643
FXUS66 KSGX 081014
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
314 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...

.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...
080930Z....Coasts/Valleys...Low clouds will continue to gather
across all coastal areas and some of the valleys through 14Z. Bases
will be 1000-1500 feet MSL with tops to 1900 feet. Vis reduced 0-5SM
inland. Scatter out 16-19Z. Areas of low clouds with bases around
1500 feet MSL will gradually develop after 03Z into Thursday, but
with less uniform coverage and less inland extent.

Mountains/Deserts...Mostly clear and VFR conditions today and
tonight.

&&

.MARINE...
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.

&&

$$

PUBLIC...17
AVIATION/MARINE/BEACHES...MM