075
FXUS66 KMTR 041103
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
303 AM PST Tue Nov 4 2025

...New SHORT TERM, LONG TERM...

.KEY MESSAGES...
Updated at 257 AM PST Tue Nov 4 2025


 - Wind gusts of 45 to 65 mph are forecast for portions of the
   North Bay, East Bay, SF Bay, and Santa Cruz Mountains.

 - Low potential for nuisance flooding in the North Bay, but
   moderate rainfall will be largely beneficial.

 - Thunderstorm chances remain around 10 to 20 percent with the
   main hazards being pockets of heavier rainfall and enhanced
   outflow winds.


&&

.SHORT TERM...
Issued at 257 AM PST Tue Nov 4 2025
(Today and Tonight)

Quiet weather to start the day today will transition to more
turbulent conditions tonight and into the day on Wednesday. High
clouds continue to filter in overhead across the North Bay and
this should curtail the threat for widespread dense fog (and
perhaps fog in general). Farther south, the lack of mid and upper
level clouds has facilitated more in the way of radiative
cooling and we`re starting to see some sites dip down to 1/2 mile.
Trends will be monitored this morning for a short-fused Dense Fog
Advisory (would be the SC Mountains and Salinas Valley). Fog
should mix out rapidly by mid to late morning.

Our well advertised upper low will inch toward Northern
California through the day. As it does, it`ll induce pressure
falls and tighten the surface pressure/height gradient. In
response, southerly winds will ramp up, especially after 00Z
across marine zones and adjacent coastal regions. Across the
southern Big Sur Coast, there will likely be sufficient ascent for
some WAA convection and after discussion with LOX, opted to add
in some showers.

The largest impact with this system is anticipated to be the
wind. The general timeline for winds will be from roughly 10pm
tonight through 4pm Wednesday. Over the last few days, model
guidance has come into greater agreement with regard to placement
of the greatest corridor of winds will reside. Just about all
deterministic guidance indicates that a belt of 50 to 60 knot flow
will nose in from the southwest across the Sonoma and Marin
Coastline. At the surface, our trusty MTRWRF and PG&E/SJSU WRFs
support surface wind gusts in excess of 60 mph for the Pacific
Coast north of the Golden Gate strait and I`ve upgraded this
region to a High Wind Warning for wind gusts of 60 to 65 mph which
aligns with the corridor of high 925mb winds. Taking an
examination at some the Extreme Forecast Index tools, there`s a
very strong signal that the EPS ensemble forecast distribution is
substantially higher than the model`s climatology. In fact there`s
some indication that a few of the EPS ensemble members are quite
anomalous/extreme. What this translates to is a potential for
65-70mph wind gusts in spots.

Areas south of the Golden Gate are on the fringes of the
aforementioned 925mb jet max, but wind gusts in the 45 to 55 mph
(and thus a Wind Advisory) are advertised for SF, the San Mateo
Peninsula, East Bay, and Santa Cruz Mountains, though it`s not out
of the realm of possibility that some of these areas may need to
be added to the High Wind Warning, especially if the corridor of
strongest winds shifts southward. Regardless of High Wind Warning
or Wind Advisory, individuals should secure any loose outdoor
articles/decor and anticipate driving difficulty for high-profile
and lightweight vehicles (especially on east-west oriented
roadways). In addition, there will be the potential for sporadic
power outages, particularly across the Pacific Coast near/north of
the Golden Gate.


&&

.LONG TERM...
Issued at 257 AM PST Tue Nov 4 2025
(Wednesday through Monday)

Potentially enhancing winds via precipitation loading will be
pockets of moderate to at times heavy rainfall. This will be most
probable across the North Bay where instability is forecast to be
the greatest. In fact, forecast soundings and hi-res NWP indicate
meager, but sufficient amounts of MUCAPE of around 100-250 J/kg
across the North Bay and the thunder potential is largely confined
to this region and adjacent waters. The main hazard with storms
will be bursts of stronger winds and heavier precipitation. While
heavy rainfall is possible, the potential for widespread flooding
appears to be on the low side for a couple of reasons. 1) Near
surface soil moistures are running near or below normal per NASA
SPoRT output, and 2) the progressive nature of this system should
minimize the potential for training thunderstorms. Examination of
experimental flood mapping as well as the Hydrologic Forecast
Ensemble System indicates little to no responses across the main
stem rivers. That said, some of the more heftier precipitation
rates will transpire during the Wednesday morning commute and this
may result in traffic impacts as water mixes with oils in
roadways and ponding/nuisance flooding takes place in urban/poor
drainage areas. Again, the system appears that it`ll remain
progressive and we don`t anticipate a high potential for
stalling/training of precipitation bands.

Overall rainfall amounts remain somewhat consistent with previous
forecast iterations, though there have been some adjustments
upward in the higher terrain/favored coastal regions. North Bay
rain amounts appear that they`ll still average anywhere between
0.50" in the `rain shadowed` areas to the 1-2.5" range across the
higher terrain. Some of the more prominent North Bay Mountains may
be the recipients of more optimal upslope flow with values just
under 3". We`ll need to potentially make some last minute
refinements to QPF as there are some meaningful probabilities of
over 3" amounts across coastal Sonoma County between Sea Ranch and
Bodega Bay. Farther south, rain amounts average between 0.25" to
0.75" across the Bay Area and Central Coast, with amounts over 1"
across the Santa Cruz Mountains, Santa Lucia Range, and Big Sur
Coast.

Precipitation is anticipated to taper off through Wednesday
night. Rapid clearing in the wake of the precipitation and
diminishing winds may set the stage for a decent radiation fog
event, especially across the North Bay where the heaviest rainfall
is anticipated. However, this may be modulated by lingering cloud
cover, wind speeds and/or the amount of dry air that filters in
behind a front.

The weather pattern appears that it`ll remain progressive with
largely zonal flow anticipated as we round out the first full week
of November. There are some hints at a few perturbations rippling
through the flow that may give the North Bay a few opportunities
for additional light rainfall.

&&

.AVIATION...
(06Z TAFS)
Issued at 921 PM PST Mon Nov 3 2025

IFR-LIFR stratus developing across the Monterey Bay region and
lingering along the coast south of Point Sur, with mid-to high level
clouds streaming in through the Bay Area and points north. The
interaction between the coastal stratus and the higher prefrontal
clouds is a complex interaction as the high clouds could interfere
with the radiational cooling that would contribute to fog or low
stratus, decreasing the confidence in the forecast for stratus
formation tonight and dissipation on Tuesday morning. Current best
forecast is for the stratus to expand into the coastal valleys
through the night and retreat to the coastal regions through the
morning. Southerly winds will increase through Tuesday with the
strongest winds developing near or slightly beyond the end of the 24-
hour TAF period. Scattered showers will develop in the North Bay
Tuesday night but the main rain band likewise arrives after the end
of the TAF period.

Vicinity of SFO... VFR at present. Coastal stratus and prefrontal
clouds combine to give the terminal a moderate confidence for MVFR
ceilings in the early part of Tuesday morning, dissipating after
sunrise. The winds will shift to a more south-southwest flow on
Tuesday in advance of the front, which continue to increase through
and beyond the end of the TAF period. Some high resolution models
depict chances for MVFR ceilings during the Tuesday evening
timeframe, but confidence is too low to include in the TAF.

SFO Bridge Approach... Similar to SFO.

Monterey Bay Terminals... IFR-LIFR stratus is developing, currently
impacting SNS and will come over MRY sometime tonight. Local effects
will influence the time of stratus development so the TAF ceiling
forecast is a moderate confidence forecast. Strong southwest winds
will develop at MRY Tuesday afternoon, while confidence is moderate
that winds at SNS develop from the northwest. Winds diminish Tuesday
evening with moderate confidence of radiative fog at MRY that night.

&&

.MARINE...
(Tonight through next Sunday)
Issued at 921 PM PST Mon Nov 3 2025

Moderate breezes across the waters will continue through the night
before increasing on Tuesday, with winds across the waters  to the
north of Point Pinos already coming from the south and  those to
the south gradually shifting to the south through the  night. By
late Tuesday and into Wednesday, near- gale force to  gale force
sustained winds are expected. Widespread gale force  gusts are
expected during this time with isolated storm force  gusts
possible for the northern most waters. Seas will build to  become
very rough for the inner waters and outer waters Wednesday  and
Thursday. Rain showers Tuesday will turn into widespread  rainfall
and a slight chance for thunderstorms Wednesday.

&&

.BEACHES...
Issued at 402 AM PST Mon Nov 3 2025

A long period northwesterly swell will continue to bring an
increased risk for sneaker waves, rip currents, and breaking waves
of up to 20 feet to Pacific Coast beaches today. High surf
conditions are possible, especially at the west and northwest
facing beaches. Remember, 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. Swimmers
should always swim near a lifeguard. Stay off the rocks, remain
out of the water to avoid hazardous swimming conditions, and never
turn your back on the ocean!

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement until 3 AM PST early this morning for
     CAZ006-505-509-529-530.

     Coastal Flood Advisory from 8 AM this morning to 2 PM PST
     Saturday for CAZ006-506-508-529-530.

     Wind Advisory from 10 PM this evening to 4 PM PST Wednesday for
     CAZ006-503-504-506-508>510-512-515.

     High Wind Warning from 10 PM this evening to 4 PM PST Wednesday
     for CAZ502-505.

PZ...Small Craft Advisory from 3 PM this afternoon to 9 PM PST this
     evening for Pigeon Pt to Pt Pinos 0-10 nm-Pigeon Pt to Pt
     Pinos 10-60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm-Pt
     Reyes to Pigeon Pt 0-10 nm-SF Bay N of Bay Bridge.

     Gale Watch from this evening through Wednesday afternoon for
     Pigeon Pt to Pt Pinos 0-10 nm-Pt Pinos to Pt Piedras
     Blancas 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm-SF Bay N of
     Bay Bridge.

     Small Craft Advisory from 9 PM this evening to 3 PM PST
     Wednesday for Mry Bay.

     Small Craft Advisory from 9 AM this morning to 9 PM PST this
     evening for Pt Arena to Pt Reyes 0-10 nm.

     Gale Watch from this evening through Wednesday morning for
     Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm-
     Pt Arena to Pt Reyes 10-60 NM.

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

&&

$$

SHORT TERM...Bain
LONG TERM....Bain
AVIATION...DialH
MARINE...DialH

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