Atherton, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

618
FXUS66 KMTR 070427
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
927 PM PDT Fri Jun 6 2025

...New AVIATION...

.SYNOPSIS...
Issued at 103 PM PDT Fri Jun 6 2025

Mostly quiet conditions prevail through the forecast period with
warm temperatures inland and cool, seasonable temps along the
coast. Slight cooling trend by the middle of next week as a deeper
trough pattern develops off the West Coast.

&&

.UPDATE...
Issued at 858 PM PDT Fri Jun 6 2025

Not a bad way to finish the workweek weather wise, seasonably mild
conditions around the Bay Area and Central Coast.  Sunny skies
blanketed the inland areas with highs reaching the 70s to mid 90s.
Quite a different story by the ocean as low clouds hugged the coast
keeping temps chilly and in the upper 50s to 60s.  It`s June so this
shouldn`t be that much of a surprise.  Daytime heating combined with
a little bit of upper level moisture led to a few fair weather cu
popping over the Gabilan Range this afternoon, but they have since
faded now that the sun is setting.  We even had a little Sierra
tstorm blow off drift westward over portions of the Bay Area as
well.  One other weather item of note were the winds.  Persistent
onshore flow led to stronger onshore winds this afternoon with the
strongest winds over the inland valleys, interior gaps, and passes.
Max observed gusts were 25-35 mph with an isolated gust to 40 mph.

For tonight - more of the same. The marine layer that stayed over
the coastal waters this afternoon will move inland again. Saturday
will start out cloud for a good chunk of the inland valleys.

No forecast update needed...

MM

&&

.SHORT TERM...
(This evening through Saturday)
Issued at 103 PM PDT Fri Jun 6 2025

Stratus quo, deja vu, groundhog day, whatever you want to call
it. Inland areas heating up to comfortable and seasonable
temperatures today while the coastline is once again leaving folks
in a paralyzing state of "should I bring a jacket". Then they
don`t because it feels nice at first and end up regretting it 30
minutes later. This trend generally continues into the weekend
with inland locations heating up by a few more degrees while
coastal locations remain in this cool but nice state with near
normal temperatures. A few coastal locations will see temps a bit
more tolerable for short sleeves and shorts such as Santa Cruz,
Big Sur, and Monterey (for like a couple of hours). Are
convertible pants still a thing? I digress.

&&

.LONG TERM...
(Saturday night through next Thursday)
Issued at 103 PM PDT Fri Jun 6 2025

Really not much change into the end of the weekend with the upper
level ridge mostly staying put, and nothing to drive the weak
closed low away. Therefore, the pattern is slow to revert. By the
middle of the week, guidance depicts a deeper open wave trough
that would kick off a cooling trend into late next week. Ensemble
guidance has been greatly confident in advertising this whole
pattern evolution over the next several days. All-in-all, most
people aren`t going to notice much day-to-day difference before
the middle of next week with the exception of the inland areas
recognizing that their car thermometer says 82 instead of 80.

&&

.AVIATION...
(06Z TAFS)
Issued at 927 PM PDT Fri Jun 6 2025

Coastal stratus /MVFR possibly IFR/ continues to fill back in
along the immediate coastline per surface observations and
satellite imagery. A weak low pressure area straddles the CA
coastal waters and offshore waters. Post sunset surface pressure
gradients and winds are already easing in response to nocturnal
cooling and subsequently a decrease in land vs sea surface temps,
leaving the onshore SFO-SAC pressure gradient/wind to predominate
and usher in stratus and/or fog tonight and Saturday morning. The
marine layer depth varies from several hundred feet to 1700 feet.

The aforementioned low pressure area will slowly drift southwest
tonight and Saturday, which should allow a surface ridge of high
pressure to build in over the coastal waters mainly resulting in
strengthening SFO-SAC pressure gradient/wind this time tomorrow;
just don`t know with certainty, will have to closely monitor.

Vicinity of SFO...So far the stratus is staying on the ocean side
of the SF Peninsula keeping VFR going at SFO this evening.
However, stratus is forecast to arrive at SFO tonight and Saturday
morning. RAP model is pessimistic with low ceiling tonight and
Saturday morning at KSFO. Current forecast indicates VFR returning
by late morning Saturday (RAP model is near 100% humidity near
surface thru 18z-19z Saturday). West to northwest wind gusting to
25 knots this evening, near 10 knots overnight and Saturday
morning, west to northwest wind increasing to 25 knots Saturday
afternoon and early evening.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Onshore winds and nocturnal cooling are
resulting in stratus /MVFR-IFR/ with IFR tonight and Saturday
morning. Stratus and any lingering patchy fog will mix out late
Saturday morning. Winds becoming mainly onshore during the evening
and overnight 5 to 10 knots. Onshore winds Saturday afternoon and
early evening 10 to 15 knots. Stratus moving back inland Saturday
night and Sunday morning.

&&

.MARINE...
(Tonight through next Thursday)
Issued at 858 PM PDT Fri Jun 6 2025

A weak low pressure area will drift to the southwest over the
offshore waters tonight and Saturday. Breezes will become more
westerly on Saturday. Diurnal effects will bring a fresh to strong
SW breeze to the San Francisco Bay over the next couple
afternoons. A long period southwesterly swell arrives early next
week. Winds  and seas will rebuild more substantially mid to late
next week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 3 PM to 9 PM PDT Saturday for SF Bay N
     of Bay Bridge.

&&

$$

SHORT TERM...Behringer
LONG TERM....Behringer
AVIATION...Canepa
MARINE...Canepa

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