-- Discussion containing changed information from previous version are highlighted. --
453
FXUS66 KMTR 260306
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
806 PM PDT Sat May 25 2024

...New UPDATE...

.SYNOPSIS...
Issued at 1259 AM PDT Sat May 25 2024

Cool with abundant overnight stratus through the weekend. Warming
and drying trend set for next week with temperatures around
seasonal normal.

&&

.UPDATE...
-- Changed Discussion --
Issued at 805 PM PDT Sat May 25 2024

Temperatures this afternoon where anywhere between 4-11 degrees
below seasonal averages. That said, mostly sunny sky conditions were
seen by late afternoon/early evening. Tonight, expecting low
temperatures to fall into the low-to-mid 40`s to near 50 degrees
across the region. The ongoing forecast remains on track with no
updates needed at this time.
-- End Changed Discussion --

&&

.SHORT TERM...
Issued at 118 PM PDT Sat May 25 2024
(This evening through Sunday)

Another afternoon of lingering pesky stratus from the morning.
The lingering clouds are slowly thinning per satellite and have a
strato-cu look. Needless to say the clouds are impacting
temperatures across the interior with a few spot running behind
predicted max temps. We`ll leave forecast as is since there`s
still some daytime heating left and some inland sunshine is still
predicted. One thing that is similar to yesterday are the
stronger onshore winds. While not as strong as 24 hours ago,
still seeing some gusts up to 35 mph through the inland
gaps/passes.

Finishing out the weekend: The upper level trough that helped
support the deep/cool/moist marine layer will exit eastward.
Semi-zonal flow with building 500 mb heights and warming 850 mb
temps will build over the region. As a result, a more compressed
marine layer will develop tonight. Still cannot rule out patchy
fog or drizzle tonight, but it should be less than Saturday
morning. Temperatures on Sunday will warm on avg 3-8 degrees away
from the coast. Highs will be in the upper 50s to 60s coast and
70s to mid 80s. Onshore flow continues to ease, but gusty winds
through gaps/passes will continue.

&&

.LONG TERM...
Issued at 140 PM PDT Sat May 25 2024 (Sunday night through next
Friday)

The warming trend from Sunday will continue through much of next
week as high pressure nudging in from the S battles an upper
trough approaching from the N. As for sensible weather, pretty
quiet with night and morning clouds with inland daytime sunshine.
Should be noted the warming trend will pause briefly mid-week
before peaking next Friday with far interior locations reaching 90
degrees.

&&

.AVIATION...
-- Changed Discussion --
(00Z TAFS)
Issued at 605 PM PDT Sat May 25 2024

Diurnal surface warming and greater vertical mixing due to a
weakened lower level temperature inversion(s) have mostly mixed
out the low clouds today. Currently much of the forecast area is
VFR with exception of a few patches of low clouds and haze /MVFR/
along the coast.

The air mass is essentially unchanged at the moment, however
there are hints in the model output that another push of surface
to near surface cooler air will arrive from the northwest and
over the coastal waters overnight and Sunday morning, assisting
with redevelopment of low clouds /MVFR-IFR/; sea surface temps are
49F-54F, surface dewpoint temps are roughly the same and outgoing
radiative cooling tonight favor low cloud redevelopment. Warming
in the lower levels of the atmosphere will be slow to start tonight,
but is forecast to increase/consolidate through Sunday and Sunday
night resulting in the restrengthening of a lower level temperature
inversion (cap for stratus and/or fog development). The afternoon
Oakland upper air sounding showed the lowest inversion based near
2600 feet AGL, and two subsidence inversions were based at 4500 feet
AGL and at 8000 feet AGL.

Vicinity of SFO...BKN cloud cover has reduced to SCT cloud cover
with sufficient afternoon surface warming and mixing. Post sunset
however and incoming cooler air advection will combine to bring
back low clouds /MVFR/ mid-late evening; a moderate to high
confidence forecast. MVFR tonight and Sunday morning. Decided to
extend MVFR ceiling forecast to 21z Sunday before clearing takes
place based on the NAM humidity forecasts, combining with
aforementioned cooling to saturation. West wind 15 to 25 knots,
easing to near 10 knots tonight and Sunday morning, then westerly
15 to 20 knots Sunday afternoon and evening.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Near high confidence VFR continues to
mid evening then MVFR-IFR developing due to low clouds. MVFR-IFR
tonight and Sunday morning mixing out to VFR by late morning. West
to northwest winds 10 to 20 knots decreasing to 5 to 10 knots by
late evening, west to northwest winds resuming to 10 to 20 knots
Sunday afternoon and early evening.
-- End Changed Discussion --

&&

.MARINE...
(Tonight through next Thursday)
Issued at 448 PM PDT Sat May 25 2024

Fresh northwest breeze over the outer waters persists through the
weekend creating hazardous conditions for small crafts. Fresh to
strong northwest and onshore winds across the coastal waters and
bays during the afternoons by early to mid next week. Wave heights
beginning to increase mid-work week up to 11-13 feet. Otherwise
mostly quiet marine conditions through the forecast period.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 9 PM PDT this evening for Mry Bay.

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

     Small Craft Advisory from 3 PM to 9 PM PDT Sunday for Pt Arena
     to Pt Reyes 0-10 nm.

     Small Craft Advisory until 3 AM PDT Monday for Pigeon Pt to Pt
     Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM.

&&

$$

UPDATE...RGass
SHORT TERM...MM
LONG TERM....MM
AVIATION...Canepa
MARINE...SO

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