316
FXUS66 KMTR 052356
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
456 PM PDT Tue Aug 5 2025

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 103 PM PDT Tue Aug 5 2025

 - Gradual warming trend begins today and lasts into the weekend.

 - Patches of Moderate HeatRisk Friday through Sunday in the
   interior East and South Bays.

 - Elevated fire weather concerns given the warming and drying
   trend coupled with daily afternoon/evening breezes.

&&

.SHORT TERM...
Issued at 125 PM PDT Tue Aug 5 2025
(This evening through Wednesday)

Another pleasant day weather wise around the Bay Area and Central
Coast. Temperatures have been a little slower to warm up today
given a slightly better marine layer/ocean influence earlier this
morning. Despite the ample sunshine and expected warm up highs
today will still fall short of seasonal averages for early
August.

For this evening and tonight: Patchy stratus off the San Mateo
coast will linger with additional stratus re-developing along the
coast and locally into SF Bay and Monterey Bay. Another night of
active thermal belts with mild/dry conditions over the higher
terrain.

Wednesday...will feature a more noticeable warm up across the
region. The evolving longwave pattern will be a similar pattern
that we`ve experienced a few times this cooler than normal summer.
Upper level high pressure over the Desert SW and upper level high
pressure over EPac will squeeze an upper level trough over the
West Coast. The "squeeze" will be seen as rising 500mb heights
and warming 850mb temps. While there is a warm up expected,
onshore flow remains so coastal/bay regions will be more muted
with more heat confined to the interior. In other words, a large
temp spread from the coast to the interior (20-30 degs). Highs on
Wednesday will be 60s to near 80 at the coast and 80s to 90s
inland. Far interior Central Coast and East Bay have a 40-50% chc
of exceeding 100 degrees. Those far interior locations nudge
upward to Moderate HeatRisk.

&&

.LONG TERM...
Issued at 145 PM PDT Tue Aug 5 2025
(Wednesday night through next Monday)

Thursday will be an interesting day as the warming trend gets a
brief pause with moderating temperatures. The longwave pattern has
a similar feel, but the squeezed trough deepens a little as the
parent upper low rolls in the Great Basin. That feature quickly
moves eastward by Friday allowing the warm up to resume. In fact,
there are now a few interior pockets hitting 100 degrees on
Friday. The forecast trend for the weekend has been warmer as
well. Simply put, Friday through Monday will feature minor day to
day fluctuations for temperatures.

Two things that we`re monitoring closely: fire weather and TS
Henriette. Will continue to advertise elevated fire weather
concerns through early next week with warm and dry conditions
coupled with daily onshore pushes. Additionally, higher terrain
will not see much in the way of relief. TS Henriette is currently
1000 nm SW of Baja. Water Vapor does show some upper level
moisture being advected northward. However, model guidance doesn`t
bring any of that moisture to CA around the Desert SW high.
Obviously, if we pull in some tropical moisture into CA that
would change things, but for now it looks dry.

&&

.AVIATION...
(00Z TAFS)
Issued at 438 PM PDT Tue Aug 5 2025

VFR will continue through the evening hours until early Tuesday
morning for all stations. There is potential for MVFR/IFR ceilings
in the pre-dawn hours at KHAF and KOAK, but confidence is low of
that occuring. Breezy winds develop late in the TAF period
tomorrow,especially in the Bay Area, but not as strong as the
previous couple of days.

Vicinity of SFO...VFR will prevail for a majority of the TAF
period with low chance of MVFR/IFR ceilings at KHAF and KOAK.
Breezy onshore winds will develop in the late afternoon and
continue into Wednesday evening.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR will continue through the evening
hours into the predawn hours of Wednesday morning, when there is a
chance for MVFR/IFR ceilings to develop and likely erode by mid-
morning, with VFR for the remainder of the TAF period on
Wednesday.

&&

.MARINE...
(Tonight through next Sunday)
Issued at 438 PM PDT Tue Aug 5 2025

Northwest winds increase by Wednesday with widespread fresh to
occasional near gale force gusts possible. Winds will diminish
Friday and into the weekend with a gentle to moderate
northwesterly breeze prevailing. Moderate seas continue through
the forecast period. Wave heights briefly build to around 10 feet
across the northern outer waters late this week before diminishing
throughout the weekend.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 9 PM PDT this evening for Mry Bay-
     Pigeon Pt to Pt Pinos 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.

     Small Craft Advisory until 3 AM PDT Thursday for Pigeon Pt to Pt
     Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm-Pt Arena to Pt
     Reyes 10-60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm.

     Small Craft Advisory from 3 PM Wednesday to 3 AM PDT Thursday
     for Pt Reyes to Pigeon Pt 0-10 nm.

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

&&

$$

SHORT TERM...MM
LONG TERM....MM
AVIATION...JM
MARINE...RGass

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