FXUS66 KMTR 230051
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
451 PM PST Sat Nov 22 2025

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 202 PM PST Sat Nov 22 2025

 - Dry and mild through this week. Morning stratus returns.

 - Gradual warming trend through Thanksgiving. High temps near
   normal or a couple degrees above.

 - Confidence increasing in a drier outcome for the storm just
   outside 7 days.

&&

.SHORT TERM...
Issued at 202 PM PST Sat Nov 22 2025
(This evening through Sunday)

As stated, nearly copy/paste from yesterday with almost everyone
within 3-4 degrees from 24 hours ago. Spread of surface obs
showing a hint of a marine layer forming topping out around 1000
feet. Some additional hints of more moist NW flow as well as
marine stratus starts to form of the coast of Sonoma and Marin
counties. This stratus trend will likely continue southward as we
hang on to the marine layer going into tonight. Slight chance of
valley fog going into Sunday morning as well. Another great
weather day Sunday with temps a couple of degrees cooler than
today.

&&

.LONG TERM...
Issued at 202 PM PST Sat Nov 22 2025
(Sunday night through next Friday)

Quiet and dry conditions continue through most of next week as a 
slight warming trend ensues under the influence of a broad high 
pressure ridge aloft. As we approach the end of the week, the
ridge starts to break down amid very strong ridge amplification
upstream into the Gulf of Alaska. The result a couple a days later
will be a fairly notable southward dive of the jet stream and
displacement of very cold air from the arctic into the mountain
west and central plains. Guidance is starting to show more
agreement on a more eastward trajectory of the trough axis, which
would be the drier solution for us - potentially completely dry.
At this point we're leaning more towards the potential of gusty
offshore winds across the North Bay just beyond our 7 day period.
As always, stay tuned to the forecast for the latest. Slight 
shifts in a system like this can mean very different things for 
us. 

&&

.AVIATION...
(00Z TAFS)
Issued at 451 PM PST Sat Nov 22 2025

Late afternoon satellite imagery shows it's clear /VFR/ except 
for an area of low stratus and fog over the coastal waters 
including partial coverage of low stratus/fog from the coastal 
North Bay to the San Mateo county coastline. Low stratus and fog 
are associated with a surface to lower level (~ 1000 mb level) 
pool of cooler air on northwest winds; buoys show air temps are 
cooler than sea surface temps and dewpoint temps are slightly 
lower than sea surface temps, ideal for ongoing development. With 
the onset of night-time radiative cooling to space, this also 
favors ongoing low stratus and fog /LIFR-IFR/. 

The other side of things is the continental influence per currently
5.0 mb WMC-SFO offshore directed pressure gradient and the SFO-SAC
pressure gradient is essentially flat. HREF is showing tule fog 
redevelopment in the Central Valley & light offshore winds 
transporting tule fog /VLIFR-LIFR/ into parts of at least the East
Bay late tonight and Sunday morning. A lower November sun angle 
equals less diurnal heat input i.e. a thermodynamics consideration,
meaning less heat into a system like the atmosphere takes longer 
to increase the internal temp and as such may delay mixing out of 
fog Sunday. HREF does currently show patches of IFR lingering to 
early Sunday afternoon. Recent NAM output shows the aforementioned
near surface pool of cooler air continuing Sunday night to Monday
morning, further providing for low stratus/fog, except high clouds
may introduce another factor i.e. possibly slowing radiative cooling
a little Sunday night.

Vicinity of SFO...5 minute observations at 23z today showed the 
wind shifted to west-northwest direction 10 knots with low 
stratus/fog in the San Bruno Gap. Much of whether or not the low 
stratus/fog makes it to SFO depends on the momentum of the pool of
cooler air over the coastal waters, while the SFO-SAC pressure is
essentially flat at 0.1 mb. With sunset, surface temps inland 
will begin to cool and equal sea surface temps limits onshore 
gradient, seasonally this typically begins in November because of
the start of the cool season. Current guidance shows VFR continuing
through the evening, 00z TAF continues VFR through the evening, 
with an increasing probability of LIFR-IFR in low stratus/fog 
overnight and Sunday morning; 18z HREF today shows a 40% 
probability of IFR at 21z (1 pm PST) Sunday.

SFO Bridge Approach...Similar to SFO. VFR this evening, then 
there's increasing probability of LIFR-IFR tonight and Sunday 
morning, with 30%-50% probability of IFR lingering Sunday 
afternoon.

Monterey Bay Terminals...Moderate to high confidence VFR continues
through the evening, then increasing probability of low stratus 
/LIFR-IFR/ possibly including fog overnight and Sunday morning as 
well. Onshore winds 5 to 10 knots diminishing and becoming mainly 
light southeast winds tonight and Sunday morning. Winds shifting 
to onshore 5 to 10 knots mid to late Sunday afternoon.

&&

.MARINE...
(Tonight through next Thursday)
Issued at 343 PM PST Sat Nov 22 2025

Moderate seas will prevail through late Sunday, resulting in
hazardous marine conditions. Seas are forecast to subside through
the middle of the upcoming week. Gentle to moderate northerly
breezes will persist through at least midweek. Heading towards
late week, winds are forecast to increase and seas build.

&&

.BEACHES...
Issued at 935 AM PST Sat Nov 22 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 9 AM PST Sunday for Pt Arena to Pt 
     Reyes 0-10 nm.

     Small Craft Advisory until 9 PM PST Sunday for Pt Arena to Pt 
     Reyes 10-60 NM.

     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...RGass

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Prepared by Boulder-Creek.com Weather at: Sat Nov 22 20:30:02 PST 2025