331
FXUS66 KMTR 041755
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1055 AM PDT Sat Oct 4 2025

...New AVIATION...

.KEY MESSAGES...
Updated at 1245 AM PDT Sat Oct 4 2025

 - Warmer and drier conditions through mid week.

 - Next chance for rain late next week.

&&

.UPDATE...
Issued at 802 AM PDT Sat Oct 4 2025

Weak offshore winds have developed over the higher terrain this
morning, however onshore winds are forecast to prevail this
afternoon in the lower elevations. Stratus remains over the San
Mateo County coastline, southward around the Monterey Bay Region,
into the Hollister Valley, and the southern Salinas Valley. These
clouds will dissipate through the remainder of the morning as
offshore flow persist aloft. Thus, temperatures will warm up into
the mid to upper 60s near the coast and mid to upper 70s inland.
These values remain near to slightly below seasonal averages. The
ongoing forecast remains on track this morning with no updates
anticipated.

RGass

&&

.SHORT TERM...
Issued at 1245 AM PDT Sat Oct 4 2025
(Today and tonight)

The 500 mb low has moved into Nevada and will continue NE while
being absorbed back into the long wave pattern over the next 24
hours. Meanwhile a surface low pressure trough will develop over
California. The gradient between this low pressure and building
high pressure over the subtropical Eastern Pacific will support
moderate N-NW winds along the coast and NW-SE oriented valleys.
The marine layer will gradually recover today as warmer, drier
air moves over the stable pool of cool air near the surface.
Temperatures will be near seasonal normal with mid to upper 70s
inland and mid to upper 60s along the coast. Overall a pretty nice
Saturday.

&&

.LONG TERM...
Issued at 1245 AM PDT Sat Oct 4 2025
(Sunday through Friday)

The trough over California will gradually shift towards the coast
starting Sunday, nudged by weak upper level troughing. The upper
level trough will evolve into a cut-off low off the Central Coast
by Sunday, further pushing the surface trough to the coast or even
offshore. As the surface trough shifts further west, high pressure
will build over the northern Rockies. This set up will support
down-gradient, offshore N or NE winds. These winds will bring a
warmer, drier air mass to the Bay Area from Sunday through mid
week. The 500 mb height will remain below the median for this
time of year (5800 m) which will moderate the temperatures and
should allow a 1,000-1,500 ft marine layer to survive under the
offshore winds. The skies will be clear in the afternoon, but
morning clouds are still expected in the typical marine layer
locations this week. While the minimum humidity will drop below
30% across the North Bay interior mountains, the mild
temperatures, moderate wind speed, and higher than normal fuel
moisture will limit fire weather concerns.

The offshore winds will die down by Friday as a new, deep low
pressure system approaches the west coast and becomes the dominant
feature. This system will bring a cold front through the Bay Area
next weekend, with some rain likely. The ensembles have backed
off on the amount, however. There is now a 10-30% chance of
receiving more than 1" of rain across the North Bay, with less
than 10% of reaching that threshold across the rest of the cwa.
The disturbed weather looks to last for several days, with
stratiform rain ahead of the front, and showers after it moves
through.

&&

.AVIATION...
(18Z TAFS)
Issued at 1055 AM PDT Sat Oct 4 2025
Most of the stratus has mixed out this morning, leaving
much of the area with VFR conditions. Expect any lingering clouds to
continue to dissipate through the afternoon. Stratus should return
this evening, and likely stay confined to the coast.


Vicinity of SFO...A few clouds may linger around SFO this afternoon,
with VFR conditions prevailing through at least the evening hours. A
few models hint at stratus trying to return again tonight and into
early Sunday morning, likely favoring around or just before sunrise.
Confidence is low on this given onshore flow is expected to develop.
If we do see stratus, a brief period of MVFR conditions may prevail
from 10Z-14Z. If that doesn`t pan out VFR conditions are expected
the through the TAF cycle. With winds shifting from onshore this
afternoon, to weak offshore flow late tonight or by early tomorrow
morning. Onshore flow returns mid Sunday,following a more diurnal
pattern.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...The southern half of Monterey Bay has
cleared out leaving much of the region with VFR conditions. Stratus
continues to hug around Santa Cruz County and the northern part of
the Bay, but should hopefully clear out for the afternoon. Tonight,
stratus should return to the Monterey Bay terminals, the question
will be when. Some of the more ambitious models have it around
sunset, while others hold off until after midnight. MVFR conditions
would be expected with the stratus though it should clear out
shortly by mid to late morning.
&&

.MARINE...
(Today through Thursday)
Issued at 930 AM PDT Sat Oct 4 2025

Fresh breeze across the waters, with near gale force gusts for the
offshore waters north of Pigeon Point. Winds will gradually
subside through the weekend. This will translate to steep and
rough seas up to 10 feet resulting in hazardous boating
conditions. Winds continue to ease into next week with light winds
persisting across the waters through the work week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 AM PDT Sunday for Pt Arena to Pt
     Reyes 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm.

     Small Craft Advisory from 3 PM this afternoon to 3 AM PDT Sunday
     for Pigeon Pt to Pt Pinos 0-10 nm.

     Small Craft Advisory until 3 PM PDT Sunday for Pt Arena to Pt
     Reyes 10-60 NM.

     Small Craft Advisory until 9 AM PDT Sunday for Pigeon Pt to Pt
     Pinos 10-60 NM.

&&

$$

SHORT TERM...Flynn
LONG TERM....Flynn
AVIATION...KR
MARINE...KR

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