274
FXUS66 KSGX 121147
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
347 AM PST Wed Nov 12 2025

.SYNOPSIS...
Low clouds and fog may reach the far western valleys early this
morning with lower visibilities mostly near the mesas into the far
western valleys. Cooling will continue to spread inland today and
Thursday with greater cooling on Friday. Periods of precipitation
are expected for Thursday night through the weekend. The
precipitation could be locally heavy at times for late Friday into
Sunday. Another round of more widespread precipitation is
possible for Monday into Tuesday.

&&

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

.SHORT TERM (Today through Friday)...
The NKX sounding for late Tuesday afternoon showed the shallow
marine layer had deepened a few hundred feet. Low clouds and fog
one again cover coastal areas and may reach the far western
valleys early this morning. Visibilities have improved some near
the coast versus the past two mornings with the lower visibilities
mostly near the San Diego County mesas early this morning. High
clouds continue to spread across the area with that sounding also
showing a deep moist layer from 400 mb to 200 mb.

High temperatures will continue to cool for today and Thursday
with Thursday high temperatures within a few degrees of average
for the coast and valleys and around 4 to 8 degrees above average
for the deserts. There will be greater cooling on Friday with high
temperatures for the coast and valleys as much as 5 to 10 degrees
below average with the deserts near to around 5 degrees below
average.

There continue to be model differences with the evolution and
details of what is expected to be a cooler and wetter pattern for
late this week into next week. Model guidance is now showing the
chance for generally lighter precipitation for Thursday night
into Friday morning with increasing chances for heavier rainfall
for later on Friday into Saturday.

Snow levels will mostly remain above 10000 feet through Thursday,
then gradually fall to around 9500 feet on Friday and and 7500
feet on Saturday.

&&

.LONG TERM (Saturday through Tuesday)...
Through the weekend, NBM deterministic rainfall has continued to
increase. For Orange and southwestern San Bernardino Counties, it
now ranges from around 2.5 inches near the coast to 3 to 5 inches
for the mountains with locally greater amounts. For San Diego
County it now ranges from 2 to 2.5 inches near the coast to 3 to
4 inches for mountains with 1 to 2 inches for the high desert and
around 1 inch for the lower deserts. Chances for greater rainfall
amounts are highest on Saturday, followed by Friday and Friday
night. Chances for thunder are greatest for Saturday morning
through evening.

The ECMWF Extreme Forecast Index for rainfall for late Friday
afternoon to late Saturday afternoon reaches the 70th to 80th
percentile for much of southwestern California and for late
Saturday afternoon through late Sunday afternoon mostly the 80th
to 90th percentile.

The model spread grows for next week with another round of
relatively more significantly precipitation possible for late
Monday into Tuesday. Beyond Tuesday, cluster analysis shows
ensemble members with high pressure off the West Coast and
northwest flow aloft over California are the drier solutions while
those ensemble members slower to move low pressure to the east of
California wetter.

&&

.AVIATION...
121030Z...Coasts/Western Valleys...Low clouds 400-1000 feet MSL,
tops to 1700 feet, and vis mostly 0-5SM, lowest inland, will
continue to spread into western valleys this morning. Scatter out
around 17-18Z, with patchy intermittent low clouds around 1500 feet
MSL to linger thereafter. Areas of low clouds will redevelop after
01Z, but random and intermittent in coverage. Bases should rise to
around 1500-2000 feet MSL overnight into Thursday.

Otherwise...VFR conditions will continue today and tonight. BKN high
clouds AOA 20 kft will gradually lower to 12-15 kft by Thursday.

&&

.MARINE...
A storm system will approach Friday and move through Saturday,
boosting southerly winds and seas, but currently they do not appear
to rise to hazardous levels. There is a slight chance of
thunderstorms Friday afternoon through Saturday.

&&

.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...17
AVIATION/MARINE...MM