208
FXUS66 KSGX 032340
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
340 PM PST Tue Mar 3 2026

.SYNOPSIS...
Brief warming today, with cooling conditions and increased westerly
winds on the desert mountain slopes into the deserts Wednesday into
Thursday. The marine layer will deepen into Thursday, spreading low
clouds and fog into the valleys. Periods of northeasterly Santa Ana
winds and warmer conditions this weekend, with less marine layer low
clouds and fog. Moisture from the east could bring some showers for
Sunday and Monday.

&&

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

Visible satellite at 11 AM was showing mostly clear skies over land,
with marine layer low clouds well offshore. Weak transient ridging
will build over Southern California today, bumping temperatures 3 to
7 degrees warmer than yesterday west of the mountains. In the
deserts, temperatures are forecast to be similar to a degree or two
cooler than yesterday. The upper level ridging will be short lived,
as an upper level low pressure system moves into the Pacific
Northwest Wednesday into Thursday, pushing the ridge east.

The approaching low will begin to spread cooling inland Wednesday
with high temperatures for the coast and valleys a few degrees
cooler than today. Much greater cooling will spread inland on
Thursday with high temperatures 10 to locally 15 degrees cooler for
the deserts onto the desert slopes of the mountains. In addition to
cooler conditions west to northwest winds will increase over the
desert mountain slopes and locally into the deserts Wednesday night
into Thursday. Current forecast has gusts mainly 45 to 55 mph with
isolated gusts to 65 mph. Winds will weaken and quickly turn
northerly by Thursday afternoon. Mostly weak Santa Ana winds are
expected on Friday. By Saturday the low that brought us the gusty
onshore winds is expected to break off from the mean flow and
retrograde to our southwest, strengthening the offshore pressure
gradient. Ensemble guidance is currently showing the strongest north
to northeasterly winds on Saturday, with a slight weakening into
Sunday. For Saturday there is a 90 percent chance of weak Santa Ana
winds, 70 percent chance of weak to locally moderate winds, and a 40
percent chance of moderate strength winds. For Sunday, chances of
weak winds is the same, with a 45 percent chance of weak to locally
moderate winds, and a 20 percent chance of moderate winds. Both days
have a 5 percent or less chance of moderate to locally strong winds.

With the low positioned to the southwest on Sunday night, it will
have the opportunity to entrain moisture. This will at least
bring enough moisture the area to increase cloud coverage. There
is some potential enough moisture may be present to produce some
showers. Current forecast for Sunday and Monday follows the NBM
with a slight chance of showers, with highest chances over the San
Diego county mountains. By Sunday, 58 percent of ensemble
clusters are showing the low in a position (to our southwest and
off the coast of Baja) to bring precipitation over parts of
Southern California with a similar output for Monday. The rest of
the solutions are drier with the low further east over the Baja
Peninsula.

Highs on Friday will warm the most at the coast, with minimal change
or cooler conditions expected in the deserts due to the cold air
advection from the Great Basin. A warming trend will continue
through the weekend, with the most noticeable warming at the coast
due to the prevailing offshore flow. The offshore flow will also
keep marine layer low clouds and fog from developing.

&&

.AVIATION...
032340Z....Coast/ western valleys...VFR persists through this
evening. Low clouds will begin making their way in along the SD
County coast after 04Z, filling into the valleys by 09Z and spread
north over the Orange County coast 11-12Z. Bases will be around
1,000-2,000 ft MSL, dropping to 200-700 ft MSL with vis 3-5SM 10-14Z
at coastal sites.

Everywhere else...VFR conditions with some high clouds AOA 25,000 ft
MSL.

&&

.MARINE...
Stronger northwest winds will return late Wednesday and last into
Thursday, producing choppy conditions that may become hazardous.
Otherwise, no hazardous marine conditions are expected through
Saturday.

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory from 10 PM Wednesday to 10 AM PST Thursday for
     Apple and Lucerne Valleys-Riverside County Mountains-San
     Bernardino County Mountains-San Diego County Deserts-San
     Diego County Mountains-San Gorgonio Pass near Banning.

PZ...None.

&&

$$

PUBLIC...CO
AVIATION/MARINE...Villafane

NWS San Diego (SGX) Office