217
FXUS66 KSGX 220951
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
251 AM PDT Sun Sep 22 2024

.SYNOPSIS...
Warming trend for early this week. The marine layer will become
shallower early this week, becoming confined to the coast and
portions of the western valleys. For the middle to end of the week,
minor daily fluctuations in high temperatures are expected.

&&

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

Visible satellite at 2 AM was showing low clouds had filled in along
the coast and were reaching into portions of the western valleys.
High temperatures today will reach the mid to upper 70s for
coastal areas, the 80s to low 90s for the valleys, 70s to low 80s
for the mountains, low 90s for the High Desert, and 100 to 105
degrees for the low desert. Additional warming is expected into
Monday, with most places 3 to 5 degrees warmer than today. For
Tuesday, the latest guidance has highs similar to Monday for most
locations with only a degree or two of difference.

For the middle of the week, a trough of low pressure will build off
the US West Coast with a ridge of high pressure over the desert
southwest. There remains uncertainty in the upper level pattern and
which system will have the most influence over Southern California`s
weather. The current forecast follows the NBM and has slight day to
day temperature variations for Wednesday through Friday with more of
a cooling trend for the weekend. Temperature guidance for the
upcoming weekend shows increasing spread for coast and valley
locations from Friday through Sunday. That spread indicates
temperatures may trend warmer or cooler than currently forecast as
the models single in on a solution.

The marine layer will become shallower through Wednesday. Low
clouds and fog will be mostly confined to the coastal areas,
inland Orange County and the western portions of the San Diego
County valleys. Depending on how the upper level pattern shakes
out, the marine layer may recover slightly for the middle to end
of the week. If the troughing pattern becomes dominate over
Southern California for next weekend, the marine layer may deepen
far enough for low clouds and fog to reach portions of the Inland
Empire.

&&

.AVIATION...
220900Z...Coasts/Valleys...Low marine stratus based near 1000-1500ft
MSL (topped to 2000-2500ft MSL) continues to gradually fill in in
the San Diego hills/valleys and into Orange County at this hour.
There remains a 40% chance for CIGs and/or reduced VIS at KONT (and
a 20% chance for KSBD) after 12-13z. Local vis 1-3SM in BR for
higher coastal terrain and valleys. Low clouds clear to beaches by
17-18z, giving way to mostly clear skies through this evening. Low
clouds push back ashore in San Diego County after 00z, closer to 06-
09z for Orange County. These will have similar bases/tops but may
be 100-200ft lower than this morning.

Mountains/Deserts...Mostly clear skies with unrestricted VIS
expected through Monday morning.

&&

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

&&

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


&&

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

&&

$$

PUBLIC...CO
AVIATION/MARINE...Munyan