737
FXUS66 KMTR 141150
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
450 AM PDT Tue Oct 14 2025

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 236 AM PDT Tue Oct 14 2025

 - Post-frontal rain showers and up to a 15% chance for
   thunderstorms today

 - Warming and drying trend Wednesday through Saturday

 - Unsettled weather returns Sunday

&&

.SHORT TERM...
Issued at 236 AM PDT Tue Oct 14 2025
(Today and tonight)

All signs point to rain shower/thunderstorm activity declining
through the day as the surface low pressure system and it`s
attendant cold front (as well as it`s mid-to-upper level support)
will weaken and exit the region through the day. There will still be
chances for rain showers and thunderstorms until the features exit
around midnight. Let`s take a deep dive into the thunderstorm
potential for today by addressing the critical ingredients of lift,
instability, and moisture. In addition to what has already been
discussed lift wise, a 95 knot jet streak from a dive in the Polar
Jet Stream will shift into our region today, which could allow for
more ascent. Instability will be characterized by low CAPE (500
Joules/kilogram) and conditionally unstable lapse rates (7 degrees
Celsius/kilometer). Moisture will ebb and flow throughout the day
and will be highly dependent upon the placement of the surface low
pressure system. A solution over the water will be more moist than a
solution inland which will be capable of entraining drier air into
the system. With similar ingredients on tap for today as what was
present yesterday, I would be very surprised if today outperformed
yesterday given the very limited amount of lightning that was
observed. The best chances for thunderstorms (up to 15%) are for
Southern Monterey and San Benito Counties and the adjacent waters.
Thunderstorm or not, cells will still be capable of producing
locally heavy rainfall resulting in nuisance/urban flooding,
erratic/gusty winds, small hail, and waterspouts. Caution should
continue to be exercised through the day when driving. Roads will
still be wet for this morning`s commute so please allow extra
patience, space, and time when driving, especially for super
commuters who will undoubtedly be driving in the dark. Remember:
turn around, don`t drown! This system is also a cold one. Calm,
clear, and cold conditions tonight will yield near-freezing
temperatures for far interior Monterey and San Benito Counties east
of Highway 101. In addition to the aforementioned near-freezing
temperatures, patchy frost will be possible in sheltered locations
east of Highway 101 in Monterey and San Benito Counties. While
there`s not great consensus amongst guidance/models, the potential
will be there for fog to develop tonight. The limiting factor will
likely be cloud cover as it would allow for less efficient radiative
cooling.

&&

.LONG TERM...
Issued at 236 AM PDT Tue Oct 14 2025
(Wednesday through Monday)

Global ensemble clusters are in agreement that upper-level shortwave
ridging will nose in from the Eastern Pacific Ocean by Wednesday. At
the surface, high pressure will also nose in from the Eastern
Pacific Ocean and build into the Pacific Northwest through Thursday.
This will translate to a northerly (drying) gradient developing
across California. By Friday and into Saturday, the high pressure
builds into the Great Basin while a coastal trough develops off the
coast of California. This will result in light offshore flow for
these two days. Fortunately, just coming off the heels of a
widespread wetting rain event, this warming and drying trend will
not be a fire weather concern. Global ensemble clusters are in
agreement that heights will fall Sunday with an approaching upper-
level longwave trough. Confidence quickly plummets by Monday as
there is near split percentages on if troughing will continue to dig
into the region or if high pressure will rebuild. Nonetheless, at
least expect an increase in cloud cover and wind towards the end of
the forecast. While the current forecast is dry, there is potential
for rain returning to the forecast with ECMWF and GFS total
precipitation ensemble spread showing a three inch disparity.

&&

.AVIATION...
(12Z TAFS)
Issued at 444 AM PDT Tue Oct 14 2025

Pesky spinning low off the coast will keep transient showers/cigs
pivoting through terminals this morning and this afternoon. A mix
of VFR to MVFR conditions are expected, but brief IFR cannot be
ruled out with a heavier showers passing through. Winds for the
most part will be light to moderate. All precip does slowly
diminish Tuesday night.


Vicinity of SFO...VFR mostly with a few pushes of showers later
this morning/early this afternoon, which will bring in some lower
cigs and vis.

SFO Bridge Approach...Same as SFO.

Monterey Bay Terminals...VFR briefing, but MVFR conditions with
rain later this morning.

&&

.MARINE...
(Today through Sunday)
Issued at 444 AM PDT Tue Oct 14 2025

Lingering showers will be possible today as a storm system spins
off the coast. Cannot rule out an isolated thunderstorm south of
Pigeon Point through this afternoon. Hazardous seas will persist
with seas over 10 feet over the outer waters. Overall conditions
will gradually improve late Tuesday into Wednesday.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 PM PDT this afternoon for Pigeon Pt
     to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM.

&&

$$

SHORT TERM...Sarment
LONG TERM....Sarment
AVIATION...MM
MARINE...MM

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