-- Discussion containing changed information from previous version are highlighted. --
644
FXUS66 KMTR 080412 AAC
AFDMTR

Area Forecast Discussion...UPDATED
National Weather Service San Francisco CA
912 PM PDT Fri Jun 7 2024

...New UPDATE...

.SYNOPSIS...
Issued at 336 AM PDT Fri Jun 7 2024

Cooling continues through the weekend, with temperatures largely
near seasonal averages. Warming returns early next week as ridging
redevelops, though not expecting temperatures to reach as high as
they did the last few days.

&&

.UPDATE...
-- Changed Discussion --
Issued at 853 PM PDT Fri Jun 7 2024

The short term forecast is in good shape with just some minor
tweaks to overnight wind grids for some of the East Bay
Hills/Mountains, as well as across coastal waters (including the
northern part of the San Francisco/San Pablo Bay areas).

Flow this evening along the shoreline remained quite brisk,
especially along the Marin Headlands up toward Bodega Bay. In
fact, the Bodega Bay Profiler indicates around 35 knots of flow
around 1km. Whether or not this momentum mixes down to the surface
is a little uncertain, however, some of the short-term guidance
(e.g., HRRR) suggests this is a possibility. Winds across some of
the coastal waters---from Bodega Bay down through the Golden Gate
Gap were adjusted upward to the 75th NBM percentile. Winds appear
that they`ll channel through the Golden Gate Gap and accelerate
through portions of the SF and San Pablo Bays, as well as the west
Delta. East Bay Hills and Mountains may also be recipients of
this accelerated flow. The 75th percentile NBM numbers translate
to 20 to 30 mph wind gusts later tonight into the pre-dawn hours
on Saturday morning. The impact will be rough boating conditions
for small craft as well as an increased potential for any loose
outdoor articles (trash cans, lawn furniture) to be blown about in
the wind.

The rest of the forecast remains in good shape and updated
products have been transmitted.
-- End Changed Discussion --

&&

.SHORT TERM...
(This evening through Saturday)
Issued at 218 PM PDT Fri Jun 7 2024

Low stratus clouds continue to linger along the coastline with some
sunshine occasionally breaking through this afternoon. Clear skies
farther inland have allowed temperatures to climb into the 70s and
80s, with some higher elevations to the east and south in the 90s
with breezy west/southwest surface winds. An upper level ridge axis
will shift east across our area for the remainder of today and
tonight while an upper trough deepens over the open water to our
west. The upper trough will produce increasing mid/high clouds
tomorrow afternoon helping to cool temperatures a few degrees
inland, while low stratus clouds persist keeping temperatures along
the coast in the 60s. The slow moving upper trough will result in
similar conditions on Sunday.

&&

.LONG TERM...
(Saturday night through next Thursday)
Issued at 218 PM PDT Fri Jun 7 2024

The aforementioned slow moving upper trough eventually shifts east
by early Monday morning, while a cutoff low splits off from the
southern portion of the trough over the southeast Pacific. There`s
some uncertainty in the synoptic longwave pattern across our area,
depending on how the cutoff low evolves over the weekend. The
warming trend for the middle of next week and beyond remains in the
forecast but the max temperatures have trended slightly lower. The
warmer temperatures peak on Wednesday, with a gradual cooling trend
for late in the week as the cutoff low begins to move onshore across
SOCAL.

&&

.AVIATION...
(00Z TAFS)
Issued at 456 PM PDT Fri Jun 7 2024

Currently VFR at all stations except SNS. VFR will transition to
MVFR-LIFR heading into the late evening as a deeper marine layer
allows for stratus to intrude farther inland. Confidence is moderate
to high that stratus will reach STS, APC, OAK, SFO, MRY, and SNS.
There is more uncertainty on stratus reaching SJC and LVK with
models lacking a consensus on inland stratus extent. Forecast RH
values remain fairly high at both airports so leaning towards
stratus reaching them but, particularly for LVK, stratus may only be
present for a few hours mid-morning. Some potential for patchy fog
to develop across the North Bay and Central Coast which may cause
visibility and ceiling heights to dip - will continue to monitor and
revise TAFs as needed.

Vicinity of SFO...VFR transitioning to MVFR overnight. Stratus is
expected to return this evening around 08Z with a few models
indicating an earlier return between 06-07Z. Moderate confidence
that ceiling heights will stay MVFR. Main change to SFO TAF was
pushing up stratus departure time tomorrow morning to 19Z from 21Z.
RH values decrease more significantly and winds pick up beginning at
18Z which should contribute to stratus dissipation. A few models
lean on stratus dissipation closer to 18Z but confidence is low at
this time. Moderate onshore flow continues through the day before
weakening slightly overnight. Gusty conditions look to return
tomorrow afternoon with gusts up to 25 knots expected.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...MVFR transitioning to IFR-LIFR at SNS and
VFR transitioning to MVFR-LIFR at MRY. Stratus return timing for MRY
is a bit tricky tonight. Visible satellite shows (as of 00Z) stratus
receding slightly along the Monterey Bay coastline which may impact
the 01Z ceiling arrival time at MRY. For now, continuing the 01Z
arrival time at MRY as stratus coverage should grow as the sun goes
down but it may need to be pushed back closer to 02Z. Ceiling
heights at MRY and SNS will decrease to LIFR overnight with some
potential for fog to develop early to mid-morning (12Z - 16Z time
frame) which may cause decreased visibility. Moderate, gusty onshore
winds continue through the evening before weakening overnight.
Stronger winds return by late tomorrow morning with gusts up to 20
knots possible.

&&

.MARINE...
(Tonight through next Wednesday)
Issued at 456 PM PDT Fri Jun 7 2024

Overcast conditions continue over the majority of the coastline
with  low level stratus coverage to become more widespread
overnight.  Potential for patchy fog, patchy haze, and light
drizzle returns  tonight and continues through tomorrow morning
which may result in  temporarily reduced visibilities. Northerly
to northwesterly flow  continues over the coastal waters with
widespread fresh to strong  gusts conditions spreading north to
south over the waters beginning  Saturday. Significant wave
heights gradually build over the outer  coastal waters moving into
the weekend and inner coastal waters by  the late weekend.
Hazardous conditions for small crafts continue  over the outer
coastal waters with conditions over the inner coastal  waters
becoming hazardous by late weekend.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CA...None.
PZ...Small Craft Advisory until 3 AM PDT Sunday for SF Bay N of Bay
     Bridge.

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

     Small Craft Advisory until 3 PM PDT Sunday for Pt Arena to Pt
     Reyes 10-60 NM-Pt Reyes to Pigeon Pt 0-10 nm.

     Small Craft Advisory from 3 PM Saturday to 3 PM PDT Sunday for
     Pigeon Pt to Pt Pinos 10-60 NM.
-- End Changed Discussion --

&&

$$

UPDATE...Bain
SHORT TERM...JM
LONG TERM....JM
AVIATION...Kennedy
MARINE...Kennedy

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