Etiwanda, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

875
FXUS66 KSGX 130822
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
122 AM PDT Sun Jul 13 2025

.SYNOPSIS...
A little warmer inland for today and Monday. Gradual cooling back
to near seasonal averages expected for the middle to the end of
the week. While chances are still low and uncertainty remains,
confidence is increasing for the potential of monsoonal
thunderstorms over the mountains late in the week. Marine layer
low clouds and patchy fog will spread across the coastal areas
and into the western valleys during the nights and mornings.

&&

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

This morning...The marine layer is about the same depth as at this
time yesterday and the low clouds are similar in coverage.
Clearing may be a little faster today than yesterday as the marine
layer inversion seems to be a little weaker.

The dominant ridge will remain centered about 135 miles west
southwest of San Diego through Monday. This will allow inland
temperatures to rise by a few degrees above what they were the
last couple of days. Temperatures in the mtns and deserts will be
several degrees above seasonal averages while west of the mtns,
temperatures will be near or a few degrees below seasonal
averages. This is mostly due to a relatively shallow but
persistent marine layer, with low clouds and patchy fog in the
coastal areas and western portions of the inland valleys each
night and morning. On Monday, a couple of inverted troughs in the
southeast flow on the southern side of the east-west oriented
ridge axis will bring some monsoonal moisture into SoCal but the
threat of afternoon convection will be low because the moisture
will be limited and mostly above 10,000 ft, although a stray
shower or tstm can`t be ruled out altogether.

For Tuesday through the end of the week, model solutions begin to
diverge significantly introducing more uncertainty into the
forecast but in general, the dominant high pressure ridge will be
weakened and displaced eastward towards the Four Corners as a low
pressure system moves inland over the Pacific Northwest. During
this time, temperatures will begin to trend generally lower even
as conditions become drier for Tue and Wed. For Thursday through
the weekend, an increasing number of solutions across model
platforms are indicating an increase in monsoonal moisture with a
corresponding increase in the chances for afternoon showers and
tstms, mainly in the mountains. This change in the pattern will
likely continue the trend toward lower temperatures for the mtns
and deserts.

&&

.AVIATION...
130900Z....Coast/Valleys/Foothills...Low clouds based 1100-1500ft
MSL have reached into western valleys and will reach up to 20 miles
by 11z. Localized VIS reductions for valleys and terrain down to 3-
5SM. CIG expected at KONT and much of the Inland Empire after 10z
with bases closer to 700-900ft MSL. Clouds clear to the coast by 16-
18z, possibly lingering at the beaches through the afternoon. Clouds
develop and push in again late Sun after 02z with bases closer to
1500ft MSL.

.Mountains/Deserts...VFR conditions and unrestricted VIS through
Monday.

&&

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

&&

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

&&

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

&&

$$

PUBLIC...PG
AVIATION/MARINE...Westerink