Small Craft Advisory 77, NWS San Francisco Bay Area, CA

Area Forecast Discussion
National Weather Service San Francisco Bay Area
247 PM PDT Mon Apr 11 2022

.SYNOPSIS...Breezy and gusty onshore winds will persist through
this evening before diminishing overnight in wake of a frontal
passage. Temperatures will also turn colder overnight and remain
below seasonal averages through midweek. Unsettled weather will
then continue through late week with the potential for additional
rainfall as early as late Wednesday.

&&

.DISCUSSION...as of 02:44 PM PDT Monday...Clearing sky conditions
and breezy northwest winds are developing in wake of an exiting
frontal boundary that brought widespread rainfall to the region.
Rainfall amounts range from a trace (in the rain shadowed valleys)
to around 0.10" in most urban areas. Meanwhile, southwest facing
locations along the coast/coastal ranges picked up between 0.25"
to 0.50" with isolated amounts up to around 1.00" along the Marin
Peninsula just south of Mount Tamalpais. As of 2 PM PDT, the front
is about to clear the Monterey and San Benito counties with
rainfall over the region coming to an end. As mentioned above,
breezy and gusty winds prevail just about across the entire region
with gusts of 40 to 50 mph reported along the coast and in the
coastal ridges/peaks. These winds are forecast to remain gusty
through the afternoon before diminishing slightly this evening and
moreso overnight.

As winds diminish overnight, clear sky conditions and cold air
advection aloft will allow for temperatures to drop into the 30s and
40s region-wide. This may result in patchy frost across the
sheltered valley locations by early Tuesday morning. Meanwhile,
daytime temperatures will struggle to warm out of the 50s on Tuesday
and lower 60s on Wednesday. Dry weather is also likely to prevail
tonight through at least midday Wednesday.

Additional rainfall will then be possible as early as Wednesday
night across northern California and as far south as the North Bay
ahead of another frontal system. As the weakening boundary drops
southward, light rain may be possible as far south as the Santa Cruz
Mountains early Thursday. Forecast models continue to differ on
timing and exact location of each weather system that may bring
rainfall to the region. Thus, confidence in the details at this
point remains difficult to nail down. However, forecast ensembles
are in good agreement with respect to broad troughing over the
region being the main driver of our weather pattern through late
week and potentially even into the upcoming weekend. As such, look
for temperatures (both daytime and overnight) to remain below
seasonal averages along with chances for precipitation at times
through late week. Again, the greater probabilities of precipitation
and rainfall amounts will be across the North Bay and taper lower as
you move southward across the region. Stay tuned...

&&

.AVIATION...as of 10:38 AM PDT Monday...For the 18Z TAFs. The
front is moving southeastward through the region, with the
boundary passing literally just south of KSFO at the time this
discussion was published. Behind the front to the north is
clearing skies with SCT could bases around 3000 feet, with
occasional 1500 feet. Ahead of the front to the south continues
light rain and BKN/OVC clouds at or just below 1000 feet. The
front should pass south of the Monterey Bay between 20Z and 21Z.
After the front passing, a spare random shower might pop-up
briefly at or near terminals, but no major impacts expected. Rain
accumulation have only been a few hundredths, but enough for wet
runaways. With cold overnight temps and the added moisture, there
is a chance for light patchy shallow fog Tuesday morning, but
confidence was in mostly VFR through the TAF.

The bigger impact to area terminals will be the strong and gusty
northwest winds in the post frontal environment. Winds have
already start gusting between 25 to 30 kts. There is a chance for
up to 40 kt gusts at coastal terminals Monday afternoon. These
winds will likely remain through much of Monday and evening, yet
stay breezy overnight. LLWS is a possible if the surface winds cut
off, but LLWS has only been added to North bay terminals where
confidence was strongest. Tuesday will be windy and VFR.

Vicinity of KSFO...As the front exists, improving conditions are
expected by 19Z, though lingering light showers may crop up at or
around the terminal into the early afternoon. Current IFR cigs
should break up to VFR conditions by 19Z. Gusty onshore winds
return Monday afternoon, persisting through the evening. Winds may
have a lull early Tuesday morning, but increase Tuesday afternoon
with VFR conditions.

KSFO Bridge Approach...Similar to KSFO.

Monterey Bay...MVFR with the chance for IFR conditions for both
cigs and vis as the rain moves down the coast. VFR conditions will
return after 21Z when the front moves southward. Slight chance for
lingering showers in the post-frontal environment, but conditions
should dry out. Winds increase and be southwesterly before the
front, then turn to the northwest after the front Monday
afternoon with gusts between 25 to 30 kts possible. With cool
overnight temperatures and an influx of moisture, there is a
chance for low clouds to build up along the mountain ranges, but
confidence is too low to add to the TAF at this time. Tuesday will
be VFR and breezy.

&&

.MARINE...as of 02:44 PM PDT Monday...Skies have cleared as the
cold front moves southward past Point Sur. Northwest winds behind
the front have increased with gale force gusts over most of the
waters. Winds will remain gusty through Monday evening, not
diminishing until Tuesday afternoon. The sea state will remain a
wind driven swell between 8 to 10 seconds through mid week. A
brief lull in the winds is forecast on Wednesday before the next
system drops southward for another chance of rain over the waters.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tngt...SCA...Pt Reyes to Pigeon Pt 0-10 nm until 3 PM
             SCA...Pigeon Pt to Pt Pinos 0-10 nm until 3 PM
             SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm until 3 PM
             SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm until 3 PM
             GLW...Pt Reyes to Pigeon Pt 0-10 nm until 9 PM
             GLW...Pigeon Pt to Pt Pinos 0-10 nm until 9 PM
             GLW...Pt Pinos to Pt Piedras Blancas 0-10 nm until 9 PM
             GLW...Pigeon Pt to Pt Piedras Blancas 10-60 nm until 9 PM
             GLW...Pt Arena to Pt Reyes 0-10 nm until 9 PM
             GLW...Pt Arena to Pigeon Pt 10-60 nm until 9 PM
             SCA...Mry Bay
             SCA...SF Bay until 3 AM

&&

PUBLIC FORECAST: RGass
AVIATION: DK
MARINE: DK

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