009
FXUS66 KMTR 291623
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
923 AM PDT Sun Jun 29 2025

...New UPDATE and SYNOPSIS...

.SYNOPSIS...
Issued at 923 AM PDT Sun Jun 29 2025

An upper low off the coast will keep onshore winds in place
through much of the week. Inland temperatures will cool back to
more seasonably warm weather with milder temperatures near the
coast as the marine layer will persist bringing night and morning
clouds.

&&

.UPDATE...
Issued at 923 AM PDT Sun Jun 29 2025

No updates planned for this morning. The low clouds have already
pulled back to the coast/beaches. Current marine layer depth is
around 1000 feet which has led to some morning fog and low cigs at
coastal airports. A nice Sunday in store for most of the Bay Area
with model guidance suggesting inland areas will have a modest
cool down as onshore flow increases this afternoon as upper low
off the coast gets a little closer. That low will have impacts
across the state the next few days that we`ll continue to monitor
closely. In the short term expect more convection over the Sierra
this afternoon with evening debris clouds from those storms
forecast to rotate across the North Bay this evening. The presence
of the low will help to induce more widespread convection Monday
and Tuesday for Northern California but at this time we are not
forecasting storms for the Bay Area with chances remaining less
than 5% over the far North Bay. We will continue to monitor for
any changes over the next several days. Otherwise the low will
cause an inland cool down early in the work week with near normal
temps beyond that.

&&

.SHORT TERM...
(Today and tonight)
Issued at 306 AM PDT Sun Jun 29 2025

The marine layer expansion is beginning and has made for a night of
increases coastal drizzle and fog, along with a much more far
reaching push of marine stratus inland. The Salinas Valley is
showing much more cloud intrusion than the last few nights and the
North Bay valleys are also beginning to see that cloud cover filter
in.

The feed and the thickness of the morning cloud cover will make it
slower to erode than previous days, but everywhere aside from the
immediate coast should see clearing skies around noon. This will
mean that some of those valleys that stayed clear in the morning
over the last few days will be slightly cooler from the reduced
amount of time in the sun. Highs will be largely the same for the
immediate coast (upper 50s to low 60s) as well as the interior (80s
and 90s for the far interior) but with slightly improved humidities.
Winds look to be moderate to breezy into the afternoon and evening
with cloud cover quick to rebuild in the evening.

&&

.LONG TERM...
(Monday through Saturday)
Issued at 306 AM PDT Sun Jun 29 2025

The slow moving low and trough combo focuses over the region through
Sunday and just about grinds to a halt for Monday. This will keep of
the onshore flow and settle the marine layer to around 2000 ft and
allow for the marine influence to spread fairly far inland.

There is an interesting factor that this low is adding to the
forecast mix: the very slight potential for convection pulling into
the North Bay Mtns. Farther north as well as into the Sacramento
Valley, these chances look far better, but were`re still setting up
with a non-zero chance for thunderstorms in the North Bay (2-5%)
Monday and again Tuesday. Our chances remain lower because our
cooler and more stable environment will be working hard against
anything developing, or sustaining anything moving into Bay Area
from the north.

Outside of that excitement, the forecast really settles into a steady
daily pattern. The low and trough combo lasts into the mid week and
gets replaced by another troughing pattern. This will keep our
marine layer fairly well established around the 2000 ft mark with
the nightly inland pushes leading to far reaching low cloud cover.

So the pattern of:
-cloudy mornings with breezy, sunny afternoons inland areas
-constantly cloudy coasts
-warm, dry interior areas

continues through the forecast with only some slight variations on
the clearing times for the inland areas affecting high temperatures
and the change in flow slightly reducing fog and drizzle chances in
the second half of the work week.

And while some folk aren`t the biggest fans of June Gloom and "No
Sky July", remember this is keeping a fair moisture feed in the
area, and helps keep us out of critical fire danger. The cloud cover
also helps the night shift sleep better during the day, but that`s
more of a personal plus.

&&

.AVIATION...
(12Z TAFS)
Issued at 432 AM PDT Sun Jun 29 2025

Compressed marine layer continues to hug the coastline but
struggling to make gains inland despite hi-res guidance
suggesting otherwise. VFR is expected to prevail through most
of the day and evening for the North Bay, Bay Area and inland
terminals. IFR/LIFR ceilings this morning for KHAF, KSNS with
low marine stratus surrounding KMRY, but remains VFR.

Vicinity of SFO...VFR is expected to prevail through the forecast
period with marine stratus lingering in the vicinity of the
terminals. Guidance has been struggling with the position and
inland extent of the marine layer. IFR ceilings are possible later
tonight but confidence is low attm.

SFO Bridge Approach... Similar to SFO.

Monterey Bay Terminals...LIFR/IFR conditions are expected to
persist through at least the morning hours, with some clearing
expected by early afternoon, before the marine stratus returns
this evening. KMRY is currently surrounded by marine stratus but
continues to be VFR with clearing over the terminal. Approach into
KMRY this morning may be through some low stratus decks despite
being VFR.

&&

.MARINE...
(Today through Friday)
Issued at 306 AM PDT Sun Jun 29 2025

Significant wave heights will continue to gradually subside
through today along with easing winds. Breezy northwesterly winds
will continue over the open waters today while southerly breezes
persist along the coast of Point Reyes. Significant wave heights
begin to build again on Tuesday with strong northwesterly breezes
and moderate to rough seas that will persist into late next week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&

$$

UPDATE.......RWW
SHORT TERM...Murdock
LONG TERM....Murdock
AVIATION...Kennedy
MARINE...Kennedy

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