424
FXUS66 KMTR 240600
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1000 PM PST Sun Nov 23 2025

...New AVIATION...

.KEY MESSAGES...
Updated at 210 PM PST Sun Nov 23 2025

 - Quiet week ahead. Great for yard work and holiday activities.

 - Cooler temps this weekend as next system approaches.

 - Potential increasing for gusty offshore winds by the end of the
   weekend.

&&

.UPDATE...
Issued at 859 PM PST Sun Nov 23 2025

The satellite imagery this evening has been quite fun to watch, as
it has been a battle of the airmasses. Stagnant and moist air over
the Valley and the marine layer from our service area. There has
been a decent amount of growth with both, with the stratus now
cover much of the Bay Area valleys. Stratus has blossomed for
portions of the Central Coast too, particularly the southern
Monterey Bay and the Salinas Valley. Expect the stratus to
continue to sock in tonight, with the main forecast question being
fog. Currently dense fog remains confined to the Byron area,
while patches of fog are being observed around Concord, San Jose,
and Novato. At this time it is too early to hoist an Dense Fog
Advisory; however, we may need one hoisted later tonight or by
early tomorrow morning. If you`re joining the morning commute on
Monday, consider allowing extra time for it. Patchy dense fog is
possible, which will lead to sudden drops in visibility. You can
practice fog safety by checking the forecast and weather
conditions before you go, allowing extra time for your commute,
slowing down when visibility is reduced, and using your low beam
lights.

&&

.SHORT TERM...
Issued at 210 PM PST Sun Nov 23 2025
(This evening through Monday)

Marine layer more solidly in place today as the weak offshore
gradient reverses to weak onshore. Still some airmass compression
going on with weak ridging in place in the wake of last week`s
system. Decided not to make any adjustments to high temps today in
the North Bay despite persistent cloud cover keeping things
cooler. There is some signal that they will mix out rapidly this
afternoon and temps rebound a bit. Probably still remaining a bit
cooler than forecast though. Tonight and tomorrow are basically
persistence forecasts (copy/paste) with the weak ridge prevailing
and 500 mb heights basically staying stagnant.

&&

.LONG TERM...
Issued at 210 PM PST Sun Nov 23 2025
(Monday night through next Saturday)

If you`ve read the discussion for the past few days, you already
know what`s going on. It`s a frustrating pattern, but one very
important to keep an eye on. No noteworthy changes to the forecast
today, so I`ll give a general recap of what we`re looking at. Very
quiet through this week with a gradual warming trend as we go.
Seriously, it`s going to be a great week, weather-wise. However,
by the end of the week things change pretty aggressively in the
general upper level flow pattern. Still looking at a very deep
upper low diving south into the Western US as a result of a very
high amplitude ridge building up into NW Canada and Alaska.
Ensemble guidance has come to a better agreement that we`ll likely
see the windy and dry side of this system. What are the impacts
and when do they start? A bit too early to tell exactly the
magnitude and location of the impacts, but right now it looks like
we`ll potentially start to see offshore winds increasing in the
North Bay by the end of this forecast period, late Saturday.

Confidence in impacts will undoubtedly increase through the coming
days, so be sure to keep up with the forecast for the most up to
date information.

&&

.AVIATION...
(06Z TAFS)
Issued at 1000 PM PST Sun Nov 23 2025

The inland stratus intrusion has momentum to it this evening,
from a surface pressure perspective SFO-WMC and SFO-SAC gradients
are both weakly onshore (vs 24 hours ago WMC-SFO was 5.5 mb).
Satellite, surface observations including a recent spotter report
from Pleasant Hill indicate stratus ceilings and onshore winds are
to some extent along the leading edge blending in with the western
edge of tule fog /VLIFR/ that is in parts of the East Bay. A lower
level cyclonic circulation with drier air is also intruding in along
the back side of the stratus along the coastline at least temporarily
mixing out the stratus.

Observations are still VFR-MVFR over the forecast area except IFR-
LIFR due to residual evening stratus and fog in the East Bay and the
North Bay. As mentioned, cooler air from the surface to lower levels
continues to filter in from the west and northwest, ceilings tonight
and Monday morning will be a mix of MVFR and IFR-LIFR including
possibly VLIFR in dense fog. The 00z (4 pm PST) Oakland sounding,
much like this morning`s 12z sounding, showed a lower level subsidence
temperature inversion based near 1500 feet; cooler air remains well
entrenched under the temperature inversion with additional cooler air
arriving tonight and Monday morning per NAM output (with additional
loss of heat to space via radiative cooling where it`s initially
dry/clear sky). For tomorrow HREF shows clearing by 21z (1 pm PST)
across the Bay Area, suggesting improving mixing may result in earlier
mix out times compared to today.

Vicinity of SFO...Currently it`s back to VFR with a dry air
intrusion from the north. Best guess is that night-time cooling
and cool air advection will help redevelop a stratus ceiling with
tempo MVFR 06z-10z then MVFR prevailing until 20z Monday. West
wind 10 knots decreasing to light westerly wind then near 10 knots
Monday afternoon and evening.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...MVFR-IFR tonight and Monday morning. VFR
by late morning and early afternoon Monday. Light and variable winds
to light southeasterly winds tonight and Monday morning, then shifting
to onshore 5 to 10 knots Monday afternoon and early evening.

&&

.MARINE...
(Tonight through next Saturday)
Issued at 859 PM PST Sun Nov 23 2025

High pressure will persist over the coastal waters through mid and
late week. Seas will gradually ease Monday through the middle of
the week with gentle to moderate northerly breezes. Winds begin to
increase along with building seas by the end of the week and into
next weekend.

&&

.BEACHES...
Issued at 614 PM PST Sun Nov 23 2025

A Beach Hazards Statement is in effect through Monday evening. A
long period northwesterly swell will result in an increased risk
for sneaker waves and rip currents. Breaking waves of 13 to 18
feet are expected. Sneaker waves can unexpectedly run
significantly farther up the beach than normal, including over
rocks and jetties. Rip currents are typically more frequent and
stronger in the vicinity of jetties, inlets, and piers.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement through Monday evening for CAZ006-505-
     509-529-530.

PZ...Small Craft Advisory until 3 AM PST Monday for Pigeon Pt to Pt
     Pinos 10-60 NM.

&&

$$

SHORT TERM...Behringer
LONG TERM....Behringer
AVIATION...Canepa
MARINE...Canepa

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