241
FXUS66 KMTR 171158
AFDMTR

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

...New AVIATION, MARINE...

.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...
(12Z TAFS)
Issued at 458 AM PDT Thu Jul 17 2025

Widespread MVFR/IFR CIGs are affecting the region with light winds.
Sites begin to clear in the mid to late morning with most TAF sites
going VFR in the late morning and early afternoon. The exception
will be HAF, which sees clearing in the mid afternoon. Winds look to
stay light to moderate through the morning and increase into late
the late morning and afternoon. Expect these winds to reduce into
evening as MVFR/IFR CIGs begin to move inland from the coast and
filling over most areas by the late night.

Vicinity of SFO...MVFR CIGs will affect the terminal through the
late morning before clearing. Winds stay light through the early
afternoon before breezy west winds return. These winds reduce into
the night as MVFR CIGs fill around the SF BAY and SFO. These CIGs
look to last through late Friday morning before eroding.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...IFR/MVFR CIGs with light winds last into
the late morning. Winds become moderate into the late morning and
early afternoon as CIGs erode over the terminals, but expect cloud
cover to linger over the Monterey Bay and offer scattered cloud
cover through the afternoon for MRY. Winds weaken again into
Thursday evening with IFR CIGs moving over the terminals.&&

.MARINE...
(Today through Tuesday)
Issued at 458 AM PDT Thu Jul 17 2025

Expect light to moderate winds 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 as well as the favored coastal jets
along Pigeon Point and Big Sur. 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...Murdock
MARINE...Murdock

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