735
FXUS66 KSGX 101219 CCA
AFDSGX

Area Forecast Discussion...CORRECTED
National Weather Service San Diego CA
519 AM PDT Fri Jul 10 2026

.SYNOPSIS...
A strong area of high pressure will continue to bring hot weather
through Friday. Ever so slight cooling occurs by the weekend into
Monday as high pressure moves to the northeast. The high
pressure`s movement will bring in greater monsoonal moisture for
our area by Sunday into at least the latter part of next week.
This will bring increased rain and thunderstorm chances to inland
areas with greater humidity for the entire region.

&&

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


...UPDATED AVIATION DISCUSSION...

Today through tomorrow night...

Currently, the marine layer is slowly expanding further eastward
into roughly around 5 miles inland for Orange and San Diego
counties, with bases generally between 500 to 1200 ft MSL. These
clouds will remain in place through the early morning hours, and
then should gradually dissipate fairly quickly for the inland areas,
as this layer is relatively thin. This should then further mix out
with clearing to the coastal areas by approximately 10 to 11 AM.

High pressure conditions continue to dominate the region. This will
translate to another warm day, with Extreme Heat Warning for the
lower deserts, and Heat Advisories in place for the Inland Empire
through today. There will be an influx of some mid-level monsoonal
moisture that will be moving in from the southeast during the
morning hours and throughout the day on Saturday. This will help to
slightly cool temperatures, especially over the deserts, due to the
increase of moisture. This may also result in a rouge shower or
storm developing over the mountains during the afternoon. There will
also likely be some castellanus clouds, and possible virga
(precipitation falling but not reaching the ground), or perhaps even
a few rain drops reaching the ground all the way to the coastal
areas from some of these clouds as they stream overhead throughout
the morning hours. This may also help to break up and disrupt the
marine layer, which will likely be similar in nature tomorrow night
as it was tonight.

Sunday through Thursday of next week...

By Sunday, a negatively tilted ridge over the entire western
region will stretch and expand back towards the west through the
mid part of next week. This will result in the production of
monsoonal waves to develop during the afternoon over the lower
deserts of Arizona, which will then propagate over southern
California as they move in from the east, and allow for chances of
afternoon showers and thunderstorms over the mountains and
deserts each afternoon through Thursday of next week. There could
even be a few of these waves propagating further enough westward
to bring a slight chance of showers/storms to the coastal areas as
well, although given the stability west of the mountains, these
will likely fall apart quickly as they do. This will also result
in increased humidity values, with more of that summer "mugginess"
feeling next week. There will also be increasing heat as a result
of the expanding ridge, with 596 dm heights overhead by Wednesday
and Thursday of next week. This will likely translate into the
need of heat products again, especially for the lower deserts and
Inland Empire. The influx of mid-level moisture may help to
mitigate these temperatures from getting as hot, but that is to be
determined in upcoming days in terms of the development of these
monsoonal waves.

&&

.AVIATION...
101200Z....Coast/Valleys...Cigs 700-1200 ft MSL widespread across
the coast and western valleys through this morning. Chances for cigs
below 1000 ft for coastal TAF sites is highest through 14Z at 80
percent. Vis restricted 1-5SM over higher coastal terrain. Scatter
out 16-18Z, but patchy low clouds to persist along immediate coast
into the afternoon. Low clouds around 1000-1500 feet MSL to move
ashore after 03Z Saturday and continue to fill into the inland
valleys throughout the rest of the forecast period (through 12Z),
with cigs slightly higher tomorrow evening.

.Mountains/Deserts...VFR conditions through the TAF period.

&&

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

&&

.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 Riverside County
     Mountains-San Bernardino County Mountains-San Bernardino
     and Riverside County Valleys-The Inland Empire-San Diego
     County Mountains.

     Extreme Heat Warning until 8 PM PDT this evening for Coachella
     Valley-San Diego County Deserts-San Gorgonio Pass near
     Banning.

PZ...None.

&&

$$

PUBLIC...Stewey
AVIATION/MARINE...Stewey

NWS San Diego (SGX) Office