147
FXUS66 KMTR 112204
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
304 PM PDT Wed Jun 11 2025

...New SYNOPSIS, SHORT TERM, LONG TERM, MARINE, FIRE WEATHER...

.SYNOPSIS...
Issued at 301 PM PDT Wed Jun 11 2025

Stratus returns to portions of the Bay Area and Central Coast
overnight with coastal drizzle likely tomorrow. Breezy afternoon
onshore winds continue through the forecast period with highs
lingering in the 70s to 80s and into the 90s across the far
interior regions for much of the forecast period.

&&

.SHORT TERM...
(This evening through Thursday)
Issued at 301 PM PDT Wed Jun 11 2025

Stratus has mostly receded offshore except along the coastlines of
Marin and San Mateo Counties where some continues to linger. This
retreat will be fairly short lived with stratus returning to
portions of the Central Coast and Bay Area again this evening. The
marine layer looks to remain around 2000 ft again tonight which
would support stratus pushing into the Central Coast and San
Francisco Bay shoreline region. However, cloud cover is expected to
be slightly more limited tonight than it has been over the previous
days with high resolution guidance keeping the North Bay clear
tonight. One reason for this is that a weak passing shortwave trough
allowed the marine layer to deepen to around 2300 ft last night (as
seen on the 12Z OAK sounding this morning) which allowed stratus to
penetrate deep into the Bay Area. This shortwave trough has since
exited the region with more zonal flow returning as high pressure
builds over the Intermountain West. In terms of stratus clearing, it
has been trending slightly earlier in the morning each day this
week. This same trend looks to hold true tomorrow with stratus to
clear by mid to late morning across the region. This earlier
clearing of stratus will help to increase confidence that sites will
reach their forecasted high temperatures across the region. This is
unlike Monday and Tuesday where prolonged stratus coverage decreased
the amount of solar radiation able to reach the surface and kept
temperatures much cooler than originally forecast. High temperatures
on Thursday will be slightly warmer than those observed today with
highs in the upper 70s to upper 80s across the interior and in the
60s to low 70s closer to the coastline. Breezy afternoon winds
between 20 to 30 mph are expected across mountain gaps/passes and
across the higher terrain this afternoon/evening and again Thursday
afternoon/evening. Conditions are drying out across the interior
which in combination with breezy afternoon/evening winds may result
in an increased risk of grass fires - see Fires Section below -
through the weekend. &&

.LONG TERM...
(Thursday night through next Tuesday)
Issued at 301 PM PDT Wed Jun 11 2025

Things remain fairly quiet through the extended with zonal flow to
very weak ridging persisting Friday into the weekend. This will keep
the forecast across the interior fairly similar to what we have
already seen this week with highs in the 70s to low 80s and mid 60s
to low 70s along the coastline. The interior Central Coast will
remain warm through the weekend with highs in the 80s to low 90s.
The main question continues to be the progression of a weak upper
level trough (low pressure) through the Bay Area Sunday evening into
Monday. Model guidance has slowed down the troughs arrival slightly
and pushed into later into Monday with the trough exiting the region
late Monday into early Tuesday. Cluster guidance does indicate a
chance for the trough to persist through Tuesday but that scenario
seems unlikely. Temperatures will remain in the upper 70s to low 80s
across the interior on Monday before a warm up begins Tuesday with
temperatures reaching into the upper 80s to low 90s. Diurnally
breezy to gusty onshore winds continue across mountain gaps/passes,
elevated terrain, and portions of the coastline through the end of
the forecast period. Highest confidence is in gusts between 20 to 30
mph with funneling in gaps/passes potentially resulting in isolated
stronger gusts.

&&

.AVIATION...
(18Z TAFS)
Issued at 1036 AM PDT Wed Jun 11 2025

Solid marine layer this morning with bases hovering around 1500 ft
and tops hovering around 2000 ft. Clearing of inland clouds was
slow going, but since 17Z a trend of clearing has commenced. That
being said, some of the clearing hold outs will be HAF,SFO,OAK
where a solid onshore feed remains. Do expected VFR all terminals
except HAF this afternoon. Onshore flow ushers cigs back in early
tonight. The tricky part is NE flow developing across the N Bay
keep some cigs out of STS and APC. Onshore flow will also lead to
some gusts GT 25kts for SFO and OAK.

Vicinity of SFO...Solid feed through the Gap will keep cigs
lingering through the 19-20Z time frame. Current TAF will shoot
for 20Z, but there is a 30% chc for earlier clearing. Cigs come
in tonight in the 04-06Z timeframe.

SFO Bridge Approach...No feed impacting approach. VFR.

Monterey Bay Terminals...VFR at SNS and MRY will be there shortly.
VFR this afternoon. Early return this evening.

&&

.MARINE...
(Tonight through next Monday)
Issued at 301 PM PDT Wed Jun 11 2025

Northwesterly winds will continue over the coastal waters heading
into the weekend. Winds will increase Wednesday night leading to
locally hazardous conditions with occasional gale force gusts
developing near Point Reyes and south of Point Sur. Moderate to
rough seas will prevail through the week.

&&

.FIRE WEATHER...
Issued at 301 PM PDT Wed Jun 11 2025

While the marine layer will remain in some capacity over the next
few days, what happens above the marine layer is more of a fire
weather concern.  The last night or two have featured moderate to
poor recoveries above the marine layer and that will continue
Thursday night and Friday.  In fact, some locations are hitting
single digit and lower teens for RH values. Hi-res models even t
indicate a burst of NE flow late tonight into early Thursday over
the N Bay. Not overly strong, but this will further enhance any
drying.  There is some quote, recovery, during the daytime, but
another factor comes in. The breezy onshore flow.  Winds will remain
breezy each afternoon/evening through the Delta, and any inland gap
or pass.  The combination of dry fine fuels (grasses), lower RH,
breezy winds with gusts in the 20-40 mph will elevate fire weather
concerns. &&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 AM PDT Thursday for SF Bay N of Bay
     Bridge.

     Small Craft Advisory until 9 PM PDT this evening for Mry Bay.

     Small Craft Advisory until 9 AM PDT Friday 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-Pt Pinos to Pt Piedras Blancas 0-10 nm.

     Small Craft Advisory until 3 AM PDT Friday for Pigeon Pt to Pt
     Pinos 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.

&&

$$

SHORT TERM...Kennedy
LONG TERM....Kennedy
AVIATION...MM
MARINE...MM

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