329
FXUS66 KMTR 180414
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
914 PM PDT Fri May 17 2024

...New UPDATE, MARINE...

.SYNOPSIS...
Issued at 108 PM PDT Fri May 17 2024

Quiet weather persists. Widespread stratus coverage dissipating by
mid-to-late morning with breezy, clear conditions developing by the
afternoon. Heading into the weekend, stratus coverage will be
diminished with stratus primarily confined to coastal regions and
down into the Salinas Valley.

&&

.UPDATE...
Issued at 914 PM PDT Fri May 17 2024

If you`ve been following the weather these past few days, you know
what`s coming: Satellite imagery is showing marine layer stratus
building from the coast and flowing into the interior, expected to
expand in coverage through the night. The clouds are expected to
retreat to the coast in the morning, with onshore flow developing
into the afternoon and clear skies expected through the day across
the interior. No changes to the forecast at this time.

DialH

&&

.SHORT TERM...
(This evening through Saturday)
Issued at 108 PM PDT Fri May 17 2024

Low clouds continue to erode across most inland areas as of early
afternoon, but are still hanging on around the Monterey Bay region
and adjacent valleys, Santa Cruz Mountains, and coastal areas of the
North Bay. Tonight, expecting less inland penetration of stratus
across the North Bay and the greater San Francisco Bay Area.
However, stratus will spread back inland and down into the Salinas
Valley (and adjacent valleys). Where stratus does develop, drizzle
will remain possible again tonight into Saturday morning.

Morning cloud cover will retreat back to the coast by mid-to-late
morning or early afternoon. Saturday will be seasonably cool with
temperatures near the coast in the upper 50`s to mid 60`s and mid
60`s to upper 70`s inland across the far interior.

&&

.LONG TERM...
(Saturday night through next Friday)
Issued at 537 PM PDT Fri May 17 2024

An upper level trough develops over the West Coast later in the
weekend, the first in a series of upper level troughs expected to
impact the western United States through the next week. The
troughing pattern will cool 850 mb temperatures to around the mid
to upper 50s. Coincidentally, sea surface temperatures as
currently observed are also around this range, and an old rule of
thumb is that stratus decks don`t typically develop whenever the
850 mb and sea surface temperatures are close to each other. The
end result of all of this: a potential for more enhanced mixing
out of the marine layer next week, with a consequent warmup for
the inland regions in the early part of the work week. Temperature
forecasts for next week are low confidence at this time. The
current expectation is for highs to range from the mid 70s to the
low 80s in the inland valleys, with coastal regions remaining
cool near the upper 50s to lower 60s.

CPC products show a lean towards temperatures below seasonal
averages, and precipitation above seasonal averages, through the
end of May.

&&

.AVIATION...
(00Z TAFS)
Issued at 505 PM PDT Fri May 17 2024

A discontinuous marine layer continues to hug the coast this
evening with MVFR cigs impacting MRY and SNS. Once the sun sets do
expect the marine layer to move inland, but inland impacts are
lower confidence especially inside SF Bay and East Bay. Any
Saturday morning cigs will erode back to the coast with VFR
expected at all terminal Saturday afternoon. Additionally, there
is a 20-30% of fog impacting MRY and SNS Saturday morning.

Vicinity of SFO...Breezy NW winds will persist through the
evening rush. Cigs will linger in the gap this evening, but not
expecting cigs at SFO.

SFO Bridge Approach...Some cigs around 1500 feet have a chc of
impacting the approach during the Saturday AM rush. Conf is
50-60%.

Monterey Bay Terminals...Despite a SW wind at MRY cigs remain.
TAFS were update to keep cigs this evening and for the rest of
the night. Less than 15% chc of a brief period of SCT cigs at
MRY/SNS this evening. Cigs have a better chance of clearing late
Saturday AM.

&&

.MARINE...
(Tonight through next Thursday)
Issued at 914 PM PDT Fri May 17 2024

Strong high pressure off the Pacific Northwest coast and low
pressure over southern Nevada will maintain moderate to locally
strong northerly winds. Winds will gradually increase over the
weekend. The strongest winds will be strong north of Point Reyes,
especially the outer waters with gale force gusts. Stronger winds
will lead to hazardous conditions and steeper wind waves.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 3 PM Saturday to 9 AM PDT Sunday for
     Pt Arena to Pt Reyes 0-10 nm.

     Small Craft Advisory until 3 PM PDT Saturday for Pt Arena to Pt
     Reyes 10-60 NM.

     Gale Warning from 3 PM Saturday to 9 AM PDT Sunday for Pt Arena
     to Pt Reyes 10-60 NM.

     Small Craft Advisory from 9 PM Saturday to 9 AM PDT Sunday for
     Pigeon Pt to Pt Pinos 10-60 NM.

&&

$$

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

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