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000
FXUS66 KSGX 122057
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
157 PM PDT Fri Apr 12 2024

.SYNOPSIS...
Colder this weekend, with periods of light showers and gusty winds
occurring through Sunday. Slight warming sets in by Monday, with
dry conditions expected through most of next week.

&&

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

A weakening closed low to the southwest is becoming absorbed into
the mean flow, and a 534 DM low is off the coast of northern
California this afternoon. Onshore flow has strengthened and a
persistent marine layer is producing widespread low cloud coverage
across the coast and valleys. Temperatures this afternoon are in
the upper-50s to mid-60s where there has been extensive cloud
cover, but are warming efficiently in the mountains and deserts
where skies are clear. Winds will continue to strengthen over the
mountains and desert slopes this afternoon, peaking through late
tonight.

The storm system to the north will elongate and continue to move
southward tomorrow, and a shortwave will pass just to the north of
our region on Saturday. Drizzle or very light rain showers will be
possible overnight across the coast and valleys, with minimal
accumulations expected. The shortwave will spark scattered showers
across Orange and San Bernardino Counties by Saturday afternoon,
with showers spreading farther south and east into Riverside and
San Diego Counties over the subsequent hours. Showers will largely
taper off late Saturday night into Sunday morning before the
parent storm system passes overhead on Sunday, igniting additional
showers. Very little moisture will make it to our region,
especially the farther south you go. Total rain amounts for this
weekend will range from 0.05-0.30" for the coast and valleys,
with the higher end of the range in Orange and San Bernardino
Counties, and the lower amounts in San Diego County; 0.25-1.00" in
the mountains, highest in San Bernardino County; and a few
hundreds of an inch in the High Desert, with the lower deserts
remaining dry.

Snow levels around 5500-6500 feet will occur through much of the
day on Saturday before falling to 4500-5500 feet on Sunday. The
highest accumulations of 3-7" will be possible above 7000 feet in
San Bernardino County.

Several rounds of gusty winds will also occur this weekend, in
conjunction with the waves passing overhead. The strongest round
looks to occur Saturday afternoon and evening in the mountains and
deserts, where gusts up to 55 mph will be possible. Breezy south
to southwest winds gusts up to 25 mph will even be possible
across the coast and valleys. A second round of gusty winds will
develop Sunday afternoon and evening as the parent low passes over
Southern California.

Cooling temperatures continue through the weekend, with the
coldest day of the week likely occurring on Sunday: highs will
reach the upper-50s to low-60s across the coast, valleys and High
Desert, the upper-30s to 40s in the mountains and low-70s in the
deserts.

The low quickly moves to the east on Monday, and ensemble guidance
supports warming over Southern California through the middle of
next week. Onshore flow will maintain the marine layer, with night
and morning low clouds forming west of the mountains most nights
and mornings.

&&

.AVIATION...
121910Z...Coast/Valleys...Widespread low clouds persist in the
coastal areas and valleys this afternoon, with bases 1500-2500 ft
MSL and tops to 3500 ft MSL with areas of VIS 3-5 miles in BR,
locally 1 mile in fog where clouds and terrain intersect. Clearing
is unlikely this afternoon in areas below about 2000 ft MSL. Low
clouds will spread farther inland tonight and Sat morning with bases
2000-3000 ft MSL and tops to 5000 ft MSL. SCT -SHRA likely to
develop Sat afternoon.

Mountains/Deserts...Mostly clear skies and unrestricted VIS will
prevail through this evening with terrain obscurations developing on
the lower coastal mountain slopes after 10Z Sat. Areas of west winds
with surface gusts 25-35 kt will continue through Sat morning,
producing weak up/downdrafts and LLWS over and east of the mountains.

&&

.MARINE...
No hazardous marine conditions are expected through Saturday, though
showers will occur Saturday morning into Sunday. Southerly winds
could gust locally to around 20 kts for a brief period on Saturday
afternoon then West wind gusts could locally exceed 20 knots Sunday
and Sunday night.

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory from noon to 11 PM PDT Saturday for Apple and
     Lucerne Valleys-San Bernardino County Mountains.

     Winter Weather Advisory from noon Saturday to 8 PM PDT Sunday
     for San Bernardino County Mountains.

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

PZ...None.

&&

$$

PUBLIC...EA
AVIATION/MARINE...PG