FXUS66 KMTR 140602
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1102 PM PDT Thu Aug 13 2026

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

.KEY MESSAGES...
Updated at 1101 PM PDT Thu Aug 13 2026

 - Well below normal temperatures with a deep marine layer and 
   a chance for drizzle Friday

 - Gradual warming trend kicks off Saturday with temperatures 
   slightly below normal into next week

&&

.SHORT TERM...
Issued at 1101 PM PDT Thu Aug 13 2026
(Tonight through Saturday)

Upper-level shortwave troughing will bring the coolest conditions of 
the week with well below normal temperatures and a deep marine layer 
Friday. The 00Z sounding observed a marine layer of 2,400 feet with 
satellite already showing an inland intrusion through the Delta and 
Pacheco Pass. With the associated lift from the aforementioned 
trough, drizzle can be expected along the coast and in the higher 
terrain via orographic lift. Smoke from the Timber Fire is expected 
to improve with the help of northwesterly transport winds.

&&

.LONG TERM...
Issued at 1101 PM PDT Thu Aug 13 2026
(Saturday night through next Thursday)

Gradual warming trend kicks off Saturday as upper-level ridging 
builds into the Desert Southwest. Simultaneously, upper-level 
troughing will develop well off the West Coast. This will keep the 
ridge in check and onshore flow in place with temperatures remaining 
below normal. The marine layer will likely be deeper in the Bay Area 
than in the Central Coast with a chance for drizzle remaining across 
the coast and higher terrain. Global ensemble clusters are in 
agreement through Tuesday and then by Wednesday 60% show troughing 
prevailing into Thursday. Sensible weather wise, this would result 
in a cooling trend with increased onshore flow and the deepening of 
the marine layer.

&&

.AVIATION...
(06Z TAFS)
Issued at 959 PM PDT Thu Aug 13 2026

MVFR-IFR stratus is expanding across the region and will impact all 
terminals overnight. Lingering southwesterly breezes will gradually 
diminish through the next few hours. Stratus is not expected to 
dissipate until early Friday afternoon, around 19-21Z for most 
terminals. Low to moderate confidence that more northwesterly flow 
will develop Friday afternoon and evening, with moderate to high 
confidence that stratus will again develop across the region on 
Friday evening, with moderate confidence on the exact timing. 

Vicinity of SFO... MVFR ceilings arrive imminently and persist into 
the early afternoon on Friday. Light to gentle southwest winds 
persist overnight into Friday morning. Low to moderate confidence 
that winds will turn more towards the west or west-northwest on 
Friday afternoon and evening, with moderate confidence in stratus 
returning to the terminal sometime Friday evening to Friday night, 
although confidence in timing is low to moderate.

SFO Bridge Approach... Similar to SFO.

Monterey Bay Terminals... MVFR conditions persist through the 
overnight hours with some IFR ceilings possible at MRY. Light winds 
persist overnight before a moderate confidence forecast for more 
northwesterly flow develops Friday afternoon. Low confidence in a 
brief scattering out of the stratus clouds Friday afternoon a couple 
of hours in the afternoon before stratus returns early Friday 
evening.

&&

.MARINE...
(Tonight through next Wednesday)
Issued at 959 PM PDT Thu Aug 13 2026

Gentle to moderate west-northwest winds persist into the weekend
and  early next week as seas continue to subside to moderate in
response.  A long period southerly swell of about 16 to 18 seconds
approaches  the coast Friday night into Sunday. Winds will build
to a fresh northwest breeze early next week, causing seas to build
up to 9  feet. Light drizzle is possible across the coastal
waters. Haze  and smoke may also impact visibility along the Big
Sur coastline  due to the Timber fire.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&

$$

SHORT TERM...Sarment
LONG TERM....Sarment
AVIATION...DialH
MARINE...DialH

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Prepared by Boulder-Creek.com Weather at: Fri Aug 14 00:30:02 PDT 2026