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758
FXUS66 KSGX 230421
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
921 PM PDT Sun Jun 22 2025

.SYNOPSIS...
Minor day-to-day variations in temperatures through Tuesday. A
gradual warming trend is expected for the middle to end of the
week. The marine layer will bring night and morning low clouds to
coastal areas through the week. Low clouds are expected to reach
into the valleys at times, most likely during the first half of
the week.

&&

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

This evening...The marine layer remains about 2500 ft deep with a
weak inversion but skies are clear except for a patch of low
clouds off the coast of San Diego County. High-resolution models
show about a 40-60 percent chance for low clouds in the coastal
areas and western portions of the San Diego County valleys between
about midnight and 10 am Monday.

From previous discussion...
A long wave troughing pattern will remain over the Western United
States early this week. That will keep high temperatures 5 to 10
degrees below average through Tuesday. Marine layer low clouds and
fog are expected each night and morning and will reach into the
western portions of the valleys.

On Wednesday the upper level troughing will shift east, but
cyclonic flow aloft will remain over the region into Friday.
Ensembles are in generally good agreement with upper level high
pressure beginning to build in from the southeast into next
weekend but there remains uncertainty in the placement of the
ridge. Only about 25 percent of solutions have the ridge axis over
the West Coast, which would result in the hottest conditions.
Regardless, a gradual warming can be expected for the middle to
end of the week with lingering uncertainty in just how hot it will
get. Friday through Sunday, the difference between the coolest
high temperature solution and the warmest is about 10 degrees for
the valleys and mountains. NBM chances of the deserts reaching or
exceeding 110 degrees is around 15 percent Saturday and closer to
30 percent Sunday. The building high pressure aloft should keep
the marine layer shallower and more confined to coastal areas.

&&

.AVIATION...
220300....Coast/Valleys/Coastal Mountain Slopes...VFR conditions
throughout the region this evening. Low clouds with bases
1500-2500 ft MSL redevelop along the coastline 06-09z and spread
into the valleys of San Diego/Orange Counties 09-12z. Clouds may
briefly spill into the far western and far southern portions of
the IE. Low clouds clear to the coast 15-17z Monday morning. 30%
chance that BKN CIGs linger through the afternoon at the coast.
Low clouds with similar bases begin to push inland again around
03-06z Tuesday.

.Mountains/Deserts...Clear skies and largely unrestricted VIS
through Monday evening. Wind gusts 25-35 kts Monday afternoon and
evening with isolated gusts to 45 kts through mountain passes.

&&

.MARINE...
No hazardous marine conditions are expected through Thursday evening.

&&

.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...PG
AVIATION/MARINE...KW