463
FXUS66 KSGX 152052
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
150 PM PDT Wed May 15 2024

.SYNOPSIS...
An upper level disturbance may trigger a few showers over the San
Bernardino and Riverside County Mountains this evening. Dry weather
is forecast Thursday through Sunday. Night and morning low clouds
west of the mountains will clear to near the coast each afternoon.

&&

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

Low topped cumulus formed over the high deserts and the San
Bernardino/Riverside County mountains this afternoon. Mid-level
moisture advection from the northeast increases mountain PWATs to
0.60" this evening for small chances of showers. The best chances
for showers and thunderstorms will be over northern AZ, closer to
the shortwave moving south across Utah, but weak waves in the
northeast flow across SoCal coupled with orographics may trigger a
few showers over the San Bernardino and Riverside County mountains
through this evening. CAPE values peak between 200-500 J/kg, high
enough for an isolated thunderstorm.

West of the mountains the marine layer was having a hard time
clearing from the coastal zones which likely remain mostly cloudy
through the evening. A deep marine again tonight will produce patchy
drizzle Thursday morning, and the deep marine layer will have a hard
time clearing from the coastal zones tomorrow afternoon.

Valley, mountain and desert highs will be a few degrees warmer on
Thursday and Friday as the upper low moves east and weak ridging
builds over the Southwest.

Over the weekend the night and morning low clouds will once again
extend into the valleys each morning with slow clearing to near the
coast in the afternoon. A trough deepening off the coast of Southern
California will bring a few degrees of cooling Sunday, and even
greater cooling and a deeper marine layer Monday.

&&

.AVIATION...
152100Z...Coast/Valleys...BKN/OVC low clouds with layered cloud
bases 1500-3000 ft MSL will continue near the coast and in some
valleys this afternoon with most VIS above 5 miles below the cloud
bases. Stratus will expand again this evening and cover all valley
locations by 07Z Thu with bases 1500-2500 ft MSL and tops to 3500 ft
MSL. Slow clearing will occur again Thu, with some coastal areas
remaining cloudy Thu afternoon.

Mountains/Deserts...Areas of clouds at/above 9000 ft MSL will
continue through 04Z Thu. Isolated -SHRA will occur mainly in the
San Bernardino County mountains and adjacent high deserts and
Riverside COunty mountains through 04Z Thu, along with a slight
chance of -TSRA. West winds will gust locally 25-35 kt through
mountain passes into adjacent desert slopes after 23Z and continuing
through 16Z Thu.
.

&&

.MARINE...
No hazardous marine conditions are expected through Monday.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.

&&

$$

PUBLIC...Moede
AVIATION/MARINE...Maxwell