518
FXUS66 KMTR 250538
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
938 PM PST Mon Nov 24 2025

...New AVIATION, BEACHES...

.KEY MESSAGES...
Updated at 144 PM PST Mon Nov 24 2025

 - Dry and mild this week

 - Cooler temperatures this weekend as the next system approaches

 - Confidence increasing for gusty offshore winds by the end of the
   upcoming weekend

&&

.UPDATE...
Issued at 907 PM PST Mon Nov 24 2025

Fog is creeping into the coastal North Bay, interior Contra Costa
County, and just barely clipping inter Alameda County. The Byron
Airport in Contra Costa County is reporting less than 1/4 statute
mile visibility, fog, and overcast skies at 200 ft. The North Bay
isn`t doing much better with Petaluma reporting 1/4 SM visibilities
and fog and the Novato/Gnoss Airport reporting 1 1/2 SM visibilities
and mist. If you are driving in the North Bay or East Bay tonight
you may encounter locally dense fog. Remember to slow down, leave
extra time to reach your destination, and prepare for unexpected
changes in visibility while driving. Fog may spread further into the
Bay Area overnight but for now confidence is highest that fog will
impact the North Bay and East Bay. Otherwise forecast remains on
track.

&&

.SHORT TERM...
Issued at 144 PM PST Mon Nov 24 2025
(This evening through Tuesday)

A mid/upper level ridge is building into the region from the
southwest and will result in a gradual warming trend through
Wednesday or Thursday. As such, temperatures this afternoon will
warm into the 60s across inland areas while upper 50s are expected
near the coast. Overnight, we are expecting less cloud cover and fog
than the previous days as weak offshore flow persist in the higher
elevations across the region and will work to compress the marine
layer. However, cannot rule out patchy dense fog in the North Bay
valleys in responds to drainage flow in the Russian River valley
and East Bay valleys as tule fog spills in from the Central Valley.
Temperatures overnight are likely to range from the 40s across the
interior and lower 50s near the coast.

The warming trend will continue on Tuesday with the warmest interior
spots in the southern Santa Clara Valley, Hollister Valley, and
interior Central Coast reaching up to around 70 degrees F.

&&

.LONG TERM...
Issued at 144 PM PST Mon Nov 24 2025
(Tuesday night through next Sunday)

Wednesday and/or Thursday will be the warmest days of the week as
the aforementioned ridge continues to build aloft. This is when we
are expecting lower 70s in the Santa Clara Valley, Hollister Valley,
and interior Central Coast under mostly sunny skies. These
temperatures will be up to 10 degrees above seasonal averages.

From the previous forecaster: "Towards Friday into the upcoming
weekend, a pattern change will occur as the ridge over the western
United States breaks down, and one amplifies upstream across the
Gulf of Alaska. As a result, cold Arctic air descends into the
Mountain West and Central Plains states. Ensemble model guidance
continues to point to this system following more of an inside slider
like development in our region. In other words, the impacts of this
trough fall into the windy and dry side rather than the rainy side.
Still too early to tell how strong the impacts will be and where the
greatest threats will occur, but the current forecast has a period
of gusty offshore winds developing across the Bay Area and Central
Coast late Saturday through, and somewhat beyond, the end of the 7-
day forecast period. Confidence in the exact nature of the impacts
will improve through the rest of the week, so keep in touch with the
forecast updates for the most up to date information."

&&

.AVIATION...
(06Z TAFS)
Issued at 938 PM PST Mon Nov 24 2025

Conditions vary from VFR to LIFR including a few areas of hazy
skies this evening. A shallow cool frontal boundary is moving
southward over the coastal waters while low ceilings, fog and tule
fog are slowly advancing back into our easternmost forecast area.
A stable air mass including a lower precipitable water (0.52") on
the 00z (4 pm) Oakland upper air sounding compared to 0.72" 12z
(4 am) this morning favors improving radiative cooling tonight and
Tuesday morning. Light offshore winds per SAC-SFO 0.8 mb and WMC-
SFO 2.1 mb support a reversal of maritime influence we had over
the weekend (which helped limit dense fog coverage), with an
increasing continental influence reaching into our forecast area,
including a tule fog intrusion from the east tonight and Tuesday
morning. So far not seeing any numerical weather prediction
mesoscale models showing any significant boundaries forecast to
disrupt the light offshore wind pattern Tuesday morning which may
allow the fog intrusion to the Bay Area to linger during the day,
minus incoming solar heating Tuesday. This may favor a positive
feedback loop of more dense fog Tuesday night/Wednesday morning.

Vicinity of SFO...VFR likely continues through the evening. There`s
an increasing probability 20%-30% of IFR per recent HREF between
09z-16z Tuesday, 00z/06z SFO TAF has tempo IFR ceiling 13z-17z
Tuesday, but caveat is persistent light NE-E wind may transport
even lower conditions to VLIFR-LIFR during this time. It`s a low
confidence forecast since it`s still many hours from now, however
weather conditions and the time of year (plus recent generous early
season rain) are all favorable for aforementioned conditions and
it needs to be closely monitored. As such, it is a low confidence
forecast as to the return and duration of VFR Tuesday, if the
model forecasts are under-forecasting the extent of fog it may
take longer to mix out to VFR than currently 17z advertised in the
TAF.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Low to moderate confidence VFR continues
through late evening and overnight here. Current satellite imagery
supports VFR forecast to late evening at least. Nocturnal radiative
cooling will set up cool air drainage winds for tonight and Tuesday
morning providing a mixing wind to help prevent the development of
stratus and/or fog. Cool front and air mass passes by to our west,
HREF/HRRR model ouput show dry, cool air drainage mixing winds and
VFR prevailing tonight and Tuesday morning. VFR continues Tuesday
afternoon with winds gently shifting back to light onshore in the
mid to late afternoon. Low confidence VFR forecast Tuesday evening.

&&

.MARINE...
(Tonight through next Sunday)
Issued at 907 PM PST Mon Nov 24 2025

High pressure will persist over the coastal waters through mid to
late week. Seas will gradually ease through the middle of the
week with gentle to moderate northerly breezes. Winds will begin
to increase again late week, building moderate to rough seas.

&&

.BEACHES...
Issued at 923 PM PST Mon Nov 24 2025

The Beach Hazards Statement has been extended through 10 AM PST
Tuesday. 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 Tuesday morning for CAZ006-505-
     509-529-530.

PZ...None.
&&

$$

SHORT TERM...RGass
LONG TERM....RGass
AVIATION...Canepa
MARINE...Canepa

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