156
FXUS66 KSGX 061207 CCA
AFDSGX

Area Forecast Discussion...CORRECTED
National Weather Service San Diego CA
507 AM PDT Sun Jul 6 2025

.SYNOPSIS...
High temperatures near average with night and morning low clouds
closer to the coast can be expected through tomorrow. High
pressure over the Desert Southwest will build into the region for
Tuesday into later next week, bringing hotter weather for inland
areas. There will be a very gradual cooldown on Friday and then
temperatures holding steady through the weekend.

&&

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

Today through tomorrow...

The trough with an associated U/L low, which has been providing
cooler temperatures in place for the western half of the CWA, is
going to begin to fill and get absorbed back into the troughing to
the north through tomorrow. Simultaneously, the subtropical ridge
to the east of the region will begin to become more amplified and
the axis will begin to shift more westward towards SOCAL. This
will allow for temperatures to continue to become slightly warmer
through tomorrow, especially for the coastal and inland areas.
Gusty westerly winds due to the temperature gradient, and also the
surface pressure gradient during the afternoon hours will begin
to weaken a little each day as the trough (and thus gradient) also
weakens. Locations within the Inland Empire (IE) will reach into
the upper 90s by later in the day, and most locations along the
coast will likely top out in the 70s. The marine layer is going to
be similar this morning as to how it has been in previous days,
except that the cloud bases have slightly lifted, and may allow
for some of the inland valleys further east to get in on some of
the low clouds and foggy conditions early this morning. There will
also likely be some fog again for locations along the I-15
corridor in San Diego County. Patchy fog will also be possible
within some of the wind-sheltered valleys.

Tuesday through early next weekend...

By this time in the forecast period, the subtropical ridge will be
further shifting westward with a high pressure building at the
surface over Arizona. With 500 mb heights reaching nearly 600 dm for
our deserts, temperatures will continue to sore, especially for the
lower deserts. There will also be an increase of lower level
moisture with dewpoints climbing into the low 60s and higher
relative humidity values as a result by Wednesday, with weak recover
overnight into Thursday. This, in combination with very hot
temperatures likely exceeding 115F, is going to cause the heat
indices to climb with an increased heat risk potential. Due to this,
I`ve issued an Extreme Heat Watch for the lower deserts in San Diego
County, as well as the Coachella Valley, from Wednesday morning
through Thursday evening. Please plan ahead if you are traveling
through the deserts during this time and ensure that you have plenty
of water on hand. Temperatures elsewhere will also be notably
warmer, especially within the inland valleys. The IE will likely
have temperatures approaching the 100F degree mark on Tuesday, and
most locations getting into the low to mid 100s for both Wednesday
and Thursday.

By Friday, the ridge will only begin to weaken slightly with slight
influence of the troughing upstream to allow for temperatures to
cool very gradually going into the weekend. Ensembles and
deterministic models alike have relatively good agreement the the
ridge will just remain parked over the southwest region with
temperatures remaining nearly steady each day. It also appears
that any monsoonal moisture from the developing wind regime will
remain confined well to the east with no impacts to SOCAL through
then.

&&

.AVIATION...
060930Z....Coast/Valleys..A patchy and thin layer of low clouds
based 800-1200 ft MSL is slowly developing into inland areas and
Orange County. Clouds will move 10-15 miles inland, bringing vis
reductions 2-4 SM to elevated coastal terrain and western valleys.
Clouds clear 15-17Z Sun. Low clouds 900-1400 ft MSL reform and
move ashore again after 04Z Mon.

Mountains/Deserts...Mostly clear with unrestricted VIS through
Monday.

&&

.MARINE...
No hazardous marine weather conditions are expected through
Wednesday.

&&

.BEACHES...
Southerly swell (190 degrees) of 3 to 4 feet at 14-16 seconds will
generate elevated surf of 4-6 ft with sets to 7 ft along south
facing beaches through Sunday evening. In addition, strong rip and
longshore currents are expected at all beaches through Sunday. A
Beach Hazards Statement is in effect and contains more information.
Surf may remain elevated into early next week.

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement through this evening for Orange County
     Coastal Areas-San Diego County Coastal Areas.

     Extreme Heat Watch from Wednesday morning through Thursday
     evening for Coachella Valley-San Diego County Deserts.

PZ...None.

&&

$$

PUBLIC...Stewey
AVIATION/MARINE/BEACHES...CSP/Westerink