455
FXUS66 KSGX 102054
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
154 PM PDT Fri Oct 10 2025

.SYNOPSIS...
A low pressure system off the West Coast will continue to draw
moisture from Tropical Storm Priscilla northward into the area
through Saturday morning, with chances for showers and
thunderstorms at times. Cooler with drying and a return of the
marine layer early next week. For Tuesday and Wednesday of next
week, a low pressure system moving southward along the West Coast
will bring a chance of showers along with stronger westerly winds.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

Tonight through tomorrow...

Latest water vapor imagery continues to show the main moisture plume
streaming northward from the area of low pressure associated with
the decaying remnants of Priscilla, remaining confined to the
southeast of the CWA this afternoon. A few showers are beginning to
pop over the Mt Palomar region. There is some upper level difluence
causing this, along with weak instability that has been providing a
few showers over the region since this morning, but coverage has
been very sporadic. This will continue throughout this afternoon
as the low pressure advances slightly northward, with bands
possibly developing over the coastal and inland areas. However,
given the nature of our area being somewhat "dry-slotted" by being
located in between the longwave trough upstream to the northwest,
and the weakening tropical system to the south, and thus will
likely only amount to very sparse development, with come areas
getting in on the precipitation, whilst most other areas remain
dry. As we progress further orographic lifting will help to aid in
the development of a few thunderstorms over the mountains. If
these storms become nearly stationary, or train over the same
area, it could become problematic, as PWATs are still over 100
percent. I have very little confidence of occurrence of this, and
impacts will likely be more sparse and localized. Moreover, the
main source of moisture may remain mostly confined to just the
southeastern portion the San Diego County. Shower/storms that do
develop later this afternoon and into the evening should have a
northeastern movement to them due to mid-level flow being out of
the southwest, so for instance, if a storm does form over Mt. San
Jacinto, it may be impactful for Palm Springs. Again, this will
all depend on where the "splitting" (difluence) of the upper
levels occurs, which will determine where the convection develops.
In terms of tomorrow, most of any remaining shower/storm should
depart the CWA by later this evening, with clearing skies going
into tomorrow morning. There still exists the very slight chance
of a thunderstorm over the mountains during the afternoon hours
tomorrow, although it is more likely that conditions will be dry
for all after early tomorrow morning, and winds will be increasing
out of the west with more influence from the troughing upstream
beginning to take shape.

The rest of the weekend through the end of next week...

Sunday will be slightly warmer with dry and breezy conditions. By
Monday, there will be some increasing clouds as the trough continues
to deepen over the eastern Pacific waters. Deterministic models have
been resolving area of low pressure that deepens during the mid part
of next week, and may bring about a much better chance of
measurable precip, especially for the coastal/inland areas from
late Tuesday through early Wednesday, as well as much colder
temperatures. This will also allow for the first snowfall for some
of the higher terrain, as snow levels drop below 7000 ft by
Tuesday. The longwave trough might still hang around going into
the latter part of next week, and may still continue to influence
the region with more chances of rain and cooler temperatures,
depending on the evolution of the trough (with a possibility of
the upper level closed low associated with it retrograding back
to the west and a secondary low emerging from it, although this is
still quite far out in the forecast to be considered reliable at
this time.

&&

.AVIATION...
102000Z....SCT -SHRA will continue to move northward across the area
today into tonight. Most areas will see SCT-BKN cloud deck near 150K
ft MSL. SHRA/ISO TSRA activity will bring BKN clouds based 8000-
12000 feet MSL at times, best chance across San Diego County and all
mountains/deserts until  10Z Sat. Any TSRA could lower cloud bases to
5000 feet MSL briefly, and could bring gusty winds and reduced vis
in +RA. Decreasing clouds and -SHRA into Saturday morning. Low to
moderate confidence on any BKN cigs based around 1000-2000 feet MSL
developing 09-17Z Saturday near the coast; highest confidence near
VCTY KSAN. Otherwise, drier and clearer on Saturday for the region.

&&

.MARINE...
Northwest wind gusts occasionally exceeding 20 knots around San
Clemente Island during the afternoons and evenings, highest chance
on Saturday. No hazardous marine conditions are expected today
through Monday. Increasing winds expected by Tuesday as another
weather system approaches the area.

&&

.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.

&&

$$

PUBLIC...Stewey
AVIATION/MARINE...APR