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000
FXUS66 KSGX 222059
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
159 PM PDT Mon Apr 22 2024

.SYNOPSIS...
Cooler temperatures, widespread low clouds and periods of gusty
onshore winds will occur this week. Patchy drizzle will be
possible west of the mountains Tuesday morning, with additional
drizzle or light showers possible Wednesday night into Thursday,
and again Thursday night into Friday. Subtle warming sets in this
weekend.

&&

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

A weakening ridge axis is moving eastward and a closed low will
progress southeastward through the eastern Pacific today. Low
clouds are very slow to clear today, but have started to make
progress over the valleys over the last half hour. As a result,
current temperatures are in the upper-50s to low-60s across the
coast and western valleys, and areas that remain under cloud cover
will remain close to those temperatures through the afternoon.
Elsewhere, skies are mostly clear, save for a few cumulus clouds
forming in the mountains. Temperatures are quite a bit cooler this
afternoon than on Sunday, and further cooling is expected on
Tuesday. Highs will top out 3-6 degrees below normal across the
coast, valleys and coastal slopes on Tuesday, while remaining 2-5
degrees above normal across the desert slopes and deserts.

Night and morning low clouds will be abundant this week as onshore
flow persists. The marine layer may be deep enough to produce
patchy drizzle west of the mountains late tonight into Tuesday
morning.

The closed low developing to our southwest will meander over the
next few days before becoming an open wave and passing over
Southern California or northern Mexico Wednesday into Thursday.
Gusty winds will result over the mountains and deserts, with peak
gusts of 50-60 mph, especially Wednesday night into Thursday.
Drizzle or light showers will also be possible as the marine layer
deepens rapidly Wednesday night into Thursday, and again Thursday
night into Friday.

The forecast for the end of the week into next weekend remains
hazy. Cluster analysis seems to agree on longwave troughing and
negative height anomalies, signaling cool conditions and a deep
marine layer through Friday. By Saturday, substantial differences
emerge in the strength and location of an upper low moving through
the western US, and how quickly a potential ridge could lead to
slight warming over the region. As of right now, the forecast
calls for gusty onshore winds over the mountains, deserts and
coastal waters, though a slight chance of showers cannot be ruled
out if the low tracks a little farther west. Stay tuned as the
forecast is refined in the coming days.

&&

.AVIATION...
222020Z...Coast/Valleys...Low clouds with bases around 800-1000 feet
MSL and tops to 2000 feet will cover coastal areas and parts of
inland valleys. VIS 4-6SM along inland extent of clouds and over
higher coastal terrain. Low clouds to push inland after 00Z and
filling the entire coastal basin overnight into Tuesday. Bases would
be around 1000-1800 feet MSL, with vis restrictions along inland
edge of cloud and in higher valleys and foothills.

Mountains/Deserts...Mostly clear skies with unrestricted VIS today
and tonight.

&&

.MARINE...
No hazardous marine conditions are expected through Friday. Stronger
winds and possibly hazardous conditions Friday night.

&&

.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...EA
AVIATION/MARINE...Small