Pacheco, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

537
FXUS66 KMTR 021944
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1244 PM PDT Fri May 2 2025

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

.SYNOPSIS...
Issued at 1231 PM PDT Fri May 2 2025

A cold front will move through this evening, bringing
cooler temperatures, overcast skies, and a slight chance for rain.
Behind the front, strong NW winds will persist through the weekend.
These strong winds will flip offshore by Monday before easing
through the week as warmer temperatures return.

&&

.SHORT TERM...
(This evening through Saturday)
Issued at 1231 PM PDT Fri May 2 2025

Key Messages

    -Strong NW winds Saturday
-Coastal gusts 40-50 mph
-Inland gusts 30-40 mph

Fairly standard marine layer conditions will persist through the
afternoon before a cold front moves through overnight. High clouds
will start to arrive before the sun goes down. Through the night
these clouds will lower into a widespread stratus bank, which could
produce a few terrain enhanced rain drops. For some reason the NBM
continues to insist the chance for rain is less than 3%, but several
high resolution models are showing a few hundreths of rain and
the dynamics seem to support this with a narrow band of 0.8 PWAT.
To account for this, I used ECMWF POP, which is generally above
the 15% threshold needed to be mentioned explicitly in our
forecast products. The biggest impact from this system will be
strong NW winds that last through the weekend. These winds are
caused by the gradient between building high pressure over the
subtropical East Pacific and deepening low pressure over the
Rockies. Since the driver is the synoptic scale pressure
gradient, the strong winds will persist for a couple days. Coastal
areas will see the greatest impacts, where gusts could reach 50
mph at times.

&&

.LONG TERM...
(Saturday night through next Thursday)
Issued at 1231 PM PDT Fri May 2 2025

Key Messages

- Strong NW winds continue through Sunday
- Winds flip offshore Sunday night, increasing fire danger for
  interior portions of the North and East Bay

Skies will begin to clear behind the front Saturday afternoon as
the strong winds persist. There is a chance for afternoon showers
with cold air aloft decreasing the thermodynamic stability,
however it will be hindered by a much drier air mass. As the low
drifts south Sunday, the overall gradient will not change much and
the strong winds will only ease by a few mph. By Sunday night
troughing will develop over the central/southern California
coast with building high pressure over NE California and NW
Nevada. This will cause the strong winds to flip from onshore NW
to offshore NE in the higher terrain of the interior North and
East Bay. This pattern brings some fire weather concerns, but the
fuel moisture is still relatively high compared to the peak of
fire season. The gradient will relax by Tuesday as large scale
ridging returns and winds finally calm. More typical conditions
with warm afternoon temperatures inland and marine layer stratus
along the coast will return for the remainder of the week.

&&

.AVIATION...
(18Z TAFS)
Issued at 1044 AM PDT Fri May 2 2025

The marine layer is eroding nicely this afternoon and the 18Z TAFs
begin with most terminals in VFR conditions. These clear skies
will persist for several hours before high clouds arrive this
evening ahead of a cold front. The ceilings will drop to
MVFR/IFR through the night, and there is a slight chance for
rain. Outside of flight conditions, this front will usher in
strong NW winds that will persist in the post-frontal environment
through the weekend.

Vicinity of SFO...SFO ceilings have been trying to clear this
morning, but persistent moisture is keeping a steady stream of
broken low clouds moving across the Peninsula. I`ve included a
tempo line to show the uncertainty between scattered and broken
ceilings through the middle of the day. High clouds will gradually
lower through the night, with possible IFR ceilings Saturday
morning. Strong NW winds will persist through the TAF period and
beyond, with gusts likely reaching 35KT Saturday afternoon.

SFO Bridge Approach...The approach over the bay has been much
more clear than departures over the peninsula, and that trend
looks to continue for the next several hours.

Monterey Bay Terminals...Low confidence ceiling forecast in the
short term. The visible satellite is encouraging for Salinas over
the next hour or 2, but MRY is another story. There are patches of
clear sky, but a persistent stratus bank offshore is
demonstrating that marine layer moisture is enough to support MVFR
ceilings through the day before the cold front brings more
widespread ceilings this evening.

&&

.MARINE...
(Today through Wednesday)
Issued at 905 AM PDT Fri May 2 2025

An approaching cold front will cause NNW winds to gradually
increase to gale force by Saturday evening. These winds will
persist through Sunday, building very rough seas.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 9 AM PDT Saturday for SF Bay N of Bay
     Bridge.

     Small Craft Advisory from 3 PM Saturday to 3 AM PDT Sunday for
     SF Bay N of Bay Bridge.

     Small Craft Advisory until 9 AM PDT Saturday for Mry Bay-Pigeon
     Pt to Pt Pinos 0-10 nm-Pigeon Pt to Pt Pinos 10-60 NM-Pt
     Arena to Pt Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM-Pt
     Pinos to Pt Piedras Blancas 0-10 nm-Pt Reyes to Pigeon Pt 0-
     10 nm.

     Gale Warning from 9 AM Saturday to 3 AM PDT Sunday for Mry Bay.

     Gale Warning from 9 AM Saturday to 3 PM PDT Sunday for Pt Arena
     to Pt Reyes 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm.

     Gale Warning from 9 AM Saturday to 9 AM PDT Sunday for Pigeon Pt
     to Pt Pinos 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.

     Gale Warning from 9 AM Saturday to 9 PM PDT Sunday for Pigeon Pt
     to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM.

&&

$$

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

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