308
FXUS66 KMTR 102330
AFDMTR

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

...New AVIATION...

.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...
(00Z TAFS)
Issued at 430 PM PDT Tue Jun 10 2025

The forecast looks very similar to the last couple of days with
stratus building inland during the evening and overnight hours
before retreating to the coastal regions in the morning and
afternoon. Have opted to continue with a generally persistent
forecast for the terminals as the daily patterns have remained
rather consistent. If the marine layer does compress at any point,
less stratus intrusion inland and earlier clearing times Wednesday
morning would be the result. MVFR-IFR conditions are generally
expected overnight with some LIFR ceilings possible at the immediate
coast. Inland terminals will be the first to clear Wednesday
morning, followed by the North Bay.

Vicinity of SFO... After a brief clearing at the terminal, MVFR-IFR
stratus has returned and should persist through the overnight
period. Westerly winds remain breezy and gusty through the evening
hours with gusts abating overnight before picking up again Wednesday
afternoon. Moderate confidence in a period of scattering at the
terminal sometime between 18-00Z Wednesday, with stratus returning
sometime afterward. However, confidence is lower in stratus
returning before the end of the TAF period. the SCT group starting
at 03Z Wednesday evening accounts for the possibility. Greater
confidence in stratus return timing at OAK, where conditions return
to BKN at the same timeframe.

SFO Bridge Approach... The approach path should remain clear for a
couple more hours. However, visual approaches may be lost by around
02-03Z as stratus builds south from the terminal. For Wednesday
morning, higher confidence that the approach path clears before the
terminal does, with westerly flow potentially keeping a stratus feed
right at the edge of SFO.

Monterey Bay Terminals... MVFR-IFR stratus persists through the
evening before dropping to LIFR overnight. Highest confidence for
clearing stratus Wednesday morning along the northern side of the
Monterey Bay. Moderate confidence for clearing at SNS with lower
confidence for the exact timing, as high resolution models suggest
an earlier clearing time than a persistence forecast. Lower
confidence for the scattering of stratus at MRY.

&&

.MARINE...
(Tonight through next Sunday)
Issued at 308 PM PDT Tue Jun 10 2025

Moderate to fresh northwesterly winds are expected for today, with
the potential for some strong breezes across the waters. Winds
become fresh to strong tomorrow with near 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 Arena to Pt
     Reyes 10-60 NM-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.

&&

$$

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

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