288
FXUS66 KSGX 261620
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
920 AM PDT Tue Aug 26 2025

.SYNOPSIS...
There will be another round of afternoon and early evening
thunderstorms today, mainly for the mountains and deserts with
strong gusty winds and locally heavy rainfall. There will be
decreasing moisture and thunderstorms chances for Wednesday. Mid
and high level moisture from the remnants of Tropical Storm
Juliette could bring some scattered showers and isolated
thunderstorms on Thursday. Then gradual warming and drying for
Friday through the weekend with a slight chance of showers and
thunderstorms for the San Bernardino Mountains each afternoon.

&&

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

.Morning Update...

Low clouds continue to clear out near the coast, with most low
clouds clearing by later this morning. The morning`s sounding
shows PWAT values again near 1.5" like yesterday, but areas above
500mb are much drier, which will limit storm growth this
afternoon. Hi-res models are in a bit of a disagreement with this
latest run this morning as local WRF model shows less coverage in
storms over the mountains and deserts, while the HRRR and HREF models
show more numerous shower activity. Seeing that moisture remains
in place with sufficient instability, storms will again have the
potential to produce hourly rain rates over one half inch. Storm
chances will remain elevated across these regions this afternoon,
with lowering chances by Wednesday, more focused on the mountains.
Highs will be near average west of the mountains to slightly
below normal across the mountains and deserts over the next few
days. A lowering trend in humidity will also be noted across the
region over the next few days area wide as well.

.Previous Discussion (351 AM Tuesday)...

.SHORT TERM (Today through Thursday)...
There will be decreasing monsoonal moisture into Wednesday. There will
be another round of afternoon and early evening thunderstorms
today, mainly for the mountains and deserts, with strong gusty
winds and locally heavy rainfall. There will be decreasing
thunderstorms coverage on Wednesday afternoon with the drying.

For Thursday, mid and high level moisture from the remnants of
Tropical Storm Juliette could bring some scattered showers and
isolated thunderstorms, mainly across about the southeastern half
of southern California.

&&

.LONG TERM (Friday through Monday)...
There will be gradual warming and drying for Friday through Sunday
with a slight chance of afternoon showers and thunderstorms for
the San Bernardino Mountains.

With the warming, high temperatures on Sunday will mostly be
within a few degrees of average. High temperatures on Sunday will
range from the mid 70s to lower 80s near the coast to the 90s to
around 100 for the Inland Empire with 106 to 110 for the lower
deserts.

The marine layer will be near 1200 to 1500 feet deep with night
and morning low clouds over the coastal waters spreading into
coastal areas each night.

&&

.AVIATION... 261500Z...Coast/Western Valleys...Low clouds based 1000-
1300 ft MSL will continue to scatter out to the coast through 17z.
Low clouds to tentatively return late tonight into Wednesday 06-10Z,
with bases/vis a little lower and coverage more confined to the
coast.

Mountains/Deserts...Isolated +SHRA/TSRA 18-01Z with CB bases around
10 kft, mostly confined to the mountains. Gusty and erratic winds of
35 kts or greater, 1-3 SM vis in +RA, small hail, and lightning are
possible. 40-50% chance of TSRA VCNTY KPSP and KTRM until 01z
Wednesday.

&&

.MARINE...
No hazardous marine conditions are expected through Saturday.

&&

.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...APR/17
AVIATION/MARINE...Westerink

NWS Tucson (SGX) Office