-- Discussion containing changed information from previous version are highlighted. --
679
FXUS66 KMTR 131141
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
441 AM PDT Thu Jun 13 2024

...New AVIATION...

.SYNOPSIS...
Issued at 247 AM PDT Thu Jun 13 2024

Quiet through the rest of the week with slight warm up on Friday
across the interior. Near normal temperatures by the weekend.
Increasing confidence for high wind potential and increased fire
danger Sunday into early next week.

&&

.SHORT TERM...
(Today through Friday)
Issued at 247 AM PDT Thu Jun 13 2024

Temperatures this afternoon will be similar to those yesterday as
zonal flow conditions north of the region while an upper level low
remains parked off of southern California. Temperatures this
afternoon will range from the upper 50`s to 60`s near the coast and
bayshore, 70`s to near 80 degrees just inland and into the East Bay,
Santa Clara Valley, and southern Salinas Valley. The regions
farthest interior will reach into the upper 80`s to low 90`s.

Tonight, expecting less widespread stratus to penetrate inland as
the marine layer begins to compress. Overnight low temperatures are
forecast to be in the upper 40`s across the North Bay and San
Francisco Peninsula with low/mid 50`s elsewhere.

Friday will be slightly warmer in response to increased sunshine,
northerly winds, and weak ridging aloft. Coastal/bayshore areas will
remain cool but the interior will see more upper 80`s to low 90`s.

&&

.LONG TERM...
(Friday night through Wednesday)
Issued at 247 AM PDT Thu Jun 13 2024

Heading into the weekend will be relatively quiet as temps cool a
bit again down to around seasonal normals. The real story will be
later in the weekend and into early next week. A deep upper low
currently up in the Gulf of Alaska becomes dislodged and moves
into the Pacific Northwest, kicking off another deep disturbance
sliding into the West Coast/Great Basin. Well advertised by
ensemble cluster analysis, there is high confidence in this
pattern change taking place Sunday into Tuesday. Placement of the
upper level trough axis is key when determining where the
strongest winds will be and their direction. There is higher
confidence that the strongest winds will remain over the waters
and near coastal areas, including more inland coastal gaps such as
the Petaluma Gap, San Bruno Gap, and other NW-SE oriented valleys.
While we aren`t expecting any widespread offshore winds as of this
forecast, the positioning of the trough will ultimately be the
deciding factor, so stay tuned to future updates as confidence
gradually increases. With grasses and fine fuels drying out
rapidly, it looks like the Sunday-Monday timeframe is one to watch
when it comes to elevated fire danger, particularly in the North
Bay where fine fuels are drier than elsewhere around the Bay Area
and Central Coast. For now, moisture recovery looks decent going
into the weekend as winds should remain onshore, but we are
keeping a close eye on the positioning of the trough and will
update messaging accordingly.

&&

.AVIATION...
-- Changed Discussion --
(12Z TAFS)
Issued at 441 AM PDT Thu Jun 13 2024

Stratus this morning continues to bring a mix of MVFR and IFR
conditions across the region. Beyond sunrise, clearing to VFR is
expected for most terminals with the exception of Monterey Bay as
stratus begins to erode with daytime heating. Winds generally W/SW
this afternoon and breezy, occasionally gusting near 20 knots for
coastal terminals. Stratus returns into the late night for most
terminals bringing MVFR CIGs. With an approaching trough from the
NW, thoughts are that CIGs will lift and maintain predominantly
MVFR through the remainder of the TAF period.

Vicinity of SFO...VFR through the late night tonight. Winds increase
out of the W/SW this afternoon to become breezy around 12 knots.
Some disagreement between models as to whether winds will lean more
westerly or southwesterly, though with a cutoff low to the south
beginning to lift out, current thoughts are that winds will start
out SW in the morning, but turn to become more W into the evening.
Stratus then appears early Friday morning, bringing MVFR CIGs.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...No clearing expected today at KMRY, though
CIGs will lift to become MVFR towards the late morning. Stratus will
be continually fed inland by breezy to moderate SW winds this
afternoon. Only brief clearing to VFR is expected at KSNS, though
confidence in clearing is low. MVFR CIGs from stratus expected at
all terminals from the early evening and through the remainder of
the TAF period, though there is some question as to whether CIGs may
lower to become IFR in the night. Thoughts are that CIGs will likely
stick close to MVFR altitudes, but may flirt the border with IFR
towards the late night.
-- End Changed Discussion --

&&

.MARINE...
(Today through Tuesday)
Issued at 247 AM PDT Thu Jun 13 2024

Fresh northwesterly winds continue over the northern waters
through the end of the week. Towards the weekend, northwesterly
winds strengthen to become strong and gusting to gale-force over
much of the waters. Significant wave heights up to around 12 to
15 feet in the outer waters continue into the weekend.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CA...None.
PZ...Small Craft Advisory from 3 PM this afternoon to 9 AM PDT Friday
     for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-
     10 nm.

     Small Craft Advisory until 9 AM PDT Friday for Pt Arena to Pt
     Reyes 10-60 NM.
-- End Changed Discussion --

&&

$$

SHORT TERM...RGass
LONG TERM....Behringer
AVIATION...AC
MARINE...AC

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