436
FXUS66 KSGX 231539
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
839 AM PDT Mon Sep 23 2024

.SYNOPSIS...
Today will be dry and warmer, with high temperatures around 4 to
8 degrees above average for inland areas. Not much change on
Tuesday then slightly cooler for Wednesday and Thursday. Friday
may be a little warmer, followed by slow cooling for next weekend
with increasing spread in the high temperature guidance due to
the uncertain placement of a weak low pressure system in the
vicinity of southern California. Night and morning coastal low
clouds will spread into portions of the western valleys late each
night.

&&

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

This morning...The marine layer is almost 2000 ft deep, with low
clouds and fog extending 15-20 miles inland. Visibility less than
1 mile in fog is likely where clouds and terrain intersect. The
inversion is stronger than yesterday so clearing may be a little
slower and low clouds are more likely to persist at the beaches
into this afternoon.

Weak low pressure trough over SoCal with a closed upper low about
200 miles to the west. The low pressure trough will continue to
weaken and high temperatures today will be around 5 degrees
warmer than Sunday, near average near the coast to 4 to 8 degrees
above average inland, mostly into the 90s for the inland valleys
and 102 to 108 for the lower deserts. Not much change is expected
for Tuesday, then a weak low pressure system off the California
coast may bring a few degrees of cooling for Wednesday and
Thursday as the upper high gets displaced eastward into the Great
Basin.

That weak low pressure system may move farther off the California
coast on Friday allowing the upper high to expand westward, with
high temperatures slightly warmer. For next weekend, that weak low
pressure system may move back towards southern California with
differences in model placement and timing. The deterministic NBM
has slight cooling for Saturday and Sunday, but with increasing
spread in the high temperature guidance.

&&

.AVIATION...
231455Z...Coasts/Valleys...Low marine stratus (based around 600 -
900 ft MSL, tops to near 1500 ft MSL) with vis 1-3SM in BR for
higher coastal terrain and valleys. Scattering out will occur for
most locations by 16-18z, though some stratus may linger near the
beaches through the afternoon. Confidence in clearing time at KSAN
of 23/1730z is moderate.

Low stratus builds in again for coastal sites around 02-05z this
evening with similar bases and tops.

Mountains/Deserts...Mostly clear skies with unrestricted VIS
expected through Sunday evening.

&&

.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...PG
AVIATION/MARINE...Small