697
FXUS66 KMTR 151136
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
336 AM PST Sat Nov 15 2025

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 249 AM PST Sat Nov 15 2025

 - Unsettled, rainy weather conditions with multiple systems set
   to arrive this week.

 - Gustier winds return Sunday into Monday.

 - Noticeably cooler conditions late weekend into next week.

&&

.SHORT TERM...
Issued at 249 AM PST Sat Nov 15 2025
(Today and tonight)

Current observations show clear skies and dry conditions across the
majority of the CWA as of 1 AM PST. However, this is set to change
shortly with KMUX showing precipitation echoes on the verge of
entering Monterey/San Benito Counties. Satellite shows a wider area
of cloud cover and stratiform rain to our south off the coast of
Southern California. This feature will progress northwards through
the rest of today and bring us another round of rain. High
resolution guidance from the HRRR shows rain reaching southern
Monterey and San Benito Counties by 6 AM PST and spreading northward
into the Central Coast during the morning hours. Showers will reach
the South Bay and Santa Cruz County by late morning/early afternoon
with scattered showers spreading into the rest of the Bay Area
during the afternoon. Given the south to north progression of the
stratiform rain, the highest precipitation totals this time will be
in the Central Coast (1-2.5") with between 0.5-1.0" for Santa Cruz
County and the majority of the Bay Area. The North Bay looks to
receive the lowest amounts of precipitation with totals between 0.25-
0.5". High temperatures today will be in the 50s to low 60s across
the Central Coast and 60s to low 70s across the Bay Area.

The Extreme Forecast Index is highlighting a substantial
portion of the Central Coast (in addition to Southern California and
the Central Valley) for extreme rainfall today. For our CWA, this is
mainly a concern for Monterey and San Benito Counties where the
heaviest rainfall is expected. If we see a stronger surge of
moisture we may see rainfall totals closer to the 90th percentile of
2.5-3" across the Central Coast today. The Santa Lucia Range saw
between 3-6" of rain from our last system with another 1.5-2.5"
expected today. Given that soils are likely still saturated, we may
see some localized nuisance flooding across the Central Coast today.
A marginal risk (5%) of excessive rainfall leading to flash flooding
has been issued for the Central Coast today with a slight risk (at
least 15%) for far southeastern Monterey County in the vicinity of
Parkfield. Thunderstorm chances are fairly contained to the interior
Central Coast today where there is a 10-15% chance of thunderstorms.
While we do have some MUCAPE (100-200 J/kg) and slightly
conditionally unstable 700-500 mb lapse rates across the interior
Central Coast, confidence is low that thunderstorms will develop.
The main area of lift associated with the cut-off upper level low
will be well to our south where thunderstorm conditions are more
favorable over Southern California.

&&

.LONG TERM...
Issued at 249 AM PST Sat Nov 15 2025
(Sunday through Friday)

Scattered, light showers continue on Sunday before more widespread
rain returns Sunday night into Monday morning. More widespread rain
returns as a result of a deep upper level trough pushing into the
West Coast and forcing the cut-off low over Southern California to
progress east. Most interior areas will see between 0.5-1.0" while
the coastal mountain ranges will see between 1-2". Locally higher
totals are possible in the Santa Cruz Mountains and Santa Lucia
Range. Higher end scenarios (NBM 90th percentile) more widespread
totals between 1.5-3" are possible. A marginal risk (5%) of
excessive rainfall leading to flash flooding has been issued for
Sunday across our entire county warning area. Given that this will
be our third system within a short time frame, soils are likely
already or will be saturated by the time this system arrives. With
that in mind, we are likely to see an uptick in nuisance flooding
particularly in areas that have received heavy rainfall recently. If
you encounter flooding on roadways, do not drive through it instead
turn around, don`t drown. Winds are expected to strengthen Sunday
into Monday which, in combination with saturated soils, may result
in downed trees or power lines across the area. While the winds are
expected to be weaker than what we saw last week, we are still
looking at gusts between 30 to 40 mph with locally stronger gusts in
favored areas. The Storm Prediction Center has issued a general
mention of thunderstorms for portions of the Bay Area and Central
Coast on Sunday. Thunderstorm chances will be highest Sunday evening
into early Monday when frontal passage is set to occur. High
resolution guidance shows some MUCAPE, lapse rates around 7 C/km,
and decent low level shear with cold frontal passage to act as a
source of lift. If this system does slow down, we may see a shift to
early Monday for the highest thunderstorm chances compared to late
Sunday.

In the wake of our Sunday-Monday system, the region will dry out and
a much cooler air mass will move in as ridging builds in. 850 mb
temperatures showcase this cold airmass well with 850 mb
temperatures forecast to be around 0C-3C for much of this week. For
context, the SPC sounding archive shows the minimum 850 mb
temperatures for mid November are around -2C to -1C with
temperatures in the 0C-2C range in the bottom tenth percentile. What
are we looking at temperature wise? High temperatures will
effectively stay in the 50s to low 60s through late this week.
Mornings will get progressively chillier starting Sunday with low
temperatures dropping into the 40s region wide. The higher
elevations and interior Central Coast will be particularly chilly
with lows dropping into the low to mid 30s. By late next week,
another upper level trough looks to arrive late Wednesday with
widespread rain continuing through Friday. While we are too far out
to discuss the exact details of this system, it is worth keeping an
eye on as our unsettled pattern and wet start to the rainy season is
set to continue.

&&

.AVIATION...
(12Z TAFS)
Issued at 323 AM PST Sat Nov 15 2025

VFR conditions persist across the terminals early this morning.
There is a chance STS gets hit with mist or fog, but the winds
have been just strong enough to keep the visibility unrestricted
for now. Through the TAF period MVFR ceilings and light rain
showers will move in from the south. This system will also bring
shifting wind directions as it approaches the terminals.

Vicinity of SFO...Currently VFR with increasing mid level clouds
and a gentle northerly breeze. While overcast skies will persist,
there is only a slight chance of ceilings dropping below 3,000
feet today. There is a much better chance overnight into Sunday
as the light rain moves in from the south. Winds will remain light
through the morning with a few hours of moderate onshore winds in
the afternoon.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Since the rain is moving in from the
south, the Monterey Bay terminals are first in line. While the
TAFs don`t bring rain in until 21Z, there may be a light shower
or two before the more consistent rain starts. Drainage winds will
flip back onshore this afternoon before synoptic forcing shifts
them southerly this evening.

&&

.MARINE...
(Today through Thursday)
Issued at 323 AM PST Sat Nov 15 2025

Sunday will bring moderate to fresh north to NW winds, moderate
seas up to 8 feet, and a few rain showers. A storm will bring
strong to near gale force northerly winds Sunday night, quickly
building very rough seas by Monday morning. Conditions will
gradually improve Tuesday-Wednesday. Very high WNW swell moves in
late week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 3 PM this afternoon to 9 PM PST this
     evening for Pt Arena to Pt Reyes 0-10 nm.

     Small Craft Advisory from 9 AM this morning to 3 AM PST Sunday
     for Pt Arena to Pt Reyes 10-60 NM.

&&

$$

SHORT TERM...Kennedy
LONG TERM....Kennedy
AVIATION...Flynn
MARINE...Flynn

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