early evening.

MARINE
(Tonight through next Sunday)
Issued at 810 PM PDT Mon May 19 2025

Surface high pressure will result in widespread strong northerly gale force gusts over the inner and outer waters through Tuesday.
Hazardous seas will persist Wednesday through Friday with strong northwesterly winds occasionally near gale force gusts.

MTR WATCHES/WARNINGS/ADVISORIES
CA...None.
PZ...Small Craft Advisory until 3 AM PDT Tuesday for SF Bay N of Bay Bridge.

Small Craft Advisory until 9 PM PDT Tuesday for Mry Bay.

Gale Warning until 9 PM PDT Tuesday for Pigeon Pt to Pt Pinos 0- 10 nm-Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0- 10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.

Gale Warning until 3 AM PDT Wednesday for Pt Arena to Pt Reyes 10-60 NM.