747
FXUS66 KSGX 272047
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
147 PM PDT Thu Jun 27 2024

.SYNOPSIS...
Slightly cooler weather is expected the next couple of nights
before a slow warming trend occurs into early next week. The
marine layer will be deep enough to allow night and morning clouds
for coasts and adjacent valleys west of the mountains. High
pressure will move into the area by Sunday into early next week,
where highs will be near 5 degrees to locally 10 degrees above
average. Triple digit will be felt from the deserts into portions
of the Inland Empire. This heat may last into much of next week as
high pressure off the coast moves into the area.

&&

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

Mostly clear skies were seen over SoCal this afternoon. Low clouds
off the coast will begin to reform this evening and cover most
areas within 20 miles of the coast tonight. The marine layer will
be relatively unchanged in depth over the next couple of days.
Friday will be a degree or two cooler as a trough tries to
maintain a zonal pattern. West winds will continue to be breezy
across the mountains and deserts today into tomorrow. This looks
to be short-lived as the high across the desert southwest slowly
expands more toward the west by the weekend. This expansion will
increase our overall moisture profile, but not enough for storm
chances for inland locations, though these areas will see more
humidity.

Pressure heights will continue to rise Sunday into Monday. Chances
for 115 degree readings across the lower deserts increase to
around 30-60 percent by this time per NBM. By Sunday, increased
heat risk will not only be across the deserts but also most areas
away from the coast. Highs in the near or above 100 degrees are
likely for portions of the Inland Empire, with highs in the 90s
across southern mountain areas and SD/OC valleys.

Global ensembles are generally in agreement about high pressure
building into area off the coast by the middle of next week, near
569-600 dm. This would continue the very warm conditions for much
of the week for areas away from the coast. If this does occur,
temperatures will continue to be 5 to locally 10 degrees above
average. Confidence is moderate to high that temperatures will
fluctuate minimally from day to day with warmer overnight low
temperatures as we near the 4th of July holiday.

&&

.AVIATION... 270840Z...Coast/Valleys...Marine later has retreated
offshore this afternoon, with otherwise clear skies. Clouds
redeveloping near the coast 00-03Z tonight and spreading
northwards and inland tonight into Fri morning with similar
bases/tops as last night/this morning. Inland extent will also be
similar to slightly farther east. Marine layer retreating out of
inland valleys 14-16Z and coastal area cigs mostly clearing
16-18Z. Otherwise mostly clear with unrestricted vis through Fri
morning.

Mountains/Deserts...West winds starting to pick up this afternoon,
with sfc gusts 25-35 kt across portions of the mountains and deserts
into the evening. Locally stronger gusts to 45 kt through the San
Gorgonio Pass. Mod up/downdrafts over and east of the mountains.
Winds diminishing early Friday morning, then picking up again to
similar strength late Fri afternoon. Otherwise a few isolated Cu
have developed over mountain crests and a few more possible this
afternoon, all of which will dissipate quickly towards sunset, and
unrestricted vis.

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Excessive Heat Warning until 8 PM PDT this evening for Coachella
     Valley-San Diego County Deserts-San Gorgonio Pass Near
     Banning.

PZ...None.

&&

$$

PUBLIC...APR
AVIATION/MARINE...CSP