827
FXUS66 KMTR 120457
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
957 PM PDT Fri Jul 11 2025

...New AVIATION...

.KEY MESSAGES...
Updated at 1242 PM PDT Fri Jul 11 2025

 - Moderate HeatRisk across portions of interior Bay Area today

 - Cool trend starts this weekend

 - Gusty onshore winds through gaps in terrain each afternoon may
   cause any grass fires to run

&&

.UPDATE...
Issued at 903 PM PDT Fri Jul 11 2025

Satellite imagery shows stratus along the coastline south of Fort
Ross, passing through the Golden Gate into the Berkeley-Richmond
area, and expanding through the Monterey Bay region and down into
the Salinas Valley. High level smoke from the wildfires in
northern California made for some brilliant sunsets this evening.
This is due to the enhanced scattering provided by smoke particles
in the lower atmosphere as the sun sets, enhancing the red color
of the sun as it sets towards the west. For now, no changes to the
forecast.

DialH

&&

.SHORT TERM...
Issued at 1242 PM PDT Fri Jul 11 2025
(This evening through Saturday)

It is really hard to choose any other ways to describe our weather
than Goldilocks weather. It is simply just right, as far as
summer weather goes. The afternoon satellite imagery shows a pile
of low clouds along the immediate coast, with a nice eddy north of
Point Reyes. There`s also a low cloud finger trying to thread the
needle of the golden gate, but eroding quickly past Angel Island
due to warm air. In addition to the low clouds at the coast smoke
from the Nor Cal fires is drifting overhead around the Bay Area.
Looking at fire.airnow.gov, it does not look like the smoke is
reaching the ground, but rather the sun combining with pollutants
at the surface are causing moderate air quality in populated
areas. Winds are forecast to become more onshore this afternoon,
all the way through 850 hPa, which should shove the smoke to the
east, but will also bring the low clouds in.

Looking at box and whisker plots around the area, temps tomorrow
start to show a cooling trend with a fairly tight spread on the
box. This gives some confidence that models are catching on to the
pattern well. The caveat is that temps aloft do stay warm,
sitting on top of the onshore marine push. As such, Max T for
Saturday above 500 feet was made by blending the official forecast
with NBM 75th percentile. This brought temps up a few degrees
over the previous forecast.

Beyond this, the pattern remains quiet and, well, Goldilocks
weather like. Just right.

&&

.LONG TERM...
Issued at 1242 PM PDT Fri Jul 11 2025
(Saturday night through next Thursday)

Rinse. Lather. Repeat. Summertime in the Bay Area and along the
central coast can be repetitive and the weekend through next week
looks to be that. An upper ridge will remain near our region, but
a quasi-permenant shortwave trough looks to be embedded in the
ridge right over the Bay Area and Central Coast. This means that
we`ll sit, surrounded by heat, with onshore flow and seasonable to
below seasonable temperatures. If you have friends or family that
live in the other parts of California, expect a text from them
soon asking if they can come stay with you for a bit.

&&

.AVIATION...
(06Z TAFS)
Issued at 957 PM PDT Fri Jul 11 2025

Stratus and fog have slowly filled back in along the coastal North
Bay. Wildfire smoke from northernmost California continues to enter
the mix, smoke may add to reducing surface visibilities in hazy or
foggy conditions in the Bay Area tonight and Saturday morning.
Southward from Point Reyes along the coast the marine layer depth
remains somewhat greater still holding at approximately 1200 feet
and satellite imagery shows stratus and fog coverage is continuous.
Onshore winds will usher stratus and fog /IFR-LIFR/ inland tonight
and Saturday morning. The ACV- SFO northerly pressure gradient is
3.9 mb juxtaposed to a SMX-SFO 2.9 mb and SBA-SFO 2.0 mb southerly
pressure gradient setting up a surface wind pattern favoring weak
and stationary surface troughing over the coastal waters. The onshore
component SFO-SAC 3.2 mb supports onshore winds. A few patches of
light coastal drizzle are possible tonight and Saturday morning.
Farthest inland and across the southern half of the forecast areas
is where VFR will have the best chances to continue.

Stratus, fog, wildfire smoke, patchy light drizzle /IFR-LIFR/
improving to MVFR-VFR by late morning and/or afternoon, while
MVFR-VFR continues farthest inland. Coastal stratus, fog, wildfire
smoke, patchy light drizzle combination returns Saturday night and
Sunday morning.

Vicinity of SFO...Moderate to high confidence VFR continues through
late evening, less confident VFR will hold through Saturday morning.
West to northwest wind at SFO has decreased since earlier in the
evening. High resolution HRRR model shows increasing humidity near
daybreak, for now will leave 06z TAF as VFR. Wind flow within the
surface trough over the coastal waters may help prevent the transport
of stratus, however night-time cooling may make up the difference
allowing for patchy stratus and/or fog development Saturday morning
near daybreak. The marine layer depth remains ~ 1200 feet. VFR for
Saturday with an increasing northwest wind gusting to 25 knots in
the afternoon to mid evening. Current HREF shows stratus mainly
staying on the ocean side of the SF Peninsula to north of the Bay
Bridge to Oakland Airport Saturday evening, with the best chance
of BKN-OVC IFR stratus ceiling early Sunday morning. Will leave
late Saturday night/Sunday morning forecast as scattered stratus
clouds for now in the 06z TAF.

SFO Bridge Approach...Similar to SFO. Otherwise incoming wildfire
smoke may restrict slant range visibility especially at sunset and
sunrise.

Monterey Bay Terminals...Onshore surface winds continue to transport
stratus and fog /IFR-LIFR/ inland this evening. Patchy light drizzle
develops tonight and Saturday morning. Winds mainly onshore 5 to 10
knots tonight and Saturday morning. Conditions improving to MVFR-VFR
by late Saturday morning and afternoon. HREF output shows stratus
/MVFR-IFR/ nearby Saturday evening and night.

&&

.MARINE...
(Tonight through next Thursday)
Issued at 507 PM PDT Fri Jul 11 2025

Strong northerly breezes with gale force gusts and rough to very
rough seas will continue for the far northwestern portion of the
northern outer waters through Saturday. Gusty afternoon and early
evening onshore winds will continue mainly north of the Bay Bridge
each day through the weekend. Elsewhere, a gentle to moderate
breeze with moderate to rough seas will prevail.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 PM PDT Saturday for Pt Arena to Pt
     Reyes 10-60 NM.

&&

$$

SHORT TERM...BFG
LONG TERM....BFG
AVIATION...Canepa
MARINE...Canepa

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