San Jose, California Weather Forecast Discussion

373
FXUS66 KMTR 051843
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
1143 AM PDT Fri Sep 5 2025
...New AVIATION...
.KEY MESSAGES...
Updated at 1214 AM PDT Fri Sep 5 2025
- A gradual cooling trend continues into next week.
- Chance for light rain early next week.
&&
.UPDATE...
Issued at 922 AM PDT Fri Sep 5 2025
Stratus is starting to recede across the interior with cloud cover
likely to dissipate by late morning into the early afternoon. Some
coastal drizzle was observed this morning with several sites across
the Bay Area reporting one to two hundredths of drizzle this
morning. Otherwise, the forecast remains on track with high
temperatures in the 70s to mid 80s across the interior and 60s along
the coastline.
&&
.SHORT TERM...
Issued at 1214 AM PDT Fri Sep 5 2025
(Today and tonight)
A deep marine layer is bringing extensive stratus coverage across
the CWA. Some measurable drizzle has been reported along the
North Bay coast, with more to come through the morning. The
overall pattern is dominated by a slow moving trough off the coast
that will bring a cooling trend with continued marine layer
clouds and coastal drizzle Saturday morning.
&&
.LONG TERM...
Issued at 1214 AM PDT Fri Sep 5 2025
(Saturday through Thursday)
The pattern is dominated by a building trough off the coast
through the middle of next week. There is a competing ridge over
northern Mexico that will likely make some impact this weekend
before troughing takes back over. As this trough slowly deepens
and pushes closer to the coast, 850 temps will fall from 21C
(75th percentile) measured on the latest balloon, to around 12C
(10th percentile) by Tuesday. Moisture will also be higher than
normal with a notable push of PW over 1" on Monday followed by an
early season cold front and upper level trough axis on Tuesday.
This combination will bring a good chance for light rain,
especially to the North Bay, starting Monday. There is also a
slight chance for stronger convection or even thunderstorms when
the cold upper air moves in on Tuesday. Model support is meager at
the moment, but the ingredients are there and it`s worth keeping
an eye on. The chance for precipitation is increasing, but exact
amounts remain uncertain. Most likely we`ll see a few locations
north of Golden Gate record 1/10" or more, with more novelty rain
further south. There is more confidence is the temperature
forecast, with highs dropping 5-10 degrees below normal by early
next week.
&&
.AVIATION...
(18Z TAFS)
Issued at 1143 AM PDT Fri Sep 5 2025
Inland CIGs are eroding, leading to widespread VFR into the mid
afternoon for all but the immediate coast and HAF which looks to
keep MVFR CIGs. Winds increase into the afternoon, becoming moderate
to breezy. These winds reduce into the evening as CIGS begin to move
inland and lower to IFR levels at HAF. Expect IFR/MVFR CIGs to build
around the bays in the evening and spread farther inland further
into the night with widespread CIGs and light winds expected into
the late night. Expect similar clearing to slightly earlier clearing
times for Saturday.
Vicinity of SFO...Cloud cover erodes into the mid afternoon as
breezy winds build and gusts begin to peak around 23 kts. Cloud
cover returns in the mid evening and fills at SFO as winds reduce
and become moderate. MVFR CIGS stay in place through all of Saturday
morning, but VFR returns around noon as breezy west winds build and
cloud cover exits.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...VFR lasts through the early evening. Winds
are increasing, becoming moderate to breezy. Expect winds to reduce
in the early evening as IFR/MVFR CIGs fill over the terminals and
move inland. These CIGs erode in the late morning and
early afternoon for Saturday as moderate winds build.
&&
.MARINE...
(Today through Wednesday)
Issued at 922 AM PDT Fri Sep 5 2025
Moderate northwesterly winds continue into the weekend with
locally strong gusts along the coastal jet along Big Sur.
Northwesterly breezes will be gentle to moderate this weekend and
into early next week. Moderate seas will prevail through Tuesday.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 AM PDT Saturday for Pt Pinos to Pt
     Piedras Blancas 0-10 nm.
&&
$$
SHORT TERM...Flynn
LONG TERM....Flynn
AVIATION...Murdock
MARINE...Murdock
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NWS MTR Office Area Forecast Discussion