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
From the National Weather Service
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