551
FXUS66 KMTR 282314
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
414 PM PDT Sat Jun 28 2025

...New AVIATION...

.SYNOPSIS...
Issued at 214 PM PDT Sat Jun 28 2025

June Gloom continues to bring cloudy coastal conditions, sunny
afternoons, and cloud evenings. The overall pattern remains fairly
steady through next week as June Gloom persists and a slight
cooling trend begins across the interior Sunday.

&&

.SHORT TERM...
(This evening through Sunday)
Issued at 214 PM PDT Sat Jun 28 2025

The marine layer looks to remain around 1200-1500 ft tonight as
zonal flow briefly develops before weak upper level troughing
returns Sunday. Highest confidence in overcast conditions directly
along the coastline but patchy cloud cover is likely to move into
portions of the North Bay and SF Bay Shoreline overnight as the
marine layer expands. The arrival of upper level troughing on Sunday
will deepen the marine layer to around 2000 ft throughout the day on
Sunday and allow cloud cover to expand across much of the interior
by Sunday night. Temperatures cool slightly, in comparison to today,
on Sunday with high temperatures at most sites cooling by 2 to 3
degrees. For areas above 1000-1500 ft, bumped Sunday`s high
temperatures up by a few degrees in order to compensate for the lack
of marine layer influence across the higher elevations. High
temperatures will generally be in the 80s across the interior lower
elevations and upper 80s to mid 90s across the higher elevations.
Closer to the coastline, cooler temperatures in the upper 50s to 60s
prevail. When looking at how these temperatures differ from normal,
temperatures within the marine layer are generally seasonal to
slightly below normal whereas temperatures above the marine layer
are running seasonal to slightly above normal. A fairly typical June
Gloom pattern continues through the remainder of the long term
forecast as upper level troughing persists into next week.

&&

.LONG TERM...
(Sunday night through next Friday)
Issued at 214 PM PDT Sat Jun 28 2025

A slight cooling trend begins Monday and Tuesday as upper level
troughing deepens and develops a cut-off low as it pushes into the
Central Coast. This will help drop interior temperatures into the
upper 70s to mid 80s with only the highest elevations lingering in
the upper 80s to mid 90s. By Wednesday, the cut-off low will have
weakened and shortwave ridging looks to develop across the Bay Area.
Guidance has been going back and forth as to if this shortwave ridge
will develop or if the upper level flow will become more zonal.
Either way, temperatures look to stay fairly similar to those on
Mon/Tues but a few locations may experience a few degrees (2-3) of
warming. As we head into Thursday and Friday, upper level troughing
returns and will cool temperatures down into the 80s across the
interior and mid 50s to mid 60s along the coastline. In terms of our
cloud cover forecast, persistent upper level troughing will
result in a continuation of our June Gloom pattern and see us
transition into No Sky July. For coastal areas and portions of the
interior (particularly Monday - Wednesday), expect stratus to
return each night and clear out mid to late morning. Coastal areas
see some potential for drizzle Sunday morning and again Monday
morning as the cut-off low arrives but not currently expecting any
accumulating precipitation.

There is a very low (2-5%) chance of thunderstorms developing in the
afternoon/evening hours across the North Bay Interior Mountains
Monday and Tuesday as the cut-off low moves through the Central
Coast. The main lightning threat is well to our north in NWS
Eureka`s CWA but there is still some potential across far northern
Sonoma and Napa counties. Guidance shows a few hundred joules of
most unstable CAPE and CINH present during the afternoon/evening
with Tuesday afternoon looking more favorable than Monday. 700-500
mb lapse rates do show some conditional instability with forecast
lapse rates between 7 to 8 degrees C/km. However, while there is
some mid-level moisture present, it seems it may be a limiting
factor for any storms approaching the North Bay. The bulk of the
moisture associated with this cut-off low will stay well to our
north with PWAT values around only 0.55 inches to 0.7 inches across
northern Sonoma and Napa while PWAT values are around 1 inch to our
north in northern CA. All that being said, thunderstorm chances are
non-zero for far northern Sonoma and Napa counties Monday and
Tuesday, but, storms are unlikely to develop with chances remaining
very low between 2 to 5%.

&&

.AVIATION...
(00Z TAFS)
Issued at 414 PM PDT Sat Jun 28 2025

IFR-LIFR stratus persists at the immediate coast with southerly
winds, while VFR and generally onshore flow continues inland.
Stratus will flow into the coastal valleys tonight through Sunday
morning with the inland terminals remaining clear. Low confidence
for a ceiling at SJC, have kept the TAF VFR for now. The southerly
flow along the coast resumes Sunday afternoon, with an onshore wind
pattern persisting at the terminals.

Vicinity of SFO... VFR through the evening with IFR stratus
developing overnight. Observed winds have shifted to the northwest,
which is reflected in the current TAF, and will remain breezy
through the evening hours before becoming light overnight. A brief
period of light northeast flow is possible on Sunday morning, but
generally westerly flow should resume by the afternoon.

SFO Bridge Approach... Similar to SFO.

Monterey Bay Terminals... Clear conditions and breezy northwest
winds at the terminals for the next few hours. SNS may see an IFR
ceiling before MRY with the strong southerly flow pushing stratus
into the Salinas Valley and helping keep MRY clear, with both
terminals expected to mix out through Sunday morning. Light winds
overnight before breezy onshore flow resumes Sunday afternoon.

&&

.MARINE...
(Tonight through next Thursday)
Issued at 214 PM PDT Sat Jun 28 2025

Fresh northwesterly breezes will continue over the outer waters
north of Point Reyes through Sunday while southerly winds prevail
along the coast south of Point Reyes. Significant wave heights
gradually subsiding tonight into Sunday as winds ease. The next
round of elevated wave heights, strong northwesterly breezes, and
moderate to rough seas begins Tuesday and continues through late
next week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 9 AM PDT Sunday for Pt Arena to Pt
     Reyes 10-60 NM.

&&

$$

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

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