916
FXUS66 KMTR 102111
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
211 PM PDT Tue Jun 10 2025

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

.SYNOPSIS...
Issued at 207 PM PDT Tue Jun 10 2025

Daily pattern of the return of marine layer clouds overnight
through the morning hours, some coastal drizzle, and breezy
afternoon onshore winds continues for much of this week.
Temperatures remain in the upper 70s to 80s across the interior
for much of this week as the pattern remains fairly quiet.

&&

.SHORT TERM...
(This evening through Wednesday)
Issued at 207 PM PDT Tue Jun 10 2025

"June Gloom" continues to be the predominant theme of the short term
forecast with stratus set to return across much of the CWA tonight
into Wednesday morning. The 12Z OAK sounding shows the marine layer
at a depth of approximately 2000 ft which allowed stratus to filter
into much of the interior Bay Area and Central Coast. A look at the
current temperatures (as of 1 PM) show most sites are mostly on
track with the observed temperatures coming within 1-2 degrees of
the hourly forecast temperature. High temperatures today will
generally be in the mid 70s to 80s across the Bay Area and portions
of the Central Coast. The two caveats to this will be temperatures
for coastal areas will stay in the 60s and temperatures across the
far interior Central Coast will reach the 90s to low 100s. Forecast
guidance from the WRF keeps the marine layer closer to 1000 ft
tonight, however, guidance has consistently been underestimating
marine layer depth for much of this week. Both the ECMWF and GFS
models show a weak upper level shortwave trough moving through
Tuesday night into Wednesday. In terms of forecasting the marine
layer, an upper level low (or in this case a shortwave trough) would
allow the marine layer to deepen while building upper level ridging
or high pressure would serve to compress the marine layer. The
passage of this weak shortwave trough would then support our marine
layer either maintaining a depth around 2000 ft or potentially
deepening slightly and result in stratus spreading across much of
the interior. Given that the marine layer depth is expected to be
around 2000 ft again tonight, confidence is low that fog will
develop but patchy drizzle is possible along the coastline. Stratus
coverage is expected dissipate mid to late morning across the
interior while it looks to stick around through the late morning for
coastal areas. High temperatures on Wednesday will be similar to
today if a few degrees cooler. High temperatures across the interior
Bay Area will be in the 70s to low 80s will high temperatures across
the interior Central Coast will be in the 80s to 90s.

&&

.LONG TERM...
(Wednesday night through next Monday)
Issued at 207 PM PDT Tue Jun 10 2025

Temperatures remain fairly similar Wednesday through the weekend
with highs in the 70s to low 80s across the interior Bay Area and
80s to low 90s across the interior Central Coast as zonal upper
level flow persists. As zonal flow continues, we can expect to see
similar stratus trends for much of this week with stratus returning
during the evening and persisting into the next morning. Confidence
is fairly high for coastal locations but slightly lower for
locations across the interior where a deeper vs shallower marine
layer will dictate how far inland stratus is able to extend. If the
marine layer maintains a depth of around 2000 ft, stratus will
extend farther across the interior. If the marine layer compresses
to a depth of 1000-1500 ft, as guidance suggests is possible,
stratus coverage may not extend across as much of the interior as it
has over the past few days. Upper level ridging looks to briefly
build late week, compressing the marine layer and warming
temperatures by a few degrees, before a weak upper level trough
moves through the Bay Area Sunday into Monday. This will help to
decrease temperatures by 2-3 degrees across the interior from Sunday
to Monday. The real question occurs just beyond the end of our
forecast period with guidance split on if ridging will build over
the West Coast next week or if zonal to weak upper level troughing
will continue. The continuation of zonal flow to weak upper level
troughing would not result in major changes to our current
temperature forecast. However, if upper level ridging is able to
setup temperatures are likely to see a warming trend next week. The
6 to 10 and 8 to 14 day outlooks from the CPC do support
temperatures leaning above normal across the Bay Area and Central
Coast from the middle to end of June.

&&

.AVIATION...
(18Z TAFS)
Issued at 1146 AM PDT Tue Jun 10 2025

.AVIATION...The forecast will be the timing of the status of
the stratus as the forecast has been and will be on repeat. Tended
to trend with observations from today and yesterday for timing of
arrival and departure respectively, assuming we have a similar
marine layer depth. Expect IFR to MVFR cigs at most sites, with
interior locations like KSJC and KLVK clearing the fastest, followed
by North Bay terminals. IFR cigs may get low enough to drop vis MVFR
at times.

Vicinity of SFO...Medium to high confidence in the SFO forecast as
the stratus pattern looks similar to what we saw yesterday, perhaps
slightly stronger for stratus remaining socked in to the east at
KOAK. Expect to have MVFR conditions hold through the period, with
the chance for clouds becoming BKN for a period this afternoon. This
will be short lived as the westerly feed of stratus is strong.
Models generally struggle to capture this, with the HRRR, GLAMP, and
NBM supporting this. Guidance seems supportive of potential clearing
to some degree tomorrow afternoon between 18Z and 0Z. Though stratus
looks to make yet another return after that.

SFO Bridge Approach...The approach should fair better than the
vicinity of SFO as we can see the stratus mixing out over the
southern portion of the bay. The stratus line appears to be holding
right around the vicinity given the continuous westerly flow. Expect
similar conditions to yesterday where visuals will be short lived.

Monterey Bay Terminals...Stratus will continue to hug the coast with
clearing expected around Santa Cruz and the north part of the Bay.
KSNS should see some clearing as well this afternoon based on
persistence forecasting and satellite imagery. Unsure if MTR will be
so lucky, opted to try and trend towards some VFR conditions with a
TEMPO this afternoon. Otherwise expect MVFR to IFR cigs, and reduced
vis with the low cigs.

&&

.MARINE...
(Today through Sunday)
Issued at 238 AM PDT Tue Jun 10 2025

Fresh to strong northwesterly breezes will prevail through the
forecast period with gale force gusts possible beginning Wednesday
afternoon along the coastal jet regions of Point Reyes and Point
Sur. Significant wave heights will be moderate today, building to
become rough tomorrow.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 PM PDT Wednesday for Pt Pinos to Pt
     Piedras Blancas 0-10 nm-SF Bay N of Bay Bridge.

     Small Craft Advisory until 9 PM PDT this evening for Mry Bay-
     Pigeon Pt to Pt Pinos 0-10 nm.

     Small Craft Advisory from 9 AM to 3 PM PDT Wednesday for Mry Bay-
     Pigeon Pt to Pt Pinos 0-10 nm-Pt Arena to Pt Reyes 0-10 nm.

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

&&

$$

SHORT TERM...Kennedy
LONG TERM....Kennedy
AVIATION...KR
MARINE...Sarment

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