Coachella, California Weather Forecast Discussion

903
FXUS66 KSGX 071547
AFDSGX
Area Forecast Discussion
National Weather Service San Diego CA
847 AM PDT Sun Sep 7 2025
.SYNOPSIS...
Mostly clear skies with near average temperatures will occur across
the region this weekend. Monsoonal moisture continues to lower, so
slight chances of weak showers and thunderstorms may occur over the
mountains this weekend as well. Drier weather is expected across all
areas next week. A noticeable cooling trend is expected by the
middle of the week with highs from 5 to 15 degrees below average
with breezier conditions across the deserts and adjacent mountains.
The marine layer will also be deeper next week, contributing to
clouds and fog west of the mountains each night and morning.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
.Morning Update...
San Diego`s morning sounding shows good moisture above the
inversion and below 700 mb`s, elevated CAPE extending to the
tropopause and as PWAT values above an inch; the slight chance for
isolated showers and storms over the mountains this afternoon is
still on track. Patchy mid-level clouds are currently building
over desert areas; cumulus clouds to develop in the next few hours
over the mountains with precipitation possible after 1 PM and
wrapping up by 6 PM. As the low and mid-level winds turn westerly
tonight, monsoonal moisture will be pushed out of the region and
shower chances will end.
.Previous Discussion (315 AM PDT Sunday)...
Today through Monday:
The upper level ridge centered over the Desert Southwest strengthens
some today, allowing high temperatures today to be a touch warmer
compared to Saturday. Enough monsoonal moisture remains in place
that a few storms could develop over the mountains again this
afternoon (~20% chance), primarily across the San Diego/Riverside
County mountains. High resolution guidance is indicating that the
strongest storms this afternoon could produce rainfall rates near
0.3-0.4" per hour. A few storms could drift eastward from the
mountains into the adjacent deserts. After today, mid/upper level
flow turns northwesterly ahead of an incoming trough, pushing
monsoonal moisture back east, bringing an end to the shower/storm
chances. High temperatures Monday afternoon look to be a few
degrees cooler than Sunday as heights fall with the ridge
weakening and beginning to give way to the incoming trough.
Tuesday through the end of the Week:
Ensemble guidance is quite consistent with a slow-moving longwave
trough moving into northern California and Oregon Monday into
Tuesday and is largely stationary through Thursday/Friday with
shortwaves rounding the parent trough. This pattern will bring
cooler, cloudier, and windier conditions for mid-late week. 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. While the marine layer today/tomorrow
(Sun/Mon) will be fairly patchy and shallow, it will deepen
considerably by Wednesday, 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...
071515Z...Coast... Mostly clear skies through the evening hours.
Moderate confidence in BKN cigs 700-900 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 20Z Sun to 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.
&&
.MARINE...
No hazardous marine conditions are expected through Wednesday.
&&
.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/Munyan
AVIATION/MARINE...APR

NWS SGX Office Area Forecast Discussion