348
FXUS66 KMTR 160004
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
502 PM PDT Sun Sep 15 2024

...New AVIATION, MARINE...

.SYNOPSIS...
Issued at 112 PM PDT Sun Sep 15 2024

Gusty winds continue today, with chances of drizzle and light rain
arriving later tonight into Monday afternoon. Temperatures below
seasonal averages continue through midweek with a second upper level
low moving in, then gradual warming into the next weekend.

&&

.SHORT TERM...
(This evening through Monday)
Issued at 112 PM PDT Sun Sep 15 2024

The weather pattern today is dominated by a cold front working
through the Bay Area and into the Central Coast. The cold front has
brought noticeable cooler temperatures across the board, with highs
reaching the low to mid 70s in the inland valleys, the upper 70s to
low 80s in the North Bay valleys and southern Monterey County, the
mid to upper 60s in the Bayshore, and the upper 50s to mid 60s along
the Pacific coast. Monday is set to be even cooler inland, with even
the North Bay valleys and southern Monterey County seeing
temperatures in the low to mid 70s.

Northwest winds should continue to build through the day, with the
strongest gusts tonight into early Monday morning before winds
diminish later in the morning through the afternoon. The strongest
gusts will be through the gaps, passes, and favorably oriented
(northwest-southeast) valleys and coastal regions (e.g. the Salinas
Valley, the San Bruno Gap, the Sonoma Coast, and the Santa Cruz
County coast west of Capitola). These areas will see gusts up to 35-
40 mph, occasionally 45-50 mph. The rest of the region should see
gusts of 25-35 mph.

Chances of drizzle and light rain arrive late tonight into Monday
afternoon, but accumulations are expected to be pretty light. The
higher elevations are expected to see a tenth to a quarter of an
inch of rain, with some isolated areas seeing nearly half an inch.
The forecast for the lower elevations continues to be even lighter,
with a tenth of an inch being the absolute maximum and the North Bay
and southern Monterey County largely missing out.

Low clouds continue to linger across the San Francisco Bay Area and
the southern Monterey Bay. Some clearing is possible through the
afternoon, but the cooler temperatures could keep stratus around at
the immediate coast and some of the higher elevations. Tonight, the
strong winds and rain make for a pretty low confidence forecast for
stratus coverage, with the best forecast suggesting more mid-level
cloud cover across the region.

&&

.LONG TERM...
(Monday night through next Saturday)
Issued at 112 PM PDT Sun Sep 15 2024

Temperatures cooler than seasonal averages continue through the next
few days, and another upper level low arrives late Tuesday into
Wednesday. This low isn`t as strong as the one that`s coming through
today, so the winds won`t be as gusty, and rainfall totals will be
similar to those from the system today and Monday. Of note, the
National Blend is trying to slip a very low chance (10-15%
probability) for thunderstorms for the Wednesday system, and a
cursory look at the K-Index suggests that, with values up to 32
across the region, the potential for isolated thunderstorms
exists. Not very confident at this stage for anything to happen,
but definitely something to keep an eye on for the next couple of
days as the forecast is refined.

After the upper level low moves out, the pattern shifts to a slight
ridge with temperatures close to or slightly above seasonal averages
by the weekend, and the CPC outlooks suggest that the seasonal to
warm temperatures continue into the last weekend of September.

&&

.AVIATION...
(00Z TAFS)
Issued at 502 PM PDT Sun Sep 15 2024

It`s MVFR-VFR with increasing areas of strong and gusty west-
northwest winds. Surface winds are generally coupled to winds
aloft this afternoon during maximum diurnal mixing. Expect turbulent
conditions however due to vertical mixing of winds non-convective
low level wind shear (llws) should remain minimal; for now llws not
advertised in the 00 TAFs, will amend if this changes based on pilot
reports (pireps), etc. Cold air advection with the incoming low
pressure system to our north will periodically result in a few areas
of some downsloping and lee- side warming over the Bay Area terrain.
With the low center passing over the Bay Area tonight and Monday
morning a few showers will develop as well.

Vicinity of SFO...Gusty west wind continuing this evening, gusts
recently have approached 40 knots. VFR-MVFR during the period. A
few showers developing tonight and Monday morning.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Gusty west to northwest winds 15 to 30 knots
continuing this evening. VFR-MVFR during the period. A few showers
developing tonight and Monday morning.

&&

.MARINE...
(Tonight through next Friday)
Issued at 438 PM PDT Sun Sep 15 2024

Back to back early season cold fronts will move through the
coastal  waters today and Wednesday resulting in widespread strong
northwesterly breezes with near gale force gusts. In addition,
there  is also up to a 10% chance for thunderstorms which could
produce  lightning, locally heavy rainfall, and locally stronger
winds. Seas  will remain rough outside of protected waters through
the forecast  period.

&&

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

     Gale Warning until 3 AM PDT Monday for Pt Arena to Pt Reyes 0-10
     nm.

     Gale Warning until 9 PM PDT this evening for Pt Pinos to Pt
     Piedras Blancas 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.

     Small Craft Advisory until 9 AM PDT Monday for Pigeon Pt to Pt
     Pinos 0-10 nm.

     Gale Warning until 3 PM PDT Monday for Pt Arena to Pt Reyes 10-
     60 NM.

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

&&

$$

SHORT TERM...DialH
LONG TERM....DialH
AVIATION...Canepa
MARINE...Sarment

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