947
FXUS66 KSGX 272030
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
130 PM PDT Wed Aug 27 2025

.SYNOPSIS...
Isolated showers and storms will occur over the mountains into the
deserts through early evening. An abundance of clouds and high
level moisture from Tropical Storm Juliette to our south will
bring scattered showers later tonight through Thursday. Warmer and
drier weather will occur by Friday into the weekend with minimal
chances for storm activity. Monsoonal moisture will slowly return
early next week with a slight chance of afternoon and early
evening thunderstorms for the mountains and deserts.

&&

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

Cumulus clouds continue to build off of the mountains as light
showers are noted early this afternoon. Areas of showers and
storms will continue through the early evening. Tropical Storm
Juliette continues to weaken and move northward, moving parallel
to the Baja coast. High clouds from this are already moving into
SD County this afternoon. Clouds will thicken this evening, with a
cloudy and cooler day by Thursday. Highs will stay in the 80s/90s
across the deserts, with 70s/80s west of the mountains. The
atmospheric profile will be plenty moist enough for areas of virga
and light showers to fall across much of the area, highest
chances across SD County and Riverside County. There is a slight
chance of thunder with this system moving through. Otherwise,
model guidance shows rainfall mostly under one quarter of an inch
for most areas with mountains receiving up to a half inch; a
beneficial sight for August!

Skies will clear out by Thursday night. Friday will see a drying
trend, which will limit the storm chance across the mountains to
near 10 percent. High pressure over northern Mexico will grow and
expand this weekend. This will bring drier, less humid air to the
area with warmer temperatures. This will bring temperatures closer
to near average with highs near 110 across the deserts and 90s
across inland valleys west of the mountains. Cumulus clouds may
build over some of the mountains each afternoon, but the threat
for thunderstorms will be minimal.

The area of high pressure will amplify further over the desert
southwest by next Monday and Tuesday, providing a path for
increased monsoonal moisture to return to our area. This will lead
to increased chances for shower and thunderstorms across the
mountains and deserts with mostly clear skies and near average
temperatures elsewhere. Ensemble cluster models start to have
larger solution spread on the high remaining in place into the
middle of the week, while some others show a weaker trough forming
off the coast, which would bring slightly cooler and drier
weather to our region.

&&

.AVIATION...
272000Z...Coast...VFR this afternoon with only very patchy low
clouds based 800-1000 ft at the immediate coast overnight tonight.
Remnants from Tropical Storm Juliette will slide into San Diego
and Riverside Counties from the south overnight, bringing areas of
-RA/RA from 11-20z Thu. Mostly high cloud bases associated with
 this moisture, keeping conditions mostly VFR.

Mountains/Deserts...Isolated SHRA/TSRA through 01Z this afternoon.
CB bases around 10000 feet MSL, mostly confined to the mountains
with lower chances in the low desert and eastern high desert. TSRA
could produce gusty and erratic winds of 30 kts, periods of lower
vis 2- 5SM in +RA, and lightning. Overnight, occasional -RA/RA in
the mountains and deserts after 09z Thu associated with tropical
storm moisture.

Regionwide...SCT clouds at or above 12000 feet MSL from the south
are entering the region. BKN-OVC tonight through afternoon Thu.

&&

.MARINE...
There is a slight chance of thunderstorms Thursday. Any thunderstorm
could produce gusty, erratic winds leading to locally rough seas,
along with lightning and hail. Otherwise, no hazardous marine
conditions are expected through Sunday.


&&

.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
AVIATION/MARINE...Westerink