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000
FXUS66 KMTR 250749
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1249 AM PDT Thu Apr 25 2024

...New SYNOPSIS, SHORT TERM, LONG TERM...

.SYNOPSIS...
Issued at 1201 AM PDT Thu Apr 25 2024

Cool temperatures will continue today. A cold front will bring
a chance for light rain beginning tonight, with strong winds
Friday night. Increasing sunshine will kick off a warming trend
Sat-Tue.

&&

.SHORT TERM...
(Today and tonight)
Issued at 1201 AM PDT Thu Apr 25 2024

A coastal surface trough will continue to weaken and move inland,
allowing a low-amplitude ridge to build. This will cause the
marine layer to compress to about 1,500 ft. Compared to the 4,000
ft deep marine layer observed Wednesday, the low overcast today
will be more limited to the coast and adjacent low valleys. The
standard NW flow will also return as the trough weakens. The cool
temperatures will continue, with highs generally in the 60s. This
ridge pattern will be short lived as a cold front moves through on
Friday.

&&

.LONG TERM...
(Friday through Wednesday)
Issued at 1201 AM PDT Thu Apr 25 2024

Some light rain is possible starting ahead of the cold front
Thursday night, with low PoPs lasting though the day Friday.
22/26 members of the SREF have some precipitation falling at SFO
between Thursday night and Friday, but only 4 of them are above
0.05" of accumulation, and none of those are above 0.1". Similar
results are found throughout the Bay Area, with slightly more
bullish results along the Central Coast. As such, I have
increased the NBM PoPs to at least 15% to ensure a slight chance
of rain is mentioned, but did not increase the QPF from the WPC
guidance, which is near zero. There`s a decent chance some rain
falls late Thursday-Friday, but it will be light.

The bigger impact will be from strong NW winds behind the cold
front. 24 hours ago, it looked like a slam dunk wind advisory
along the coast, but the models have backed off since then. NBM is
on the high side of the guidance, but only shows a slight chance
of exceeding 40 mph gusts along the coast on Friday night. The
timing of the strongest winds has also shifted from Friday
afternoon to overnight Friday. Based on this, and the fact that
other deterministic models are even less aggressive, we are not
hoisting a wind advisory at this time. That being said, there will
be plenty of gusts above 30 mph on Friday and Saturday with some
minor impacts expected.

The weekend will feature clearing skies and slightly warmer
temperatures, although Saturday will still be breezy. The gradual
warm-up will continue through early next week, as the region
returns to seasonal temperatures under mostly clear skies. The
next threat of rain arrives late next week.

&&

.AVIATION...
(06Z TAFS)
Issued at 1122 PM PDT Wed Apr 24 2024

Cloudy and overcast conditions prevail once more, though unlike last
night which saw largely VFR conditions prevailing despite cloud
cover, tonight is likely to see widespread MVFR CIGs as the marine
layer continues to compress as a shortwave ridge builds. This will
lower CIGs to around 1500` for most terminals. At this time, not
expecting CIGs to deteriorate below MVFR, though Monterey Bay
terminals may come close briefly in the mid morning Thursday. Most
terminals clear late in the morning of Thursday, with winds
steadily increasing out of the west to become moderate to strong,
and gusting 20-25+ knots well into the evening hours. KSFO is
likely to see the strongest gusts nearing 30 knots.

Aside from moderate to strong winds and gusty conditions, models are
in good agreement indicating stratus making an aggressive push
inland near 00Z-02Z Friday. Strong onshore winds help advect these
low clouds inland, bringing widespread MVFR conditions once more.
MVFR lasts beyond the TAF period.

Vicinity of SFO...Satellite shows stratus encircling the majority of
the SF Bay at this hour. CIG heights per the KSFO metar are around
1300` at the moment, ushering in MVFR conditions. Expect MVFR CIGs
to last into the late morning before brief lifting to VFR for a few
hours into the afternoon. Despite improvement to VFR conditions, low
to mid level clouds will continue to be present throughout the
duration of the TAF period. Winds will begin to strengthen and gust
25+ knots out of the west by the time of clearing, with winds
continually strengthening into the early afternoon. Stratus and
subsequent MVFR CIGs will return in the early evening, ushered in by
strong westerly winds. MVFR then lasts well beyond the end of the
TAF period with winds slowly decreasing into the late night to
around 10 knots.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...MVFR conditions persist throughout the
night, though KMRY is likely to see IFR develop beyond midnight
Thursday as CIGs continually lower. As it stands, there is between a
60-75% chance of IFR CIG development at the most favored times for
KMRY. Elsewhere, chances only stand at about 50% of achieving IFR
conditions, so have left with prevailing MVFR conditions for now.
This will be something to watch closely through the night however as
confidence on maintaining MVFR conditions for terminals outside
KMRY is marginal. Otherwise, KMRY improves to MVFR as CIGs lift
beyond sunrise. Stratus will continue to shroud area terminals
through the TAF period with no improvement to VFR expected.
Chances of VFR are only in the 30-40% range, therefore have gone
with MVFR prevailing through the entire TAF period. Winds onshore,
moderate, and gusting to around 20 knots beginning in the late
morning and continuing through the late night.

&&

.MARINE...
(Tonight through next Tuesday)
Issued at 1122 PM PDT Wed Apr 24 2024

Gentle to moderate NW winds continue into Friday with occasional
moderate to fresh gusts possible throughout portions of the
coastal waters. Gustier fresh to strong winds with near gale
force and isolated gale force gusts possible heading into Friday
as an upper level trough and surface low pressure system move
inland. Moderate period northwest swell will continue to move
through the waters through Saturday. Light long period southerly
swell continues through end of forecast period.

&&

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

     Small Craft Advisory until 3 PM PDT this afternoon for Pt Arena
     to Pt Reyes 0-10 nm.

     Small Craft Advisory until 3 PM PDT this afternoon for Pigeon Pt
     to Pt Pinos 10-60 NM-Pt Reyes to Pigeon Pt 0-10 nm.

     Small Craft Advisory from 9 AM this morning to 3 AM PDT Friday
     for Pt Pinos to Pt Piedras Blancas 0-10 nm.

     Small Craft Advisory until 9 AM PDT this morning for Pt Arena to
     Pt Reyes 10-60 NM.

&&

$$

SHORT TERM...Flynn
LONG TERM....Flynn
AVIATION...AC
MARINE...Kennedy

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