081
FXUS66 KMTR 302335
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
435 PM PDT Mon Jun 30 2025

...New AVIATION, MARINE...

.SYNOPSIS...

&&

.SHORT TERM...
(This evening through Tuesday)
Issued at 120 PM PDT Mon Jun 30 2025

Skies are sunny across the district with a 1200 foot marine layer
along the immediate coast. Convection noted this morning remains
offshore, well west of the Sonoma coast and continues to move away
from our coastal waters. Well to our north up in Trinity county
some of the first convection over land associated with the upper
low west of Big Sur is starting to initiate and that is being
captured fairly well by the CAM models. In terms of sensible
weather for the Bay Area its a pretty seasonal afternoon with
temps 60s coast, 70s bayside, 80s inland and 90s for the interior
hot spots of the Central Coast. For tonight the well defined
marine layer along the coast will spread into the coastal valleys
once again. With a depth under 1500 feet it shouldn`t spread too
far inland. Similar to the last few evenings some coastal drizzle
and fog is likely during the evening and overnight hours.

For Tuesday the upper low wont move too much but inch closer the
coast. Instability rotating around the low will remain focused
over the Sierra and mountains of northern California, keeping
the best thunderstorm chances over the higher terrain (where Red
Flag Warnings are currently in effect) and likely avoiding the
Bay Area through at least Tuesday afternoon. Thus expect another
sunny and seasonable day for the first of July across the Bay Area
with no unseasonably hot temps forecast.

&&

.LONG TERM...
(Tuesday night through next Sunday)
Issued at 120 PM PDT Mon Jun 30 2025

About a 10 percent chance that a stray thunderstorm or two could
sneak into extreme northern Sonoma or Napa counties Tuesday
evening per some of the latest HRRR/HREF runs while even the gfs
shows some mucape bullseyes over northern Napa county around 03z
Weds. All that being said the most likely scenario is any
convection stays north and east of the Bay Area. However, any
slight bobble in the location of the upper low could send a vort
lobe over mid-level instability further south than currently
expected.

On Weds the upper low will finally eject and the main flow will
turn more westerly, ending the t-storm threat and associated
instability. By Weds afternoon weak shortwave ridge will try and
build over the Central Coast.

Yet another late season trough is forecast to approach the region
by Thursday. This one will be more progressive (versus cut-off)
with slightly cooler air aloft. Main concern would be slightly
stronger westerly winds Thursday afternoon and evening to coincide
with any pre 4th of July activities. Temperatures will remain near
or slightly below normal and the marine layer could deepen to 3000
feet or so later Thursday into Friday.

Trough axis passes overhead on 4th of July meaning no unseasonably
hot temps to contend with mainly 70s and 80s inland. Quiet and
uneventful weather forecast through the weekend with a general
trough in place at least through July 7th. By around July 8-10th
some hints that the Four-Corners ridge could start to expand and
build some heat farther northward but confidence remains low to
medium given the resiliency of the West Coast trough the last 4-5
weeks.

&&

.AVIATION...
(00Z TAFS)
Issued at 419 PM PDT Mon Jun 30 2025

Expect VFR conditions for the remainder of the afternoon and early
evening with the exception of HAF. Breezy diurnal winds will ease
after sunset. Onshore flow increases toward the end of the TAF
period Tuesday evening, when Bay Area winds will increase to
around 15 knots.

Vicinity of SFO...VFR for the remainder of the afternoon and
evening with gusty winds up to 25 knots, easing around sunset.
Marine layer has been struggling to reach SFO and OAK, so
confidence is low that IFR/LIFR cigs will develop early Tuesday
morning but it is possible. Breezy onshore flow will lift winds to
15 knots or higher toward the end of the TAF period.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR conditions are expected to prevail
for the remainder of the afternoon with IFR/LIFR cigs expected to
develop in the early evening hours and persist through the
overnight hours into the early afternoon on Tuesday.

&&

.MARINE...
(Tonight through next Saturday)
Issued at 419 PM PDT Mon Jun 30 2025

Locally breezy to gusty conditions are possible in the  afternoon
and evening across the San Pablo Bay and Suisun Bay with a Small
Craft Advisory in effect. Significant wave heights will  build
early Tuesday morning as northwest winds strengthen and gradually
spread across the outer waters through the rest of the week. Winds
will be strongest across the northernmost outer  waters with winds
strengthening to near gale force by midweek.  Winds and seas will
then remain elevated across the coastal waters through the end of
this week and into the next.

&&

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

     Small Craft Advisory from 3 PM Tuesday to 3 AM PDT Wednesday for
     Pt Arena to Pt Reyes 10-60 NM.

&&

$$

SHORT TERM...RW
LONG TERM....RW
AVIATION...JM
MARINE...Kennedy

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