Murrieta, California Weather Forecast Discussion

943
FXUS66 KSGX 072051
AFDSGX
Area Forecast Discussion
National Weather Service San Diego CA
151 PM PDT Sun Sep 7 2025
.SYNOPSIS...
Slight chance for mountain and desert slope showers and
thunderstorms this afternoon. Otherwise, mostly clear skies across
the region. A pattern shift is set to occur Monday through all of
next week with an upper-level trough developing in the NE Pacific
and stalling out over California mid-week, bringing breezy winds,
significantly below average temperatures and a deeper marine
layer.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
THIS AFTERNOON...Deep cumulus clouds have developed over the
mountains with the slight chance (15-20%) they eventually develop
into showers or an isolated thunderstorm later this afternoon with
rain rates mostly likely below 0.50"/hr. Riverside/San Diego
County mountains and adjacent desert slopes have the greatest
chance for precipitation, through 6 PM this evening.
THIS WEEK AND BEYOND...
The pattern that has allowed for southerly moisture advection and
above average temperatures will be pushed away by a digging trough
off the coast of Oregon. This upper level low will slowly move
south into California, giving the trough axis time to spin up
some weak dry cold fronts, yielding brief periods of elevated
wind across the region from Tuesday through Thursday.
High temperatures are expected to be 10-15 degrees below normal
for Tuesday through Friday with areas near 20 degrees below normal
for early September on Wed/Thurs. From tonight through Wednesday,
the marine layer will deepen considerably, likely extending well
inland each morning. While unseasonably cool, the most notable
impact from this pattern will be the windy conditions, especially
for the mountains/mountain passes and high deserts. Westerly wind
gusts near 25-35 mph expected for most of the deserts/desert
slopes while vulnerable passes like San Gorgonio Pass could see
gusts closer to 45-55 mph. Moving into the late-week, ensemble
guidance suggests the tough will finally weaken and lift north,
moderating afternoon wind gusts and bringing temperatures closer
to normal.
&&
.AVIATION...
072000Z...Coast... Mostly clear skies through the evening hours.
Moderate confidence in BKN cigs 400-900 ft MSL at KSAN/KCRQ 11-15Z
Monday. Vis restrictions 2-5 SM possible again for coastal highlands
during this time period. Mostly clear skies prevailing much of
Monday.
Valleys/Mountains/Deserts...Low chances for ISO SHRA and possibly a
thunderstorm until 01Z Mon for mountains of San Diego and Riverside
counties. CB bases around 10K ft and any TSRA tops to 35K ft. Dry
weather prevailing Monday onward.
&&
.MARINE...
Northwest winds gusting to 20 kts near San Clemente Island in the
afternoon and evening hours on Monday and Tuesday. Otherwise, no
hazardous marine conditions are expected through Thursday.
&&
.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...Westerink
AVIATION/MARINE...APR

NWS SGX Office Area Forecast Discussion