972
FXUS66 KSGX 200922
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
222 AM PDT Fri Jun 20 2025

.SYNOPSIS...
Cooler through Saturday with gusty west winds in the mountains
and deserts, along with a deep marine layer accompanied by
extensive night and morning low clouds west of the mountains.
Slightly warmer Sunday through Tuesday with less extensive marine
layer clouds, followed by more significant warming for the latter
half of the week.

&&

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

Marine layer low clouds have spread into parts of the valleys this
morning, slowly working their way into the far western portion of
the Inland Empire. Low clouds will clear to the coast by late
morning, though the beaches may remain cloudy through much of the
afternoon. Elsewhere skies are and will remain clear.

An upper level low off the coast of British Columbia will slowly
drop southeasterly into Idaho through Saturday with the long wave
trough axis digging into So Cal. This will bring cooler weather
through Saturday, when highs will be as much as 10-15 degrees
below normal inland, and around 3-5 degrees below normal along the
coast. This trough will also generate gusty west winds in the
mountains and deserts, strongest through the San Gorgonio Pass
where gusts to 55-60 mph are possible this evening and again
Saturday evening. Remaining portions of the desert mountain slopes
and deserts will have gusts around 25-40 mph. The marine layer
deepens slightly, though inland extent of the low clouds will
depend on the position of a robust coastal eddy that develops in
response to strong NW winds coming around Point Conception.

Weak troughing remains over the Western US Sunday and Monday as a
secondary low develops in the mean trough and digs towards So Cal,
progressing westward on Tuesday. This will maintain cooler weather
with highs around 5-10 degrees below normal each day and marine
layer low clouds spreading into the western valleys each night.
The jet stream/upper level troughing shifts north during the
latter half of the week for gradual warming and less extensive
night and morning low clouds.

&&

.AVIATION...
200915Z....Coast/Valleys...Marine layer clouds have filled in
uniformly through about 20-25 miles inland this morning, and will
continue to filter into portions of the Inland Empire through 09-
12z. CIGs have already reached KONT and there is a 75% chance they
reach KSBD by 14z. Bases are sitting around 1300-1500 ft MSL with
VIS restrictions limited to eastern valleys and where clouds
intersect higher terrain. Clouds retreat back to the coasts by 17-
18z, and while a few clouds may linger at the beaches into the
afternoon, VFR will prevail through the remainder of the day. Low
clouds fill back in and push ashore this evening, as early as 00z
Saturday for portions of San Diego County, before eventually
spreading inland and northward through Orange County and the Inland
Empire through 06-12z. Bases and VIS restrictions similar to this
morning, closer to 1400-1700ft MSL.

.Mountains/Deserts...Clear skies and unrestricted VIS through
early Saturday. Westerly winds pick up by 18-21z this afternoon with
gusts 25-40 knots through mountain passes and locally into deserts.
These winds are likely to produce pockets of up/downdrafts in lee of
mountains/mountain passes in addition to areas of BLDU with VIS
below 3SM possible at times. Strong winds become more restricted to
the mountains/mountain passes after 06z Saturday.

&&

.MARINE...
Northwest wind gusts 20-25 knots near San Clemente Island this
afternoon and evening. Otherwise, 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 from 11 AM this morning to 11 PM PDT Saturday for
     San Gorgonio Pass near Banning.

PZ...None.

&&

$$

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