550
FXUS66 KSGX 210931
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
231 AM PDT Sat Jun 21 2025

.SYNOPSIS...
Cooler with extensive marine layer low clouds today. Gusty
westerly winds developing over the mountains and into the deserts
this afternoon and evening. Below average temperatures will
continue early in the week, with a gradual warming for the middle
to end of the week.

&&

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

Marine layer low clouds have filled in across the coastal basin
this morning and are even making it into the Cajon Pass. Low
clouds will clear inland by late morning, but coastal areas will
remain at least partly cloudy through the day. Elsewhere skies
remain clear. West winds have weakened slightly this morning, but
will strengthen again this afternoon and evening with wind gusts
around 30-45 mph across the desert mountain slopes and into the
deserts, with isolated gusts up to 60 mph through the San
Gorgonio Pass. Otherwise cooler today as an upper level trough
moves through with highs around 10-15 degrees below normal inland.

A long wave trough remains across the western US through Tuesday,
maintaining below normal temperatures. High temps begin to
increase Sunday as onshore flow weakens, followed by minimal day-
to-day variations through Tuesday with highs around 5-10 degrees
below normal each day. Marine layer low clouds will spread into
the valleys each night and morning.

The upper level jet lifts north with low amplitude troughing near
the Pac NW for the latter half of the week. While there are some
differences in the depth and placement of this trough as we head
into the weekend, the general consensus is for gradual warming and
a shallower marine layer with less extensive night and morning low
clouds and fog Wednesday into next Weekend with highs near
seasonal normals.

&&

.AVIATION...
210930Z....Coast/Valleys...Low clouds have filled in through the
Inland Empire and the entire coastal basin this morning. Aided by a
coastal eddy spinning over the California Bight, bases are sitting
near 2500ft MSL with a patchy secondary layer closer to 1500-1800ft
MSL along the coasts. This lower layer is largely FEW-SCT but may
bring an occasional CIG below 2000ft to the coasts. VIS 1-5SM where
clouds and terrain intersect, obscuring higher terrain. Inland areas
clearing by 15-16z with the coasts clearing by 17-18z. Clouds likely
lingering offshore through the afternoon, but will push back ashore
into coastal San Diego County as early as 00z Sunday. Clouds will
likely spread into Orange County and through the Inland Empire as
seen this morning, though there is less confidence in full coverage
of clouds that far north compared to this morning. Regardless, bases
will likely be similar to this morning, around 2000-2500ft MSL.

Mountains/Deserts...Clear skies and unrestricted VIS through
early Sunday morning. After largely taking a break overnight and
this morning, westerly winds with gusts 30-50 knots pick back up
by 18-21z this afternoon for mountain passes and locally into
deserts. These gusts are likely to produce pockets of
up/downdrafts in lee of mountains/mountain passes in addition to
isold BLDU in the desert with VIS 3-5SM at times. Winds gradually
weaken tonight into Sunday morning.

&&

.MARINE...
Aside from northwesterly wind gusts near 20 kts in the vicinity of
San Clemente Island this afternoon, 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...Wind Advisory until 11 PM PDT this evening for Apple and Lucerne
     Valleys-San Diego County Deserts-San Gorgonio Pass near
     Banning.

PZ...None.

&&

$$

PUBLIC...SS
AVIATION/MARINE...Munyan