812
FXUS66 KMTR 121020
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
320 AM PDT Sat Jul 12 2025

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

.KEY MESSAGES...
Updated at 318 AM PDT Sat Jul 12 2025

 - A cooling trend begins this weekend.

 - Localized elevated fire weather threat continues across higher
   elevations.

&&

.SHORT TERM...
Issued at 318 AM PDT Sat Jul 12 2025
(Today and tonight)

Stratus has returned and is more widespread this morning, as it can
be seen creeping into the Bay Area valleys. Expect it to continue to
slowly seep into the valleys some more and then retreat back to the
coast by mid to late morning. Cloudy skies should hold along our
coast, while skies are sunny for interior locations for the
afternoon. Stratus will surge inland again this evening, with
valleys filling overnight. Look for near seasonal high temperatures
inland, and near to below normal temperatures along the coast or
stuck underneath the stratus.

&&

.LONG TERM...
Issued at 318 AM PDT Sat Jul 12 2025
(Sunday through Friday)

The forecast will be on repeat for the extended period. An upper
ridge will surround much of the region, but a quasi-permenant
shortwave trough looks to be embedded in the ridge right over the
Bay Area and Central Coast. This should lead to onshore flow and
cooler weather with temperatures near or below normal for this time
of year.

&&

.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...
(Today through Thursday)
Issued at 318 AM PDT Sat Jul 12 2025

Fresh northerly breeze and rough seas over the northern outer
waters through today. Gusty afternoons onshore winds continue
through the weekend. Winds over the outer waters diminish
gradually through the weekend. Otherwise, moderate seas persist.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 9 AM PDT this morning for Pt Arena to
     Pt Reyes 10-60 NM.

&&

$$

SHORT TERM...KR
LONG TERM....KR
AVIATION...Canepa
MARINE...Behringer

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