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000
FXUS66 KSGX 131638
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
938 AM PDT Sat Apr 13 2024

.SYNOPSIS...
Periods of rain, mountain snow, and gusty winds are expected today
and tomorrow. Below average temperatures will prevail this weekend.
Dry and warming conditions expected for next week.

&&

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

Visible satellite imagery at 9 AM was showing widespread low cloud
coverage from the beach to the coastal mountain slopes, locally into
mountain passes. A low pressure system off the coast of Northern
California, just west of San Fransisco will influence our weather
this weekend. As the system moves east and south two embedded
shortwaves will bring periods of precipitation and gusty westerly
winds to the area.

The first shortwave will arrive this afternoon, bringing a narrow
ribbon of weak IVT with it. Showers will begin in Orange and San
Bernardino counties this afternoon, with shower activity moving
south and east through about midnight. Showers are expected to reach
Riverside and San Diego Counties by this evening. Precipitation will
be generally light, with peak rainfall rates of 0.10-0.15 inches per
hour for lower elevations with rates up to 0.20 inches per hour in
the mountains.

A dry period can be expected for Sunday morning ahead of the second
shortwave. The second shortwave is forecast to arrive Sunday
afternoon. There will be less available moisture associated with the
second wave, so showers will not be as widespread as today and more
scattered in coverage. Precipitation on Sunday will again be
generally light.

Rainfall totals will range from 0.05-0.30" in the coastal and valley
zones, with the higher end of the range in Orange and San Bernardino
Counties, and the lower amounts in San Diego County. In the
mountains from 0.25-1.00" is forecast, highest in San Bernardino
County and lowest in the San Diego County mountains. A few hundreds
of an inch is all that will fall in the High Deserts. The Lower
Deserts will remain dry. Snow levels around 5500-6500 feet today
will fall to 4500-5500 feet Sunday. Snow totals of 3-7" possible
above 7000 feet in San Bernardino County Mountains.

Periods of gusty winds are expected this weekend. Peak gusts of 40-
60 mph are expected in the afternoons and evenings today and Sunday.
Strongest winds will occur in the mountains and deserts. Breezy
southwest winds will also impact the coastal and valley zones with
gusts to 25 mph. A second round of gusty winds will develop Sunday
afternoon and evening as the second shortwave passes over Southern
California.

The low quickly moves to the east on Monday, and ensemble guidance
supports warming over Southern California through the middle of next
week.

&&

.AVIATION...
131530Z...Coast/Valleys...Widespread BKN/OVC clouds will prevail
through Sun morning with bases 2500-4000 ft MSL and tops to 6000-
10000 ft MSL. Local VIS 3-5 mi will occur in SHRA mainly 22Z Sat-05Z
Sun.

Mountains/Deserts...Areas of terrain obscurations will occur at
times mainly on the coastal slopes in clouds/SHRA/SHSN through Sun
morning. Surface gusts 25-45 kt from the S/W will continue from the
mountain crests through the desert slopes and into the deserts
through 12Z Sun, with increasing winds again after 18Z Sun, along
with LLWS and MOD UDDFS.

&&

.MARINE...
South winds will develop this morning and will be associated with
gusts between 20 and 25 knots at times, including near Zuniga
Jetty/San Diego Bay Entrance, until the front arrives from the west
late this afternoon/early this evening when a few gusts 20 to 25
knots will also occur. A Small Craft Advisory has been issued for
these gusts 8 AM-8 PM for the inner/outer coastal waters (0-60 NM
from the coast). Otherwise, a couple periods of rain showers will
occur late today/this evening and Sunday late afternoon/evening.
Local gusts over 20 knots could also occur Sunday and Monday from
the west. Winds will be lighter beginning Tuesday.

&&

.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 Bernardino County Mountains.

     Winter Weather Advisory until 8 PM PDT Sunday for San Bernardino
     County Mountains.

     Wind Advisory from 3 PM this afternoon to 11 PM PDT this evening
     for Riverside County Mountains-San Diego County Deserts-San
     Diego County Mountains-San Gorgonio Pass Near Banning.

PZ...Small Craft Advisory until 8 PM PDT this evening for Coastal
     Waters from San Mateo Point to the Mexican Border and out
     to 30 nm-Waters from San Mateo Point to the Mexican Border
     Extending 30 to 60 nm out including San Clemente Island.


&&

$$

PUBLIC...CO
AVIATION/MARINE...Suk