Carlsbad, California Weather Forecast Discussion

044
FXUS66 KSGX 100429
AFDSGX
Area Forecast Discussion
National Weather Service San Diego CA
929 PM PDT Tue Sep 9 2025
.SYNOPSIS...
A large low pressure system moving slowly into the western states
will bring stronger onshore flow, spreading cooling inland and
deepening the marine layer to around 3000 feet with night and
morning coastal low clouds covering most of the coast and valleys
for early tomorrow morning and early Thursday morning, with some
areas of light drizzle possible. Southwest winds gusting 30 to 40
mph for the deserts and the desert slopes of the mountains will
steadily weaken. This will be followed by warming for Friday and
Saturday and additional warming for early next week with the
marine layer becoming shallower.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
This evening...The marine layer is about 2000 ft deep with a
fairly weak inversion. Cooling is evident both above and below the
inversion. Low clouds are increasing in coverage and spreading
inland. Low clouds - with fog on higher elevations - will likely
reach the coastal mtn slopes by sunrise on Wednesday.
From previous discussion...
A large low pressure system over the eastern Pacific is
continuing to slowly propagate towards the region and will bring
cooler temperatures and more of a persistent onshore flow to
SoCal, with the marine layer becoming more predominant and
extending further inland than in recent days. There will also be
gusty afternoon winds for the higher elevations of the mountains
and deserts, especially for the ridgetops and through the
mountains gaps and passes. There could be occasionally gusts up to
55 mph at times within the Gorgonio Pass this evening. There
could also be some areas of blowing dust, and this will continue
through this evening, and then winds will begin to decouple and
subside overnight. They will strengthen again tomorrow afternoon
for the same areas, although they will likely remain below the
threshold for a majority of the period, and therefore Wind
Advisories will not be needed for tomorrow. Temperatures will also
be notably lower tomorrow, and the coolest day of the week. There
will be only a slight and very gradual warmup going into the
weekend coming up as the trough begins to fill and retreats a
little more to the north. The marine layer will also thicken up a
little more tonight with increasing heights, and this may allow
for there to be some areas of drizzle, especially for the
foothills during the early morning hours.
Early through mid part of next week...
Both deterministic models and ensembles alike are displaying a
return of ridging early next week, which will allow for a jump in
high temperatures for next Monday, and then even further warming
going into the middle of next week. The marine layer will also begin
to thin and lower and high pressure builds in stronger going into
the middle of next week. Conditions also will continue to remain dry
throughout this period in the forecast.
&&
.AVIATION...
100315Z...Coast/Valleys...Low clouds based 1700-2000 ft MSL have
moved into coastal San Diego. Clouds to move in Orange County
through 07Z and into the eastern valleys/Inland Empire 06-10Z. Bases
rise slightly overnight to 2000-2500 ft. Reduced vis 2-5 SM for high
terrain in inland valleys, and is also possible in spotty light
drizzle. Clouds scatter out of inland areas 15-17Z, then coastal
areas 17-21Z. There is a 30% chance that sites along the immediate
coast could remain BKN through the afternoon. Clouds with similar
bases move inland again after 11/00Z, to similar inland extent.
Mountains/Deserts...Areas of west to southwest gusts 30-40 mph for
ridgetops and desert slopes, locally up to 50 mph in mountain
passes, through about 11Z. Mostly clear with VFR conditions tonight
and Wed. Winds strengthen again after 19Z for same areas, though
weaker than today.
&&
.MARINE...
Occasional northwest wind gusts exceeding 20 kt in vicinity of San
Clemente Island Wednesday afternoon and evening. Otherwise, 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...Wind Advisory until 1 AM PDT Wednesday for Apple and Lucerne
     Valleys-Riverside County Mountains-San Bernardino County
     Mountains-San Diego County Deserts-San Diego County
     Mountains-San Gorgonio Pass near Banning.
PZ...None.
&&
$$
PUBLIC...PG
AVIATION/MARINE...CSP

NWS SGX Office Area Forecast Discussion