000
FXUS66 KMTR 151822 AAA
AFDMTR

Area Forecast Discussion...UPDATED
National Weather Service San Francisco CA
1022 AM PST Sat Nov 15 2025

...New UPDATE, 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.

&&

.UPDATE...
Issued at 1020 AM PST Sat Nov 15 2025

The only changes to the short term forecast was to update PoPs to
account for ongoing trends. A potent upper low continues to churn
just to the west of the California Bight this morning. Ahead of
this feature, deep southerly flow, as evidenced by regional VWP,
continues to transport rich moisture northward. While our 12Z KOAK
RAOB sampled around 0.82" of precipitable water, satellite-
derived precipitable water indicates a plume of 1.2" to 1.4"
lifting northward into southern portions of Monterey and San
Benito counties this morning. Isentropic ascent along the 296K
theta surface has supported a broad precipitation shield that
continues to expand northward as of this writing.

For the update, PoPs were adjusted to better match the current
radar presentation. The current grids reflect a blend of the HRRR
time-lagged ensemble as well as some experimental Warn-On-Forecast
guidance and recent reports of -RA at Point Lobos provides some
validation for this. Over the next 1-2 hours, widespread rainfall
is anticipated across a good portion of the Central Coast, with
rain arriving across the South Bay between 1pm and 4pm. The
greater Bay Area will likely have to wait until around sunset
before a bulk of the rain activity arrives, with rain impacting
the North Bay during the mid to late evening hours.

Rainfall totals through tomorrow morning are anticipated to
average between 0.75" up to around 2" across the Central Coast.
Across the South Bay, totals will average between 0.5" to near 1"
in/near the higher terrain. The Bay Area and North Bay should
expect between 0.25" and up to 0.5". If out and about today, be
mindful of the potential for ponding, as well as flooding of poor
drainage/low-lying areas.

We`ll continue to examine the potential for a more impactful round
of rain later Sunday and into Monday. More details will follow in
the afternoon forecast update.

&&

.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...
(18Z TAFS)
Issued at 1020 AM PST Sat Nov 15 2025

VFR will eventually yield to poor flying conditions over the next
24 to 30 hours. -RA is anticipated at just about all terminals
during this time period. Slick runways, MVFR visibility and
ceilings are expected to be the main impacts. Intermittent periods
of 2-3 hours without -RA are probable, but uncertainty precludes
getting this hyper-specific in the TAF. Confidence is high that
between 15-17Z Sunday, there will be a break in -RA ahead of the
next storm system slated to increase winds and precip chances
Sunday afternoon and evening.

Vicinity of SFO...Currently VFR with variable winds. -RA and cigs
are anticipated around 22Z, though confidence in timing is low to
medium. By 00Z, VFR cigs are highly probable with -RA resulting in
reduced visibility. While southerly winds are forecast, speeds are
anticipated to remain largely below 10 knots. MVFR cigs and
visibility are forecast a few hours after -RA beings and persist
through a good portion of the TAF cycle. As noted above,
intermittent breaks in -RA are possible, but the most prolonged
period of precip-free conditions appears to be at or after 15Z
Sunday. SHRA INFOV the terminals is anticipated by 21Z Sunday,
with additional SHRA beyond the 30 hour TAF period.

SFO Bridge Approach...Cigs around FL045 are anticipated around
22Z with cigs below FL040 by 00Z. Cigs are probable to persist
through the entire 30 hour period.

Monterey Bay Terminals...-RA has arrived at KMRY and should
arrive at KSNS soon. Cigs continue to lower with variable winds
eventually becoming easterly. -RA should support deteriorating
cigs through this afternoon and evening. Around 4Z/5Z, there is
likely to be a 5-6 hour window of precip-free conditions before
rain returns just before sunrise Sunday. This round of -RA will
last through mid-morning Sunday. MVFR cigs are forecast to
prevail, though there`s a low chance for IFR at KMRY. After the
mid-morning lull in -RA, the next opportunity (for -RA) is not
anticipated until after 18Z Sunday.

&&

.MARINE...
(Today through Thursday)
Issued at 943 AM PST Sat Nov 15 2025

Widespread rain showers are anticipated today, with hazardous
boating conditions, especially for outer waters near and north  of
Pigeon Point. Sunday will bring moderate to fresh north to NW
winds, moderate seas up to 8 feet, and a 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 into Wednesday. Very high west-
northwesterly swell and hazardous seas return late next 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 until 3 AM PST Sunday for Pt Arena to Pt
     Reyes 10-60 NM.

&&

$$

UPDATE...Bain
SHORT TERM...Kennedy
LONG TERM....Kennedy
AVIATION...Bain
MARINE...Bain

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