475
FXUS66 KSGX 122022
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
122 PM PDT Sat Jul 12 2025

.SYNOPSIS...
Slightly cooler conditions today followed by a slight
rebound in temperatures for Sunday and Monday. Gradual cooling back
to near average for mid July expected for the middle to the end of
next week. While chances are still low and uncertainty remains, some
confidence is increasing for the potential of monsoonal
thunderstorms over the mountains late next week. Night and morning
low clouds will spread across the coastal areas and into the western
valleys late each night.

&&

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

The dominant upper ridge in control of the region`s weather is
currently displaced just off the California and is also a tad weaker
than it was earlier in the week. This and a modestly deep marine
layer to ~2000ft is limiting high temperatures to 5 to locally 10
degrees below average west of the mountains, while the deserts stay
~5 degrees above average. Coasts today top out in the 70s with
inland valleys generally in the mid to upper 80s, while the Inland
Empire will reach the low 90s. Deserts staying hot with high
temperatures 105 to 110 degrees. The ridge restrengthens and spreads
back overhead Sunday and Monday, leading to a rebound in
temperatures up about 5 degrees warmer than today. The marine layer
depth decreases some with the building ridge, but will still be
around 1500-2000ft deep.

By mid-late Monday, a shortwave trough rounding the upper ridge will
be on the southern periphery, which looks to place it across
northern Baja. While some monsoonal moisture will likely accompany
this shortwave, any convection will likely be limited to the
mountains in northern Mexico. While unlikely, a stray storm over the
extreme southern San Diego County mountains cannot be ruled out. By
Tuesday/Wednesday, this disturbance will have passed but should
leave the ridge weakened and displaced back to the eastern Four
Corners Region. This opens the door for a series of disturbances
Thursday through the end of the week. While model guidance continues
to show a fairly vast range of solutions in the exact placement of
the ridge and corresponding tracks of the aforementioned
disturbances, more ensemble members (notably out of the higher-
resolution ECMWF which were previously more dry in the last several
runs) are starting to coalesce around the chance of diurnal
monsoonal thunderstorms in the mountains possible each afternoon
Thursday-Saturday. Significant uncertainty in timing is muddling the
view here and a few more days of seeing how the pattern evolves is
necessary to say with much confidence who will see, or even if,
thunderstorms occur. There is still good agreement in a gradual
cooldown as a result of this pattern, which has many locations 5 to
10 degrees cooler on Wednesday compared to Monday.

&&

.AVIATION...
122010Z....Coast/Valleys...Skies have mostly cleared this afternoon,
with the exception of areas near Point Loma in San Diego.
Intermittent SCT-BKN clouds near 1,500 ft MSL expected VCTY KSAN
through the afternoon hours. BKN-OVC low clouds will surge inland
again this evening around 00-02Z. Bases starting near 1,500-1,800 ft
MSL will lower closer to 1,000-1,300 ft MSL after 04Z Sun with
similar inland extent of this morning. Confidence increasing VCTY
KONT seeing BKN cigs 700-900 ft MSL after 10Z Sun. Similar clearing
pattern expected on Sunday.

Mountains/Deserts...VFR conditions and unrestricted VIS through
this weekend.

&&

.MARINE...
No hazardous marine conditions expected through the middle of next
week.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.

&&

$$

PUBLIC...Munyan
AVIATION/MARINE...APR