094
FXUS66 KSGX 220459
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
859 PM PST Wed Jan 21 2026

.SYNOPSIS...
A cooling trend will continue through Friday. There will be chances
of precipitation for locations over and west of the mountains
Thursday through Saturday morning. Dry conditions are expected to
return Sunday with a warming trend and periods of offshore flow
expected into next week.

&&

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

Widespread mid and high clouds cover the region this evening with
a few low clouds west of the mtns. The lack of low clouds is
likely due to a weak marine layer inversion allowing mixing of the
marine layer air with the dry air above. The afternoon sounding
also shows a dry layer from about 2,000-15,000 feet with
increasing moisture above. Radar is showing echoes just west of
San Clemente Island but any precip falling is not likely to reach
the ground...yet.

From previous discussion...
Onshore flow will strengthen as a low pressure system continues
to move south parallel to the California coast before moving east
into Baja California late Friday/early Saturday. The increased
onshore flow will enable areas of low clouds and fog that develop
overnight to reach well into the valleys and along coastal slopes
of the mountains.

The low pressure system will also bring slight chances of showers
to the area Thursday through early Saturday. Scattered showers
could begin as early as Thursday morning, with rain likely
continuing into Friday. About 50 percent of ensemble solutions
keep the potential of rain over the area into at least Saturday
morning. Latest high resolution guidance is indicating hourly
rainfall rates will range from 0.05-0.25" per hour. Rates at or
near 0.25" per hour will be fairly isolated and most likely occur
Friday. Chances of rainfall totals exceeding 0.50" from Thursday
through Saturday, are 10-20 percent for the coast and valleys and
30-40 percent in the mountains. The mountains have a 10-15 percent
chance of exceeding 1 inch of rain. Snow levels will fall to 6500
to 7000 ft by Saturday morning. 1-3" of snow are expected around
7000 ft, with slightly higher totals expected above 8000 ft.

Today is trending cooler than yesterday, with further cooling
expected into Friday. By the weekend, conditions west of the
mountains are expected to warm a few degrees with continued cooling
in the deserts. By Monday, widespread warming is expected with
increasing temperatures each day into next Wednesday. Ensemble
guidance is in agreement that a ridge of high pressure will set up
over the West Coast on Monday and remain in place into next
Wednesday. With the upper level low to our east by Sunday,
offshore winds are expected to develop. Current ensemble guidance
has an 80 percent chance of weak offshore winds developing, with a
20 percent chance of weak to moderate offshore winds developing.

&&

.AVIATION...
220400Z....Coast/Valleys...Low clouds lingering just offshore
currently with bases around 800-1200 ft MSL. Clouds will slowly
move inland from 06-12Z Thu, filling into most of San Diego/Orange
County coasts and valleys. Bases rising to 1500-2000 ft
overnight. Clouds will likely reach into portions of the Inland
Empire after 09Z. 70% chance for cigs at KONT and 40% at KSBD. Low
cloud scatter to the coast 15-18Z. Low clouds may struggle to
return early Thursday evening, but should eventually fill most of
the coastal basin by late Thursday night with bases above 2000 ft
MSL.

.Otherwise...Variable high clouds around 20 kft, lowering to around
10 kft by Thursday morning. Isolated -SHRA after 18Z Thu (more
likely west of the mountains), but any impacts to cigs/vis should be
minimal and brief if they occur.

&&

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

&&

.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/CO
AVIATION/MARINE...KW

NWS San Diego (SGX) Office