Petaluma, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

835
FXUS66 KMTR 231604
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
904 AM PDT Wed Apr 23 2025

...New UPDATE, MARINE...

.SYNOPSIS...
Issued at 1224 AM PDT Wed Apr 23 2025

A pattern change brings cooler conditions today with the cooling
trend continuing into the weekend. Patchy drizzle and fog are
possible within the marine layer clouds. Light rain and drizzle are
possible throughout the region Friday and Saturday.

&&

.UPDATE...
Issued at 904 AM PDT Wed Apr 23 2025

Foggy and overcast conditions continue across much of the Bay Area
and Central Coast. Both the 12Z OAK sounding and Fort Ord Profiler
show a deep marine layer between 2500-3000 ft. This matches well
with the fairly extensive stratus coverage across the coast and
interior areas. The marine layer is expected to remain fairly deep
throughout today with low confidence that overcast skies will clear
along the SF Bay Shoreline and along the coast. HREF guidance
indicates some potential for clearing across inland areas this
afternoon/evening before widespread overcast conditions return
overnight. Cooler conditions to prevail today as the weather starts
to become more unsettled with highs in the upper 60s to low 70s
across the interior and mid 50s to low 60s along the coast.

&&

.SHORT TERM...
(Today and tonight)
Issued at 1224 AM PDT Wed Apr 23 2025

A shortwave trough is building over the West Coast, resulting in
cooler temperatures and a deeper marine layer in the region.
Satellite imagery shows stratus developing along the coast from
Point Reyes southward, moving inland into the Bayshore East Bay,
across the Monterey Bay region, and down through the Salinas Valley
and across the Gilroy-Hollister region. The enhanced marine layer
will enable the stratus to develop further inland through the night,
before the inland stratus gradually dissipates through the morning,
while some coastal regions remain socked in through the day. Breezy
onshore flow will develop this afternoon, with gusts reaching 20-25
mph through the gaps and passes. High temperatures today will top
out in the upper 60s to the lower 70s in the inland valleys, and the
middle 50s to lower 60s along the Bays and Pacific coast.

&&

.LONG TERM...
(Thursday through Tuesday)
Issued at 1224 AM PDT Wed Apr 23 2025

Thursday is shaping up to be pretty similar to today, with an uptick
in wind gusts (reaching 25-30 mph through the gaps and passes) and a
downtick in inland high temperatures (middle to upper 60s).

Friday and Saturday should see the arrival of a deepening upper
level trough coming through the eastern Pacific. Confidence has
continued to increase in the stronger model solutions and a
potential cutoff low coming into California. Combined with a
southward trend in the forecast track, the trend has resulted in an
increase in PoPs throughout the region, especially south of the
Golden Gate. The current forecast has PoPs rising as high as 40-50%
Friday night and Saturday morning. Rainfall totals remain low;
although the exact spatial extent of the rainfall is quite
uncertain, we`re not expecting totals above a tenth of an inch in
the valleys and a quarter of an inch in the higher elevations.
Something else to keep an eye on: we`re starting to see some
indications of thunderstorm potential on Friday evening into
Saturday morning, with NBM model output putting odds of thunderstorm
activity as high as 10-15%. We`ll monitor how the thunderstorm risk
evolves over the next couple of days. As for high temperatures on
Friday and Saturday, expect anywhere from the middle 50s to the
middle 60s in the lower elevations, and the middle 40s to the lower
50s in the higher elevations.

Ridging should return after the trough moves out, with daytime highs
rebounding to near the seasonal average in the early part of next
week.

&&

.AVIATION...
(12Z TAFS)
Issued at 506 AM PDT Wed Apr 23 2025

Widespread MVFR CIGS are affecting the region with pockets of fog at
STS. HAF will see IFR CIGs further into the morning with moments of
IFR CIGs and slight reductions in visibilities for the Monterey Bay
as well. Cloud cover begins to erode in the late morning and into
the afternoon, but remains on the coast, with HAF seeing CIGs
through the TAF period. Winds stay light to moderate through the
morning, and increase into the afternoon before reducing again over
the evening. MVFR/IFR CIGS build along the coast and begin to push
inland into the evening with CIGs becoming widespread into the late
night.

Vicinity of SFO...MVFR CIGS linger until the early afternoon. Skies
clear as breezy west winds build into the afternoon. These winds
will reduce in the evening, but stay moderate as MVFR CIGs fill.
CIGs fall to IFR levels into early Thursday morning.

SFO Bridge Approach...Expect CIGs to retreat slightly sooner than at
SFO today, and return slightly later than SFO tonight.

Monterey Bay Terminals...MVFR and moments of IFR CIGS last through
the late morning before CIGs retreat back into the Monterey Bay and
moderate west winds build. Cloud cover only manages to scatter at
MRY, while SNS see clearing skies for the afternoon. Winds reduce
into the late afternoon and early evening with MVFR CIGs moving
inland and filling over the terminals.

&&

.MARINE...
(Today through Monday)
Issued at 904 AM PDT Wed Apr 23 2025

Strong northwesterly breezes and rough seas can be expected for
the outer waters today. Conditions improve tomorrow with light
rain chances Friday into Saturday. Strong northwesterly breezes
and rough seas return Saturday afternoon.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 AM PDT Thursday for Pigeon Pt to Pt
     Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm.

     Small Craft Advisory from 3 PM this afternoon to 3 AM PDT
     Thursday for Pt Pinos to Pt Piedras Blancas 0-10 nm.

     Small Craft Advisory until 3 PM PDT Thursday for Pt Arena to Pt
     Reyes 10-60 NM.

&&

$$

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

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