FXUS66 KMTR 241751
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
951 AM PST Mon Nov 24 2025
...New AVIATION...
.KEY MESSAGES...
Updated at 1226 AM PST Mon Nov 24 2025
- Dry and mild this week with stratus overnight and through the
morning
- 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 855 AM PST Mon Nov 24 2025
Low clouds blanket much of the inland valleys this morning, but are
forecast to mix out by late morning or early afternoon. Fog was not
as prevalent this morning with only isolated pockets of dense fog
around Santa Rosa and Byron, but already seeing improvements in
visibilities at Byron and Santa Rosa will be soon to follow. That
said, the forecast remains on track this morning with no updates
anticipated at this time.
RGass
&&
.SHORT TERM...
Issued at 1226 AM PST Mon Nov 24 2025
(Today and tonight)
The stratus layer envelops most of the Bay Area valleys and extends
in to the Monterey Bay and Salinas Valley regions, with the
expectation that the layer continues to build through the night
somewhat undercut by the clearing of the Santa Rosa Plain. Will
monitor how the stratus evolves through the night, but will hold
firm on seeing a general expansion of the stratus layer through the
rest of the morning. A more pressing question will be how dense fog
evolves through the next several hours. At this point the only
station that has consistently reported dense fog (1/4 mi visibility
or less) is Byron in the southeastern corner of Contra Costa County,
with trends across the Central Valley suggesting that dense fog is
also present across the eastern tier of Contra Costa County (east of
the Diablo Hills, including the Antioch area). Fog has also been
reported across other regions of the Bay Area, including Concord and
Novato, but we have not seen the widespread dense fog anywhere that
would trigger a Dense Fog Advisory. If observations show more
widespread fog development, one may need to be issued later this
morning. For those morning commuters who do encounter dense fog,
slow down, use low-beam headlights, and allow extra distance between
you and the car in front of you. In any case, stratus should begin
to dissipate sometime after sunrise and be generally cleared out by
the afternoon.
The weather pattern remains largely similar to yesterday's with a
weak ridge aloft and a gentle onshore flow this afternoon. High
temperatures range from the middle to upper 60s in the inland
valleys to the upper 50s to middle 60s across the coastal and
Bayside regions.
&&
.LONG TERM...
Issued at 1226 AM PST Mon Nov 24 2025
(Tuesday through Sunday)
A building ridge aloft brings a gradual warming trend for Tuesday
into Thanksgiving (Thursday), compressing the marine layer and
raising temperatures by a few degrees, with the rise in temperatures
somewhat balanced out by some cold air advection stemming from an
interaction between a building high in the east Pacific and a
building low in the Desert Southwest. The warmest spots of the
inland valleys (think the Morgan Hill-Gilroy region and the southern
Salinas Valley) might touch the lower 70s on Wednesday and Thursday.
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...
(18Z TAFS)
Issued at 933 AM PST Mon Nov 24 2025
Low clouds are mixing out and clear skies will prevail through the
rest of the day. Synoptic winds will be light with a gentle
onshore sea breeze in the afternoon. While the short term is
straight forward, the forecast gets a little more challenging
overnight. The interaction between building high pressure in the
mid levels and a deepening coastal trough at the surface make the
uncertainty balloon early Tuesday morning. While the wind speed
will be light, the direction is hard to pin down. The boundary
layer wind direction plays a big role in the formation of stratus
and fog, so uncertainty in the direction means uncertainty in the
flight conditions. The TAFs lean optimistic, but there is a
notable chance for Thule fog to spill over through the Delta and
impact some Bay Area terminals early Tuesday morning.
Vicinity of SFO...The stratus scattered out at 1717Z, a couple
hours earlier than yesterday. These low clouds will continue to
clear in the short term. Winds will eventually flip to the typical
westerly direction this afternoon, but the exact timing is hard to
pin down. There is a roughly 20% chance for both MVRF ceilings
and/or visibility impacts Tuesday morning. This trend has been
gradually decreasing since the last TAF update.
SFO Bridge Approach...There is some haze over the Bay on the
cameras that hasn't been reported at the terminal. This may
impact the bridge approach visuals for the next few hours before
the residual moisture mixes out.
Monterey Bay Terminals...The ceilings have held on longer than
they were supposed to this morning. MRY is on the verge of
clearing, but the satellite trend shows a new pulse of stratus may
push the clearing time a couple more hours. SNS is fully socked in
and should have a similar clearing time. Afterwards the clear
skies should prevail through the day with gentle diurnally driven
winds. Towards the end of the TAF period, there is a 30-40% chance
for stratus to return, with an IFR cloud base expected if it
does.
&&
.MARINE...
(Today through Saturday)
Issued at 855 AM PST Mon Nov 24 2025
The swell will continue to subside over the next couple days as
high pressure brings favorable conditions across the area. Winds
will begin to increase again late week, building moderate to rough
seas.
&&
.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 this evening for CAZ006-505-509-
529-530.
PZ...None.
&&
$$
SHORT TERM...DialH
LONG TERM....DialH
AVIATION...Flynn
MARINE...Flynn
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Prepared by Boulder-Creek.com Weather at: Mon Nov 24 12:30:02 PST 2025
From the National Weather Service
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