789
FXUS66 KSGX 081637
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
937 AM PDT Wed Oct 8 2025

.SYNOPSIS...
A low pressure system off the West Coast will draw tropical
moisture northward into the area for Thursday into Friday night
with increasing chances for showers and a chance for thunderstorms.
Cooler with drying for Saturday through Monday. For Tuesday and
Wednesday of next week, a low pressure system moving to near the
West Coast will bring a chance of showers.

&&

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

Update: The latest track of Priscilla remains similar to previous
models, which shows that a majority of the moisture streaming up
over the area from tomorrow through Friday to be located over San
Diego County. For this reason, the mountains of San Diego will
likely have the best chance of thunderstorms developing overhead
during the afternoon. Otherwise, it will just likely be on and off
showers falling from a relatively high based mid-level scattered
to broken cloud deck. PWAT values are still pushing 200, so if a
storm does develop, it could put down a heavy amount of rain in a
short period of time, of possibly a half an inch or greater per
hour. Having said this, it doesn`t appear that the system is well
organized, which could indicate that it is undergoing much
weakening and may not have as much moisture associated with it as
the remnants make their way over the region. Given the higher
PWATs, if there is a stronger shower or possible storm the
develops and remains nearly stationary, it could cause some flash
flooding problems.

(Previous discussion submitted at 314 AM):

.SHORT TERM (Today through Friday)...
The marine inversion has slowly strengthened and decreased
slightly in depth over the past 48 hours with coastal low clouds
not spreading as far inland into the San Diego County valleys as
the past two mornings. Not much change in high temperatures is
expected for today with high temperatures a few degrees below
average for the coast into portions of the valleys and a few
degrees above average for the mountains and high desert. High
temperatures for today will range from around 70 near the coast to
the 80s for the Inland Empire with the mid to upper 90s for the
lower deserts.

For Thursday into Friday night, a large low pressure system
centered off the West Coast will draw moisture from the remnants
of weakening Hurricane Priscilla northward into the area,
increasing chances for showers and thunderstorms. The greater
chances for heavier rainfall are from the mountains of San
Bernardino, Riverside, and San Diego Counties eastward across the
deserts into Arizona with decreasing chances toward the west.

Higher-resolution model guidance shows bands of showers with a
slight chance of thunderstorms moving northwestward across the
area on Thursday morning with additional chances for showers and
thunderstorms during the afternoon more focused over the mountains
eastward across the deserts. Chances for showers and thunderstorms
will continue at times through Friday into Friday evening. NBM
chances for one inch or more of rainfall is around 5 percent for
the mountains. However, the HRRR does show the potential for
6-hourly rainfall to around 1.5 inch for portions of the mountains
and deserts for Thursday afternoon.

High temperatures for the mountains and deserts will be a few
degrees cooler for Thursday and again for Friday. With the
influx of tropical moisture and increase in clouds, Thursday night
will be warmer with low temperatures for early Friday as much as
15 to 20 degrees above average for the mountains and deserts of
San Diego County.

&&

.LONG TERM (Saturday through Tuesday)...
There will be drying and cooler days for the weekend through
Monday with high temperatures on Monday as much as 12 to 18
degrees below average for the higher elevations of the mountains.
High temperatures on Monday will range from around 70 near the
coast to the 70s for the Inland Empire with the mid 80s for the
lower deserts.

For Tuesday and Wednesday, another low pressure system nearing
the West Coast may spread showers southward into southwestern
California. Cluster analysis shows the clusters with the
relatively wetter solutions are those with the low pressure
system slightly stronger and centered slightly farther to the
west. NBM chances for measurable rainfall for Tuesday morning
through Wednesday night is generally 20 to 30 percent for the
coast to the mountains with chances for one inch or more of
rainfall as much as 5 to 10 percent for portions of the mountains.

&&

.AVIATION...
081530Z....Coasts/Valleys...Low clouds based 1000-1800 ft MSL
covering most of San Diego/Orange County as well as parts of the
Inland Empire. Vis reductions (1-4SM) for elevated inland valleys
including parts of the IE with areas FG before 17Z. Scattering to
the coast 17-19Z with 30% chance BKN clouds at San Diego County
coastline through the afternoon. Areas of low clouds with bases
around 1200-1800 feet MSL will gradually spread inland after 01Z
into Thursday, but with less uniform coverage and mostly confined to
San Diego County. Low clouds scattering out again by 15-17Z Thu.

Mountains/Deserts...Mostly clear and VFR conditions through tomorrow
morning. High clouds moving in after 12Z Thu.

&&

.MARINE...
Northwest wind gusts around 20 kt near San Clemente Island Thursday
and Friday afternoons and evenings. There is a slight chance of
thunderstorms Thursday through Friday. Lightning, erratic winds,
choppy seas, and/or reduced visibility in heavy rain likely in
vicinity of any thunderstorms.

&&

.BEACHES...
There is a 5-15% chance of thunderstorms producing lightning
Thursday through Friday.

&&

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

&&

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

&&

$$

UPDATE...Stewey
PUBLIC...17
AVIATION/MARINE/BEACHES...KW