051
FXUS66 KMTR 031834 AAA
AFDMTR

Area Forecast Discussion...UPDATED
National Weather Service San Francisco CA
1134 AM PDT Tue Jun 3 2025

...New AVIATION...

.SYNOPSIS...
Issued at 316 AM PDT Tue Jun 3 2025

No major changes to the forecast as temperatures remain near or just
below normal for another day or two and then moderate for the later
portion of the week and weekend. Onshore flow is expected each day,
with portions of the west Delta, within gaps and channels, and

&&

.UPDATE...
Issued at 926 AM PDT Tue Jun 3 2025

We`re keeping an eye on southern Monterey Co as lingering high-based
convection continues to move through SLO Co and is near the CWA
boarder. While there has been some lightning activity in Hanford
and Oxnard`s CWAs, not much has made it to our CWA.

Additional things we`re keeping track of include the atypical
stratus pattern as we switch between a low pressure to high pressure
pattern as well as some haze in the area as smoke from the Canadian
wildfires continues to move into the area.

-Murdock

&&

.SHORT TERM...
(Today and tonight)
Issued at 316 AM PDT Tue Jun 3 2025

Key Messages

-Nighttime and morning stratus, perhaps patchy drizzle along the
coast.
-Near or slightly below normal temperatures.
-Increased breezes across the west Delta/areas of complex terrain

Another interesting night of satellite imagery for us. The cutoff
low we`ve been tracking along our coast this weekend is currently
west of central/southern CA this morning. Fairly dry air is noticed
in the low water vapor channel while there is some moisture and the
mid to upper levels. We can see a few high clouds trying to stream
from the Valley in our south Central Coast counties, otherwise the
main thing we`re watching this morning is the stratus. It has taken
a little longer to fill than expected with the Bay Area counties
starting to see a good push. Here along the Central Coast, it is
taking even longer to return. Expect the stratus deck to increase
over the next few hours, which should leave a good chuck of the
coastal communities and interior valleys cloudy by daybreak. Patchy
drizzle may be possible for coastal communities. Expect conditions to
begin clearing out by mid to late morning, clear skies expected by
the afternoon; however, there could be an exception for communities
along the coast. As we head into the afternoon and evening hours,
onshore winds increase where gusts up to 30 mph are possible for
portions of the west Delta, within gaps and channels, and across
higher terrain.

&&

.LONG TERM...
(Wednesday through Monday)
Issued at 316 AM PDT Tue Jun 3 2025

-Gradual warming trend

The upper low is projected into southern CA late Tuesday night into
Wednesday morning, before becoming more of a long wave later that
day. To our east, surface high pressure builds over the eastern
Pacific which will leave us on the cusp of weak upper level ridging
to near zonal flow. Nonetheless, this will lead to a slight warming
trend for Wed and Thu and likely lead to the marine layer stratus
surging in during the overnight hours. Looking behind Thursday,
ensemble, cluster analysis, and model guidance shows a longwave
trough trying to push back in to southern CA pushing the eastern
Pacific high more towards the PacNW. This guidance also favors the
ridging building into the PacNW and northern CA into the weekend.
This continues to support the gradual warming trend we`ve seen over
last few days.

&&

.AVIATION...
(18Z TAFS)
Issued at 1130 AM PDT Tue Jun 3 2025

VFR anticipated by 20 UTC with a low chance for MVFR cigs
lingering after this time. While the potential for VFR at KHAF is
~20%, trends in satellite support a few hours of VFR. Trends will
be monitored. VFR is anticipated through the entire period at KLVK
and KSJC. Largely diurnal breezes are anticipated, with medium
confidence in elevated winds this afternoon along the west Delta
and SF Bay, where winds may gust to around 25 knots at KAPC and
KOAK. Though KOAK tends to `overachieve` with respect to wind
gusts, probabilities 25+ knot gusts are less than 10%.

There may be just enough influence from a diffuse trough sliding
through the Great Basin to mitigate what would otherwise be a much
more prolonged poor ceiling/visibility event at TAFs on Wednesday
AM. The exception is at KHAF. Local effects at KSTS may still
dominate aviation weather conditions through at least sunrise. As
winds aloft become more northerly in response to the
aforementioned trough, MVFR ceilings/visibility will erode/lift
with VFR anticipated through the remainder of the TAF set. Because
the trough is very subtle in the guidance, there`s low to medium
confidence in the forecast. The current TAF set remains very
optimistic compared to some of the traditional guidance and if the
trough has less in the way of influence, noteworthy alterations
to the forecast will be needed. Otherwise, reductions in slant
visibility due to HZ are anticipated, however, impacts to
horizontal/runway visibility is expected to be limited.

Vicinity of SFO...VFR for a majority of the TAF set. Confidence
in MVFR stratus is low and guidance advertises a 20-30% chance for
cigs around FL015. If an upper trough to the north and east of
the region has less in the way of influence, then there will be an
opportunity for a longer duration ceiling event at SFO on
Wednesday morning. For now, a 2-4 hour window of ceilings around
FL015 has been advertised, though if winds aloft become northerly,
it`s possible that VFR prevails through the entire TAF cycle.
Otherwise, diurnal NW to WNW breezes are anticipated, with an
increase in the gust potential (around 25 knots) near/after 21 UTC
as winds funnel through the San Bruno Gap.

SFO Bridge Approach...HZ may result in slant visibility
reductions and despite the lack of cigs, occasional loss of VAPS
may result if HZ is sufficiently thick/dense.

Monterey Bay Terminals...VFR will prevail through late
afternoon/early evening, with an increased potential for MVFR/IFR
ceilings, especially by 06 UTC. The wind patterns are a little
atypical and this lowers confidence in the exact onset/timing of
ceilings at KMRY and KSNS. The model consensus and time of year,
however, does support a more prolonged periods of reduced
ceilings, especially at KMRY. The current KSNS TAF may be a little
too pessimistic on the back end of stratus and it`s conceivable
that VFR returns prior to 17 UTC Wednesday if a Monterey Bay eddy
develops and disrupts stratus intrusion into the Salinas Valley.

&&

.MARINE...
(Today through Sunday)
Issued at 926 AM PDT Tue Jun 3 2025

Strong high pressure to the north and low pressure inland will
support near gale force wind gusts. The most likely areas for gale
force winds and hazardous seas will be over the outer waters
north of Point Reyes with strong gale force gusts. South of
Pigeon Point winds will be weaker and westerly to southerly. The
Delta breeze will also increase later this afternoon, resulting
in hazardous boating conditions for portions of the San Pablo Bay
and west Delta regions.

&&

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

     Gale Warning until 9 PM PDT Wednesday for Pt Arena to Pt Reyes
     10-60 NM.

&&

$$

SHORT TERM...KR
LONG TERM....KR
AVIATION...Bain
MARINE...Bain

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NWS MTR Office Area Forecast Discussion