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000
FXUS66 KSGX 232042
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
142 PM PDT Tue Apr 23 2024

.SYNOPSIS...
A cooling trend will continue through Thursday with periods of
stronger and gusty southwest to west winds continuing for the
mountains and deserts through Friday evening. A deep marine layer
will continue into Friday with some light precipitation from
drizzle or light rain possible from the coast to the coastal
slopes of the mountains, mostly during nights and mornings. Then
warmer and drier with weaker winds for Saturday through Monday
with Sunday high temperatures around average and Monday high
temperatures around 5 degrees above average.

&&

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

A closed low at 500mb will continue to move eastward over the
Pacific, moving inland over SoCal sometime late Wednesday Night
into Thursday morning. Following this low, a second low pressure
system will dig in over the western United States Thursday through
Saturday. This will maintain onshore flow for much of this week,
leading to cooling temperatures, extensive marine layer clouds,
and gusty winds for the mountains and deserts through much of this
week.

This morning’s marine layer deepened to roughly 4000-4500 FT with
low clouds extending well inland, even up into the Cajon Pass.
Some areas of drizzle were also noted across much of the Inland
Empire, inland Orange County, and the San Diego County Valleys.
With onshore flow essentially locked in for the next several days
and an already deep marine layer in place, there will be
persistent chances for drizzle each night through Thursday night.

As implied by the continued onshore flow, there will also be
periods of gusty west to southwest winds over the mountains and
desert foothills during the afternoons and evenings. Winds do look
to trend a bit stronger each day through Friday, and Wind
Advisories may be needed starting tomorrow afternoon, with the
strongest winds occurring Friday afternoon/evening. Peak wind
gusts of 40-60 mph will be common, with higher gusts over 60 mph
occurring over mountain ridgelines, below passes, and through
wind-prone canyons.

This weekend through early next week will see weak ridging at
500mb slowly yet steadily build into the region. This will support
warming and drying through early next week. Temperatures look to
be at their warmest on Monday, when highs may top out a few
degrees warmer than seasonal normals. This would also be
accompanied by a shallower marine layer, with low clouds and fog
becoming more and more confined to the coast.

&&

.AVIATION...
232030Z...Coast/Valleys/Foothills...Expect inland clearing with
partial clearing in the coastal areas through 22-01Z. CIGs around
2000-3000 feet could impact coastal airports through afternoon. Low
clouds to push inland and fill the coastal basin to foothills again
after 01Z into early Wednesday. Low clouds with bases 1500-2500 feet
MSL, locally down to 1000 feet in -DZ, and tops to 4000 feet are
expected again overnight and early Wednesday Morning. VIS 0-5SM
inland, where clouds and terrain intersect obscuring foothills.

Mountains/Deserts...Mostly clear skies (above 4000 feet MSL on
coastal slopes) with unrestricted VIS today and tonight.

&&

.MARINE...
No hazardous marine conditions are expected through Thursday.
Stronger northwest winds and choppy seas arrive late Thursday and
continue into early Saturday, likely generating hazardous conditions
at times, especially in the outer waters.

&&

.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory from 5 PM Wednesday to 11 PM PDT Friday for Apple
     and Lucerne Valleys-Coachella Valley-Riverside County
     Mountains-San Bernardino County Mountains-San Diego County
     Deserts-San Diego County Mountains-San Gorgonio Pass Near
     Banning.

PZ...None.

&&

$$

PUBLIC...Adams
AVIATION/MARINE...Suk