689
FXUS66 KMTR 171030
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
330 AM PDT Thu Jul 17 2025

...New KEY MESSAGES, SHORT TERM, LONG TERM...

.KEY MESSAGES...
Updated at 235 AM PDT Thu Jul 17 2025

 - Below seasonal temperatures continue through Thursday before a
   slight warming trend begins Friday into the weekend.

 - Localized elevated fire weather threat continues across the
   higher elevations with drier conditions beginning this weekend.

 - Increasing winds early next week.

&&

.SHORT TERM...
Issued at 240 AM PDT Thu Jul 17 2025
(Today and tonight)

We`re more than halfway through the month and "No Sky July"
remains locked in. Current overnight satellite fog product shows
another robust marine layer blanketing the coastal waters and
inland valleys. Fort Ord profiler indicates the depth of the
marine layer actually increasing a little since Wednesday. The
slight deepening is likely due to a weak/subtle upper level
shortwave trough over NorCal coast. The deeper marine layer was
just enough to hamper another "drizzle-fest" along the coast.
We`ve had one gage tip since midnight, which is less than 24
hours ago. That being said, will still carry some patchy drizzle
in the forecast for the coast Thursday morning. Morning clouds
will give way to inland sunshine. Despite some inland sunshine
temperatures will still be seasonably cool for July with highs
reaching the upper 50s to near 70 for the coast and 60s to lower
90s inland -- or about 5 to 10 degrees below normal for July.
Speaking of below normal - July 1 through July 16 has shown high
temperatures on average are 1 to 3 degrees below normal. Who
remembers July of 2024? If you do, it was so much warmer than
2025. Temperatures on average for the whole month of July were 2
to 4 degrees warmer than average with inland areas 6 to 8 degrees
warmer.

Expect similar conditions again Thursday night into Friday - solid
marine layer with some patchy coastal drizzle.

Previous discussion highlighted fire weather concerns above the
marine layer and those concerns remain early Thursday morning.
Dry and mild conditions remain at 2000 feet and above with
temperatures in the 60s to lower 70s with poor humidity less than
30%.

&&

.LONG TERM...
Issued at 328 AM PDT Thu Jul 17 2025
(Friday through Wednesday)

While we`re talking about seasonably cool July so far we will see
some warming in the long term. Interesting longwave pattern over
CA Friday and into the weekend. Two upper lows continue to spin
with one retrograding off the NorCal coast and the other is move
through N Baja/SoCal. In between is a squeezed upper level ridge.
This ridge will result in higher 500mb heights, warmer 850mb
temps, and a slightly more compressed marine layer. As such, a
slight uptick in temperatures can be expected Friday and over the
weekend. Temperatures through this period will warm 3 to 5
degrees each day with far inland areas reaching the mid to upper
90s. Daytime temperatures will warm, but overnight will see some
relief limiting HeatRisk impacts for the region.

The warm up comes to an end early next week as another upper level
trough/low takes aim at NorCal. Expect the marine layer to deepen
once again. One other fall out from the trough will be increasing
northerly winds. Cool and winder conditions will linger through at
least Wednesday.


&&

.AVIATION...
(06Z TAFS)
Issued at 954 PM PDT Wed Jul 16 2025

MVFR-IFR stratus extends from the coast into the Sonoma County
valleys, the East Bay, and the Monterey Bay region. Onshore winds
continue to diminish through the next few hours. Moderate confidence
for stratus impacts at the inland terminals (particularly LVK)
through the night into Thursday morning. Stratus will retreat to the
immediate coast through Thursday morning with breezy onshore flow
resuming in the afternoon.

Vicinity of SFO... The terminal currently sits right on the edge of
an MVFR-IFR stratus bank, with stratus impacts continuing through
the night. The stratus will dissipate Thursday morning with a breezy
west-southwest flow resuming in the afternoon. Stratus returns
Thursday night into Friday morning with low to moderate confidence
on timing.

SFO Bridge Approach... Similar to SFO.

Monterey Bay Terminals... MVFR-IFR stratus persists overnight before
clearing through Thursday morning, potentially into the early
afternoon for MRY. Light winds continue overnight before breezy
onshore flow Thursday afternoon. Stratus is expected to return
Thursday evening with the potential for a late afternoon development
of stratus over MRY.

&&

.MARINE...
(Tonight through next Tuesday)
Issued at 954 PM PDT Wed Jul 16 2025

Light to moderate winds prevail across the majority of the
coastal waters through this weekend. Gusty winds, potentially
hazardous to small craft, develop each afternoon and evening
through the Golden Gate and into the Delta. Moderate seas also
continue through the remainder of the work week, rebuilding to
become rough in the outer waters by Saturday.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 9 AM to 9 PM PDT Friday for SF Bay N
     of Bay Bridge.

     Small Craft Advisory from 3 PM to 9 PM PDT Friday for Pigeon Pt
     to Pt Pinos 0-10 nm.

     Small Craft Advisory from 3 PM Friday to 3 AM PDT Saturday for
     Pt Pinos to Pt Piedras Blancas 0-10 nm.

&&

$$

SHORT TERM...MM
LONG TERM....MM
AVIATION...DialH
MARINE...DialH

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