Marine Weather and Tide Forecast for Diablo Grande, CA

SHORT TERM
(Tonight through Thursday)
Issued at 1054 PM PST Tue Jan 14 2025

While low elevation temperatures are running a degree or two colder than 24 hours ago, surface dew points are around 5 degrees higher than last night. This will put a limit on the cooling tonight, as moist air cools much less efficiently than dry air.
As a result, the minimum temps will be a few degrees higher than yesterday and there may be some mist in the air near river valleys. Despite this, it will still be a chilly start across the Bay Area and Central Coast with temperatures dropping into the upper 30s and low 40s across the Bay Area, and down to the low 30s across inland portions of the Central Coast. After the chilly start, it will be another beautiful day with plenty of sunshine, high temps in the 60s and light winds.

LONG TERM
(Thursday night through next Tuesday)
Issued at 1054 PM PST Tue Jan 14 2025

There are some interesting developments in the long term forecast.
The overall pattern continues to be dominated by high pressure offshore, and Wednesday and Thursday will be very similar to the previous few days. By Friday, a weak cold front will move through from the north, bringing cooler temperatures and some clouds (no rain) back to the Bay Area skies. The 1000-500 mb thickness and 850 mb temperature will only drop slightly, but the disturbance will bring the return of onshore flow, and even a marine layer. Remember the marine layer? The cold front will also cause the max and min temps to drop, and more widespread frost advisories are expected this weekend into early next week. The onshore wind won't last long. While the uncertainty balloons by Saturday, it looks like there will be a return to offshore winds.
There is now a bi-modal solution in the ensemble guidance regarding how strong these winds will be. The deterministic SJSU 2km WRF with GFS boundary conditions shows the SFO-WMC gradient dropping below -18 mb by Monday. This would bring critical offshore winds with hydraulic jumps and gusts in the 60-80 mph range. However, a peak at the ensemble solutions show roughly 50% support for this high end event, with the other members much less aggressive, huddled around -4 mb. There are no solutions in the vast gap between these two. This makes the forecast extremely tricky. On one hand, it might make sense to split the difference and go with the ensemble mean. The problem is that the mean has no support in the individual solutions. The other option is to pick one of the 2 extremes and message the uncertainty. That's what we will do for now. I am going with the weak scenario since it has been more consistent in previous model runs. However, this new emerging solution is too strong to ignore, so we will begin messaging the possibility of very strong offshore winds. Just know it can still go either way. While there is plenty of time for the guidance to change, right now it looks like the winds will either be gentle or just about as strong as they get on Monday. Stay tuned.

If you're here to see if it's going to rain anytime soon, it's not. We're looking dry through the end of next week, at least.

AVIATION
(12Z TAFS)
Issued at 320 AM PST Wed Jan 15 2025

Generally VFR with some patchy fog (IFR to MVFR) in the N Bay.
Winds generally light and variable/to drainage flow. Patchy fog again Thursday morning.

Vicinity of SFO...VFR.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR.

MARINE
(Today through Monday)
Issued at 320 AM PST Wed Jan 15 2025

High pressure to the north will keep light and variable winds over the coastal waters. Winds will ultimately become more northerly by Thursday. Northerly winds will gradually increase on Friday and persist into the weekend. Seas will build over the weekend with increasing winds.

BEACHES
Issued at 322 AM PST Wed Jan 15 2025

Still some energetic surf zone early on Wednesday with a moderate period northwest swell. The northwest swell will gradually subside later Wednesday. There is a slight risk of sneaker waves.
Remember to never turn your back on the ocean.

MTR WATCHES/WARNINGS/ADVISORIES
CA...Frost Advisory until 9 AM PST this morning for CAZ516>518.

PZ...None.