561
FXUS66 KSGX 080547
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
1047 PM PDT Mon Sep 7 2026

.SYNOPSIS...
Scattered light rain possible through the afternoon. An isolated
thunderstorm or two cannot be ruled out today. Hot conditions
expected for the middle to end of the work week, resulting in areas
of moderate to major HeatRisk. Slight chance of mountain showers and
thunderstorms Tuesday and Wednesday. Gradual cooling for the
weekend.

&&

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

...UPDATED AVIATION DISCUSSION...

High cloud coverage continues, but is expected to thin out Tuesday.
Precipitable water values are expected to remain elevated which
will keep overnight lows elevated and conditions feeling tropical.
The tropical feeling airmass is expected to disrupt marine layer
low cloud and fog development and may result in a weaker afternoon
sea breeze. This will contribute to high and low temperatures
along the coast running 10 to 15 degrees above average. Further
inland, daytime highs will be 5 to 10 degrees above average with a
more notable increase in low temperatures which are expectd to
run 8 to 15 degrees above average. Hottest conditions are expected
Tuesday through Thursday for the coast, valleys, and mountains
below 5000 ft with hottest conditions expected in the low desert
Wednesday through Friday. Widespread moderate to areas of major
HeatRisk are expected.

The lingering moisture and increased sunshine for Tuesday and
Wednesday will increase chances of afternoon showers and
thunderstorms over the mountains. There is expected to be little to
no additional forcing outside of the usual diurnal heating so
coverage of any thunderstorms should be fairly isolated. By
Thursday, a transient ridge of high pressure is expected to move
directly over Southern California. This would result in an airmass
likely too stable for thunderstorm development, although with
lingering moisture in the air a few showers cannot be ruled out over
the mountains.

There is a spread in potential outcomes for the upper level pattern
over the upcoming weekend. 32 percent of ensemble solutions have a
trough over the Pacific Northwest, which would bring noticeable
relief from the heat and humidity. 17 percent of solutions keep the
ridge overhead which would prolong the heat event. The rest of the
solutions are somewhere in between, with a slower passage of the
trough but a weakening of the ridge. Current forecast follows the
NBM and is more inline with the "in between" solutions with a
gradual decrease in both high and low temperatures Friday through
Sunday.

&&

.AVIATION...
080530Z...VFR conditions expected across the region through Tuesday
with SCT-BKN clouds around 10-20 kft continuing. ISO -SHRA/TSRA over
mountains 19-01Z. Localized gusty winds in and near any TSRA.

&&

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

&&

.BEACHES...
A large south swell from Tropical Storm Marie will continue to
produce large surf of 4 to 6 feet, with sets up to 8 feet tonight,
highest on south and southwest facing beaches. This will result in
strong rip and longshore currents, creating hazardous swimming
conditions. Additionally, high tides during the evenings will
combine with the high surf to produce minor tidal overflow, coastal
flooding, and localized beach erosion. Swell and surf will gradually
diminish tonight through Tuesday. Check the Coastal Hazard Message
for details.

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Coastal Flood Advisory until 11 PM PDT Tuesday for Orange County
     Coastal Areas-San Diego County Coastal Areas.

     High Surf Advisory until 11 PM PDT Tuesday for Orange County
     Coastal Areas-San Diego County Coastal Areas.

     Heat Advisory from 10 AM Tuesday to 8 PM PDT Thursday for Orange
     County Coastal Areas-Orange County Inland Areas-Riverside
     County Mountains-San Bernardino and Riverside County
     Valleys-The Inland Empire-San Diego County Coastal Areas-
     San Diego County Mountains-San Diego County Valleys-Santa
     Ana Mountains and Foothills.

     Extreme Heat Warning from 10 AM Wednesday to 8 PM PDT Friday for
     Coachella Valley-San Diego County Deserts-San Gorgonio Pass
     near Banning.

PZ...None.

&&

$$

PUBLIC...CO
AVIATION/MARINE/BEACHES...MM




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