194
FXUS66 KMTR 081952
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1252 PM PDT Sat Jun 8 2024

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

.SYNOPSIS...
Issued at 1205 PM PDT Sat Jun 8 2024

Seasonal temperatures with breezy onshore winds will last through
Sunday before another warm up begins Monday.

&&

.SHORT TERM...
(This evening through Sunday)
Issued at 1205 PM PDT Sat Jun 8 2024

The stratus clouds have eroded everywhere except along the
immediate coast. Despite the clearing, area profilers and the
morning sounding confirm the marine layer is roughly 2,000 ft
deep. This is allowing cool air to infiltrate into the valleys
and keep the afternoon temperatures mild.

A short wave trough at 500 mb is approaching the coast this
afternoon. This wave will amplify and become a cut-off low SW of
the Channel Islands by Sunday evening. This synoptic change will
cause the mid-level winds to shift from southerly to northerly
over the next 36 hours. This change won`t be as obvious at the
surface. While the surface wind direction should veer a bit, the
weather Sunday will continue to be dominated by a deep marine
layer, morning stratus, and breezy onshore winds in the afternoon.
Broadly speaking, the temperatures Sunday will be similar to
Saturday and the seasonal averages.

&&

.LONG TERM...
(Sunday night through next Friday)
Issued at 1205 PM PDT Sat Jun 8 2024

Abandoned by the jet stream, the Southern California cut-off low
will continue to drift south Monday, allowing a ridge of high
pressure to build across the Bay Area. This ridge will cause the
marine layer to compress from 2,000 ft over the weekend to around 1,000
ft by Tuesday. While the cut-off low is part of the typical
offshore wind equation, we are missing the other piece of the
puzzle; strong high pressure over the intermountain West. While
weak offshore winds are expected at 700 mb Mon-Tue, they likely
won`t reach the surface. The combination of offshore winds aloft,
and a shallow marine layer will cause inland areas to warm above
seasonal averages from Monday through Wednesday. Tuesday currently
looks like the warmest day of the week, with inland highs in the
90s. Coastal areas will stay in the 60s and 70s.

By Thursday, an approaching trough will kick the cut-off low
inland, where it will quickly weaken. This will bring the return
of onshore flow and allow temperatures cool back to the seasonal
average.

&&

.AVIATION...
(18Z TAFS)
Issued at 1032 AM PDT Sat Jun 8 2024

Coastal stratus is eroding and VFR conditions will prevail through
the remainder of the day. Moderate SW winds will prevail in the
North Bay, with NW winds at SJC and westerly winds elsewhere.
MVFR-IFR stratus will return to most terminals overnight.

Vicinity of SFO...VFR under high clouds. WNW winds will be
moderate to strong this afternoon, and will remain fairly
consistent once they get started. The big question at SFO is if
ceilings will return overnight. The TAF keeps it clear for now,
but there is a 20-30% chance of a low MVFR ceiling in the early
morning hours Saturday, similar to what was observed this morning.
OAK has a better chance, and MVRF ceilings were included in the
TAF from 13-17Z Sunday.

SFO Bridge Approach...The bridge approach will likely stay clear
of low clouds, even if SFO and OAK develop ceilings Sun morning.

Monterey Bay Terminals...MVFR ceilings are lingering, but the
visible satellite loop shows they will soon break at both MRY and
SNS. VFR conditions are likely for about 9-12 hours before the
stratus returns this evening. GFSLAMP shows a 15% chance of LIFR
ceilings developing around 12Z at MRY, and with subtle
compression expected in the marine layer, the ceilings may drop
lower than they were this morning (OVC006). Otherwise, moderate
onshore winds will persist through the TAF period.

&&

.MARINE...
(Today through Thursday)
Issued at 1032 AM PDT Sat Jun 8 2024

The gradient between subtropical high pressure and lower pressure
over the SW US is supporting a moderate to fresh NW breeze. As the
high pressure slowly encroaches towards the coast, the pressure
gradient will tighten, causing the wind speed to increase through
the weekend. A fresh to strong NW breeze will persist through
next week with the potential for gale force winds by next weekend.
Significant wave heights will mostly be dominated by wind driven
waves, though there is a moderate NW swell and a low SW swell
mixed in.

&&

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

     Small Craft Advisory until 9 AM PDT Monday for Pt Arena to Pt
     Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM.

     Small Craft Advisory until 3 AM PDT Monday for Pt Reyes to
     Pigeon Pt 0-10 nm.

     Small Craft Advisory from 3 PM Sunday to 3 AM PDT Monday for Pt
     Pinos to Pt Piedras Blancas 0-10 nm.

     Small Craft Advisory until 9 AM PDT Monday for Pigeon Pt to Pt
     Pinos 10-60 NM.

&&

$$

SHORT TERM...Flynn
LONG TERM....Flynn
AVIATION...Flynn
MARINE...Flynn

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