Nicasio, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

115
FXUS66 KMTR 011812
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1112 AM PDT Thu May 1 2025

...New AVIATION, MARINE...

.SYNOPSIS...
Issued at 108 AM PDT Thu May 1 2025

Fairly standard weather continues through Friday with warm inland
temperatures and cooler, cloudy weather in the marine layer. A
disturbance will bring strong winds and cooler temperatures
Saturday.

&&

.SHORT TERM...
(Today and tonight)
Issued at 108 AM PDT Thu May 1 2025

The enhanced IR satellite view shows extensive marine layer
stratus across the Bay Area and Central Coast. Interestingly the
stratus is filling the Salinas Valley all the way to Paso Robles,
while further north it`s hardly reaching the East Bay. This
suggests the marine layer depth is not uniform. The Ft. Ord
profiler reveals a depth of 2,500 feet in Monterey County,
compared to 1,000-1,500 feet near the San Francisco Bay according
to the PGE-WRF. This depth difference is caused by a weak
disturbance in the 500 mb ridge over Southern California, while
the ridge axis moves over Northern California. Basically there is
less air pushing down on the marine layer over the Central Coast
compared to the Bay Area, which is allowing the marine layer to
expand deeper with decreasing latitude. The pattern is pretty slow
to evolve through the day, and this trend will likely hold.
Inland and higher elevation areas will have another nice day in
the mid 70s with plenty of sunshine. There is a slight chance of
convection, mainly east and south of the Bay Area, though SPC has
placed southern Monterey and San Benito counties in a general
thunder risk today. With cold air aloft there is good instability
this afternoon (HRRR shows 1000 J/kg of CAPE at Paso Robles), but
it`s elevated above some moderate inhibition, and the CAMs don`t
show any activity developing.

&&

.LONG TERM...
(Friday through Wednesday)
Issued at 108 AM PDT Thu May 1 2025

By Friday a long wave trough will begin to approach the coast.
This system has been slowing down in recent model runs, which
should allow the relatively good weather to continue through
Friday before the cold front brings overcast skies Friday night.
Any rain associated with this system should be very light as the
PWAT only reaches around 0.8" and the moisture plume is pretty
narrow and fast moving ahead of the surface front. By the time the
sun comes up on Saturday, the front may have already passed
allowing the skies to gradually clear through the day as much
drier air filters in. By far the biggest impact will be strong NW
winds in the post-frontal environment. Subtropical high pressure
will build over the Eastern Pacific while the surface low
associated with the cold front moves N-S across Eastern
California. The gradient between these two features will support
wind speeds of 15-30 mph with gusts as high as 35-50 mph. The
strongest winds will be along the coast Saturday afternoon. Strong
winds will persist Sunday as the low bottoms out around 1004 mb
near Las Vegas Sunday morning. Despite the wind, the skies will be
clear and temperatures will start to rebound. Improvement
continues into next week with offshore winds possible Monday and
a new ridge becoming established mid-week. Temperatures will
return to a nice seasonal normal and the marine layer may even
take a few days off to give coastal areas some sunshine.

&&

.AVIATION...
(18Z TAFS)
Issued at 1058 AM PDT Thu May 1 2025

Marine layer has thinned/cleared most terminals with Monterey Bay
still holding strong. That being said, Monterey Bay terminals are
at least showing some thinning on the edges, which is better than
24 hours ago. Do expect VFR all terminals this afternoon, except
KHAF, which will still be in the soup with cigs AOA 1k feet. No
major shift tonight so brought cigs back in with mid morning
clearing on Friday. Winds Friday afternoon/evening will increase.
Overall confidence is moderate.

Vicinity of SFO...VFR with onshore flow. Will bring cigs back in
06-08Z tonight. Guidance shows SFO being on the fringes of patchy
cigs early with filling in by morning. Friday AM rush clearing
with gusts over 20kt by Friday afternoon.

SFO Bridge Approach...Could see a little less cloud coverage over
approach on Friday if some of the guidance is correct. Lower
confidence on this verifying.

Monterey Bay Terminals...MVFR cigs lingering 19-20Z this
afternoon. MRY will be last to clear. Cigs return this evening and
then remain through 18Z Friday.

&&

.MARINE...
(Today through Tuesday)
Issued at 1058 AM PDT Thu May 1 2025

Persistant northwesterly flow with moderate to locally strong
winds resulting in steeper winds waves through Friday. Widespread
hazardous marine conditions are expected over the weekend and
into early next week in the form of gale-force northerly winds
with up to storm-force gusts possible. Rough to very rough seas
are also forecast for the weekend.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 3 PM Friday to 9 AM PDT Saturday for
     SF Bay N of Bay Bridge.

     Small Craft Advisory from 9 AM Friday to 9 AM PDT Saturday for
     Mry Bay-Pigeon Pt to Pt Pinos 0-10 nm-Pt Reyes to Pigeon Pt
     0-10 nm.

     Gale Watch from Saturday morning through late Saturday night for
     Mry Bay.

     Small Craft Advisory from 3 AM Friday to 9 AM PDT Saturday for
     Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm-
     Pt Pinos to Pt Piedras Blancas 0-10 nm.

     Gale Watch from Saturday morning through Sunday morning for
     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.

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

&&

$$

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

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