731
FXUS66 KSGX 022127
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
127 PM PST Tue Dec 2 2025

.SYNOPSIS...
The marine layer will deepen overnight into Wednesday morning before
becoming shallower again for Thursday into early next week. Areas of
drizzle or light rain near the coast are possible tonight into
Wednesday, with no impacts expected. Wednesday will be a few degrees
cooler than today, before warmer conditions Thursday into early next
week. The pressure gradient will rapidly switch from onshore to
offshore for the middle to end of the week with periods of gusty
Santa Ana winds.

&&

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

The marine layer is expected to rapidly deepen tonight as a low
pressure system moves south into the Great Basin. By Wednesday
morning, the marine layer is expected to be about 4500 ft deep with
low clouds reaching the coastal slopes of the mountains. There could
be some light showers or patchy drizzle late tonight into early
Wednesday morning for the inner coastal waters into adjacent coastal
areas with the chance of measurable rainfall less than 10 percent.

As the upper level low digs into the Great Basin a 1030 mb surface
low will develop. This will bring periods of gusty Santa Ana winds
to foothills and coastal mountain slopes; warming conditions; and
mostly clear skies across the area. Gusty north winds will develop
through and below the Cajon Pass on Wednesday afternoon with more
widespread and stronger northeasterly winds for Wednesday night into
Thursday morning along and below the coastal slopes of the mountains
with peak gusts 40 to 50 mph, locally up to 55 mph. Northeast to
east winds will continue for Thursday afternoon into Friday morning,
but with decreasing coverage and strength. Gusts on Friday are
expected peak at 35 to 40 mph. Lowest daytime humidity on Thursday
and Friday for the valleys and inland coastal areas will fall to 15
to 20 percent.

A few degrees of cooling is expected into Wednesday, with highs a
few degrees below average. A gradual warming will occur Thursday,
with further warming expected through the weekend into early next
week. By Tuesday, highs will be 10 to 15 degrees above average for
inland areas.

&&

.AVIATION...
021700Z....Coasts/Valleys...SKC through the afternoon. Low clouds
based 600-1200 ft MSL return to San Diego County 00-03Z Wed. Bases
will rise steadily overnight to 2000-2500 ft MSL as coverage expands
to include the entire coastal basin. Patchy -DZ expected, especially
near the coastline from 10-16Z. Clouds scatter out 15-18Z. North to
northeast winds gusting 20-30 kts through and downwind of the Cajon
pass after 18Z (including vtcy KONT).

Mountains/Deserts...VFR conditions through the period with FEW-SCT
high clouds AOA 20 kft. West winds gusting 25-40 kts through
mountain passes and along east-facing slopes after 03Z Wed. Winds
briefly weaken 15-18Z before turning north to northeast.

&&

.MARINE...
No hazardous marine conditions are expected today through Saturday.

&&

.BEACHES...
Astronomical high tides are forecast to occur each morning Wednesday
through Friday, threatening minor tidal overflow and beach erosion.
Chances of these impacts are higher Wednesday and Thursday mornings
as elevated surf up to 4-6 feet combines with the high tides, mostly
in San Diego County. Check the Coastal Hazard Message for details.

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement from 10 PM PST this evening through
     Friday morning for Orange County Coastal Areas-San Diego
     County Coastal Areas.

PZ...None.

&&

$$

PUBLIC...CO
AVIATION/MARINE/BEACHES...KW