482
FXUS66 KMTR 280434
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
934 PM PDT Wed Aug 27 2025

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 1251 PM PDT Wed Aug 27 2025

 - Temperatures hover near normal through Friday, to slightly above
   normal through the weekend.

 - Quiet weather through the weekend, into beginning of next week.

&&

.UPDATE...
Issued at 609 PM PDT Wed Aug 27 2025

That`s it, our chances of convection are over. The 00Z balloon
just popped and reported much drier air below 700 mb. The PW
dropped from 1.00" at 12Z to 0.69" at 00Z. This brought the MUCAPE
down to a paltry 17 J/kg, with an insurmountable -658 J/kg of CIN.
After nearly 5 days of slim chances for thunderstorms, I am
officially downgrading to zero chance going forward.

While the monsoon moisture has filtered out, there is another
push of moisture moving into southern California tomorrow from the
remnants of Tropical Storm Juliette. This will bring some rain to
San Diego, but there is high confidence that we won`t see any
impact from this moisture. A developing short wave trough will
move quickly through the pattern and drag the vast majority of
the tropical air mass east into the desert. The confidence is so
high that the moisture won`t make it to the Bay Area that I cant
find any guidance that even brings us high clouds.

Finally, the stratus bank has again pulled nearly 100 miles off
the coast this afternoon. This happened yesterday and it took much
longer for marine layer clouds to redevelop over land, if they
ever did. SFO never actually reported a ceiling this morning despite
all model guidance to the contrary. As such, expect similar
delayed clouds returning overnight. Another good evening for
stargazers.

&&

.SHORT TERM...
Issued at 1251 PM PDT Wed Aug 27 2025
(This evening through Thursday)

Quiet weather for the rest of today and into tomorrow as an upper
level low sits off the coast of central and southern CA. This
evening and into tonight, stratus will slowly saunter into the
region with skies clearing by mid to late Thursday morning. Upper
level ridging from the Desert Southwest tries to nose into northern
CA, which should lead to slight increase in high temperatures for
tomorrow.

&&

.LONG TERM...
Issued at 1251 PM PDT Wed Aug 27 2025
(Thursday night through next Tuesday)

Quiet weather will continue into the extended portion of the
forecast as we are caught between upper level troughing over the
eastern Pacific and upper level ridging to our east. Flow looks to
remain zonal or quasi zonal at times, with the main differences
being the temperature. A gradual uptick in high temperatures is
expected Friday and into the weekend, with temperatures faltering
some into early next week. The marine layer has shown some signs of
compressing, which means the stratus may not be as widespread over
the weekend.

&&

.AVIATION...
(06Z TAFS)
Issued at 922 PM PDT Wed Aug 27 2025

Continuing to push the stratus timing back to show deference to
the persistence forecast over aggressive model guidance. The
stratus bank is making a push back to the coastline, but still has
a long way to go, and the coverage looks similar to this time
yesterday.

Vicinity of SFO...While SFO avoided a ceiling yesterday, there
were low clouds along the coast and in the Bay. As such, it`s
still wise to anticipate ceilings in the morning, but the arrival
will be delayed until near sunrise as the cloud bank pushes back
towards to the coast.

SFO Bridge Approach...Similar to SFO

Monterey Bay Terminals...Most guidance suggests the ceilings are
already here, but in reality clouds are nearly 100 miles away
over the Pacific. As a result this forecast is highly uncertain
and leans mostly on the persistence forecast with some hedging
towards the robust signal in the guidance. Based on what happened
yesterday and the current satellite picture, ceilings actually may
hold off until 12Z or later. LAMP and MOS guidance is rarely this
far out of step with reality.

&&

.MARINE...
(Tonight through next Tuesday)
Issued at 922 PM PDT Wed Aug 27 2025

Light to moderate winds and seas continue across the coastal
waters through the end of the week. Seas build and fresh to strong
gusts develop over the weekend bringing hazardous conditions
across the coastal waters into the next work week.

&&

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

$$

SHORT TERM...KR
LONG TERM....KR
AVIATION...Flynn
MARINE...Kennedy

Visit us at www.weather.gov/sanfrancisco

Follow us on Facebook, X, and YouTube at:
www.facebook.com/nwsbayarea
x.com/nwsbayarea
www.youtube.com/nwsbayarea