369
FXUS66 KSGX 170014
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
514 PM PDT Thu Jul 16 2026

.SYNOPSIS...
One last day of heat alerts with temperatures cooling near average
by Friday into much of next week. Increasing monsoonal moisture will
move into the region through Friday, with elevated chances over the
mountains and locally into the deserts. Moisture decreases by the
weekend into the first half of next week with minor chances over the
mountain ridges, increasing again by late next week.

&&

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


...UPDATED AVIATION DISCUSSION...

Showers and weak thunderstorms are seen moving from NE to SW over
Arizona and SE California. Some of these showers may reach the lower
deserts by the early afternoon. Increased moisture and instability
is seen in our sounding from this morning, aiding in a better set up
for storms to pop over the mountains. Rain rates may near one half
inch in some cells along the mountain desert slopes. A similar
environment is seen on Friday, with elevated chances over the
mountains and locally into the deserts. Pressure heights will fall
by Friday into the weekend, providing slight cooling with high and
low temperatures closer to average. The marine layer will be
patchier with clouds forming near the coast nights and mornings,
with better clearing each afternoon.

High pressure becomes centered over the Rockies and Central Plains,
pivoting monsoonal moisture further to the east this weekend.
This will lead to minimal chances for precipitation over the
mountains during this time into the first half of next week. The
pattern stays fairly similar through Tuesday, keeping temperatures
closer to average with a healthy marine layer near the coast and
far western valleys each night.

Models show a subtle increase in moisture by next Wednesday,
potentially into the latter half of next week. Looking beyond this,
models show a bit of spread on the monsoonal moisture feed. The
major factor will be where the area of high pressure will be placed.
Some models have this further east into the Southern Plains, which
would shunt moisture further out of our region, or closer to the
Central Rockies, which would favor a greater moisture set up. NBM
shows high temperatures sticking near average with 80s and 90s for
many areas below 6000 feet with warmer/cooler temperatures for the
lower deserts and along the coastal areas.

&&

.AVIATION...
170015Z....Coast/Valleys...VFR prevails through this
evening with periods of FEW-SCT high clouds AOA 15,000ft MSL.
Expecting initially patchy low clouds based 700-1000 ft MSL to push
back into coastal areas after 06z Fri. Confidence in coverage is
relatively low (especially for Orange County) as mid-level monsoonal
moisture/clouds move in overnight, which may limit the coverage of
the marine layer clouds. Patchy minor vis reductions (2-5SM)
expected along elevated coastal terrain. Any low clouds will clear
to the coast by 16-17z with southerly breezes expected near the
coastline Friday afternoon.

.Mountains/Deserts...Periods of high clouds AOA 15,000 ft and VFR
conditions expected throughout the period. TSRA has mostly ended
this evening, though cannot rule out another cell or two over San
Diego/Riverside Co mtns through 02z. SCT Cu based 10-12 kft and ISO-
SCT SHRA/TSRA redevelop over the mtns Friday afternoon. Any storms
that develop may produce lightning, gusty winds, and vis reductions.

&&

.MARINE...
No hazardous marine conditions are expected through Monday.

&&

.BEACHES...
High amplitude southerly swell (4-5 ft with a period of 12-13
seconds) will build Saturday into Sunday, bringing elevated surf and
strong rip and longshore currents for Sunday into early next week.
Highest surf (up to 7-8 ft) will be along south and southwest-facing
beaches.

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory until 8 PM PDT this evening for Orange County
     Coastal Areas-San Diego County Coastal Areas.

     Extreme Heat Warning until 8 PM PDT this evening for Coachella
     Valley-Orange County Inland Areas-Riverside County
     Mountains-San Bernardino County Mountains-San Bernardino
     and Riverside County Valleys-The Inland Empire-San Diego
     County Deserts-San Diego County Mountains-San Diego County
     Valleys-San Gorgonio Pass near Banning-Santa Ana Mountains
     and Foothills.

PZ...None.

&&

$$

PUBLIC...APR
AVIATION/MARINE/BEACHES...KW

NWS San Diego (SGX) Office