396
FXUS66 KSGX 141642
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
942 AM PDT Mon Jul 14 2025

.SYNOPSIS...
High pressure across California will bring slight warming today.
High pressure will weaken for Tuesday and Wednesday with Wednesday
high temperatures as much as 8 to 12 degrees below average for the
valleys. For Thursday and Friday, a weak upper level low pressure
from the south will bring an increase in monsoonal moisture with a
chance of afternoon showers and thunderstorms, mainly for the
mountains and high desert with the greater chances on Friday.
Chances will slowly decrease during next weekend as the monsoonal
moisture slowly decreases. Night and morning coastal low clouds
will spread into the western valleys late each night.

&&

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

Update: The marine layer is continuing to dissipate from east to
west, although there is more coverage than the previous night with
all of the coastal areas still being overcast as of 9 AM this
morning. Clearing will likely be a little later this morning due to
this, but most locations should scatter out completely by Noon. The
marine layer should thicken up and lift over the next couple of
nights, and although it is a very slight chance, some of these
clouds may thicken up just enough to allow for some light drizzle,
especially either tonight or tomorrow night. Temperatures will also
be notably cooler today, and even cooler tomorrow into Wednesday. In
general, there is very little change in the overall pattern, with
Friday still appearing to be the best chance for a few afternoon
thunderstorms to form over the mountains and deserts as mid-level
monsoonal flow infiltrates the region, with the most likely
locations being over the San Bernardinos. The chance of
thunderstorms is going to continue to drop off, with a gradual
warming trend, going into the weekend.

.SHORT TERM (Today through Wednesday)...
High pressure across California will bring slight warming to
inland areas today with high temperatures as much as 5 to 10
degrees above average for the Apple and Lucerne Valleys and as
much as 5 to 10 degrees below average for the western valleys.
High temperatures today will range from around 70 near the coast
to the mid 80s to upper 90s for the Inland Empire with 110 to 114
for the lower deserts.

High pressure will begin to weaken on Tuesday and Wednesday with
high temperatures on Tuesday as much as 4 to 8 degrees cooler for
the mountains and high deserts with most areas another few degrees
cooler on Wednesday. With the cooling, high temperatures on
Wednesday will be around average for the lower deserts and as much
as 8 to 12 degrees below average for the valleys. High
temperatures on Wednesday will range from around 70 near the
coast to the 80s to around 90 for the Inland Empire with 104 to
108 for the lower deserts.

The marine layer will remain near 1500 to 2000 feet deep with
night and morning coastal low clouds spreading into the western
valleys late each night.

&&

.LONG TERM (Thursday through Sunday)...
A weak upper level low pressure system off the Pacific coast of
central Baja will move slowly northward bringing an increase in
monsoonal moisture into southern California on Thursday and
Friday. NBM daily chances for measurable precipitation at Big Bear
increase to around 15 percent on Thursday and 25 percent on
Friday. There are chances for mainly afternoon showers and
thunderstorms, mainly for the mountains and high desert on
Thursday and Friday with the greater chances on Friday.

Monsoonal moisture will begin to decrease next weekend along with
chances for afternoon showers and thunderstorms with slightly
warmer high temperatures for next weekend as the drying occurs.
High temperatures for next weekend will be a few degrees above
average for the deserts and as much as 4 to 8 degrees below
average for portions of the valleys. High temperatures for next
Sunday will range from the lower 70s near the coast to the upper
80s to upper 90s for the Inland Empire with 107 to 111 for the
lower deserts.

&&

.AVIATION...
141640Z....Coast/Valleys...Low clouds based 900-1500 ft MSL that
surged inland overnight are scattering out nicely, full scattering
to the coasts expected by 17-18z. A few patches of clouds may stick
around the beaches, but otherwise, VFR prevails through this
evening. Low clouds push back ashore around 00-03Z Tuesday with
similar bases and tops, then moving ~20 miles inland late tonight.

Mountains/Deserts...FEW-SCT shallow Cu possible at 10-12 kft AGL
over the mountain ridges this afternoon. Otherwise clear with
unrestricted vis through tonight.

&&

.MARINE...
No hazardous marine conditions expected through Friday.

&&

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


&&

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

&&

$$

UPDATE...Stewey
PUBLIC...17
AVIATION/MARINE...Munyan