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000
FXUS66 KMTR 271941
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1241 PM PDT Sat May 27 2023

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

.SYNOPSIS...
Issued at 1209 PM PDT Sat May 27 2023

Overall pattern remains largely unchanged with unseasonably cool
temperatures throughout the forecast period. Typical morning
clouds with inland clearing each afternoon. The long term outlook
suggests this pattern will likely persist into early June.

&&

.SHORT TERM...
(This evening through Sunday)
Issued at 1209 PM PDT Sat May 27 2023

The flow has become more zonal today between systems as the
previous trough moves out and the next closed low starts to move
in. Current satellite showing slightly more clearing today in
comparison to previous days. The morning sounding shows the
marine layer slightly compressed as expected, though still deep
(~2200 feet) when compared to a typical shallow marine layer in
our region. All in all, today is expected to be the warmest day on
a regional scale, but little variation is expected in daily high
temps for much of our area near coastal zones. As the next low
starts to move in tonight, expect the marine layer to deepen once
again with more rounds of drizzle Sunday morning for coastal
areas, including favored shallow upslope areas such as the
Petaluma Gap, East Bay east of the Golden Gate Gap, Santa Cruz
Mtns, and the Big Sur Coast. There is a low probability (10-20%)
for a couple of isolated showers and thunderstorms in far northern
Sonoma and Napa counties Sunday afternoon. As it looks now, any
deep vertical development will likely be hindered by the marine
layer not quite mixing out completely, thus providing a capping
inversion through the afternoon.

&&

.LONG TERM...
(Sunday night through next Friday)
Issued at 1209 PM PDT Sat May 27 2023

The longer term pattern appears to be largely that of persistence
as well with small day-to-day changes. Patchy drizzle can be
expected during the mornings through midweek. There are some hints
at a slight warming trend into the end of the week as the
aforementioned closed low moves out of the area. Overall, the
pattern looks to persist with troughing off the west coast
amplified by a strong ridge of high pressure over central Canada.

&&

.AVIATION...
(18Z TAFS)
Issued at 1107 AM PDT Sat May 27 2023

Current satellite imagery shows stratus beginning to recede,
though many terminals are still under MVFR CIGs. Expect clearing
and VFR for coastal terminals later in the day, towards 20Z, with
inland terminals clearing closer to between 18Z and 19Z. Stratus
then looks to make a return in the mid to late evening today,
bringing back MVFR CIGs. Winds increase into the afternoon to
become breezy before weakening into the night as stratus pushes
in. IFR CIGs become possible for coastal terminals in the early
morning hours of Sunday, before returning to MVFR in the late
morning. Best chances of IFR conditions overnight are at Monterey
Bay terminals.

Vicinity of SFO...Clearing expected to VFR around 20Z for a brief
time, before returning to MVFR CIGs around 01Z Sunday. MVFR
conditions last through the night, with chances of IFR beginning
near 03Z and lasting until about 16Z. Chances of going IFR
currently stand at about 50% for this time frame, so have included
in the TAF at this time, though will have to watch closely.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...MVFR expected to last until around 21Z.
VFR window beyond 21Z appears to be limited, with stratus and low
CIGs making a return towards 01Z, though scattered low clouds
will still be present in the VFR time frame. A 53% chance of IFR
conditions exists between 01Z and 16Z, so have included in the TAF
at this time. Winds increase into the afternoon to become onshore
around 9-12 knots, with occasional gusts up to 17 knots at KSNS.
Winds dissipate into the night to become light.

&&

.MARINE...
(Tonight through next Thursday)
Issued at 1209 PM PDT Sat May 27 2023

Moderate northwest winds will prevail with the strongest out over
the northern coastal waters through Memorial Day. Breezy to gusty
westerly winds across the San Francisco Bay, San Pablo Bay,
Suisun Bay, the Delta in the afternoons before diminishing into
the night. A series of moderate to long period southerly swells
will also persist into early next week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 9 PM this evening to 9 AM PDT Sunday
     for PZZ540-575.

     Small Craft Advisory until 3 PM PDT Sunday for PZZ570.

&&

$$

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

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