National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS66 KSGX 130400
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
900 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...

.Evening update...
Low clouds have already filled in across much of the inland
valleys this evening, although in some areas it didn`t clear much
to begin with. Clouds will spread further into the coastal
mountain slopes tonight as the marine layer continues to deepen. Breezy
onshore flow is occurring across the mountains and deserts with
gusts mostly 25-45 mph, strongest below the San Gorgonio Pass.
Winds will slowly weaken overnight.

Previous discussion...
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...
130300Z...Coast/Valleys...Widespread low clouds persist in the
coastal areas and valleys this evening with narrow breaks evident
on satellite. Bases are at the top of MVFR or just above 2800-
3500 FT AGL and tops of 4000 feet. Areas of drizzle are expected to
develop in the southerly flow along the coast overnight and early
Saturday. The main rain band and frontal wind shift is forecast for
23 UTC Saturday to 04 UTC Sunday.


Mountains/Deserts...Mostly clear skies and unrestricted visibility
will prevail through this evening with terrain obscurations up to
4000 feet increasing overnight. Surface gusts 20-30 kt will
continue in mountain passes and into the desert floor overnight and
decrease during Saturday morning. LLWS over and east of the
mountains. Local areas of dust due to the wind.

&&

.MARINE...
No hazardous marine conditions are expected through Saturday, though
drizzle will occur Saturday morning and then a frontal band with a
period of rain showers and a wind shift Saturday afternoon and early
evening. A secondary band of rain for Sunday afternoon with the main
upper level trough. Occasional gusts from the south at 20 knots
shifting to the west late afternoon Saturday and continuing into
Sunday.

&&

.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...SS/EA
AVIATION/MARINE...AOT