814
FXUS66 KSGX 050400
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
900 PM PDT Tue Jun 4 2024

.SYNOPSIS...
Hot conditions expected Wednesday through Friday for inland
locations. The marine layer will become shallower with night and
morning low clouds more confined to the coast and portions of the
western valleys, keeping temperatures there closer to the
seasonal average. A gradual cooling is expected for the weekend
into early next week.


&&

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

Satellite imagery from 9 PM is showing low clouds along the San
Diego County coast, slowly moving north into Orange County. The
inversion on the 00Z sounding from NKX tonight was about 500 ft
lower than on the 00Z sounding yesterday. The marine layer will
continue to get shallower as high pressure builds over the Western
US. This will keep marine layer low clouds and fog confined to
areas closer to the coast and in the western valleys each night
and morning. Even with a shallower marine layer, complete
clearing at the coast remains in question with the inversion
expected to strengthen into Thursday and Friday as the ridge peaks
in strength.

With the heat Wednesday through Friday, moderate heat risk is
expected in the Inland Empire and portions of the mountains with
areas of major heat risk expected in the deserts. Make sure to
stay hydrated and reduce exposure to heat if you can.

From Previous Discussion...

High pressure aloft over the Western US will continue the warming
trend through Thursday for most inland areas. The warmest days for
areas west of the mountains and the High Desert generally look to be
Wednesday and Thursday, while the lower deserts see peak heat occur
on Thursday and Friday. Widespread highs between 100 and 105 for the
High Deserts and highs of 108 to 113 for the lower deserts will
occur during their respective hottest days. The Inland Empire will
see highs routinely in the middle 80s to middle 90s, locally into
the upper 90s. While these temperatures are warmer than seasonal
averages for early June, very few, if any daily temperature
records look to be challenged. The coasts will remain relatively
cool through this week owing to marine layer clouds each morning.

The high pressure aloft then looks to weaken and give way to upper
level troughing later this weekend and early next week. Upper
troughing does look to draw in the remnants of an upper low
over/near the southern Baja California coast, but overall impacts to
sensible weather look to be minor, perhaps some extra high clouds
owing to a lack of deep-layer moisture. The ultimate impacts look to
be a gradual cooling trend and a re-deepening of the marine layer.
Highs will still be rather hot in the deserts, generally 105 to 110
in the lower deserts and the middle to upper 90s for the high
deserts. Marine layer clouds will gradually become more expansive
again during this time. And begin to spread back in and cover all of
the coastal basin again by early next week.

&&

.AVIATION...
050300Z...Coast/Valleys...BKN-OVC010-015 tops 020 spread into
valleys through 14Z Wednesday. Clearing in the valleys 16Z-19Z
Wednesday but only partial and brief clearing at the coast 20Z-24Z.

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

&&

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

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory from 10 AM Wednesday to 9 PM PDT Friday for San
     Bernardino and Riverside County Valleys-The Inland Empire.

     Excessive Heat Warning from 10 AM Wednesday to 9 PM PDT Friday
     for Apple and Lucerne Valleys-Coachella Valley-San Diego
     County Deserts-San Gorgonio Pass Near Banning.

PZ...None.

&&

$$

PUBLIC...CO/Adams
AVIATION/MARINE...Moede