073
FXUS66 KSGX 040357
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
857 PM PDT Mon Jun 3 2024

.SYNOPSIS...
Warming conditions in the valleys, mountains, and deserts for the
middle to end of this week. A shallow marine layer will keep night
and morning low clouds and fog close to the coast. Additionally, the
marine layer influence will keep highs at the coast closer to their
seasonal average.

&&

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

A swath of high clouds are moving south across Southern California
tonight. Areas of high clouds are expected to linger into Tuesday
afternoon. High temperatures on Tuesday are expected to be a few
degrees warmer than today at the coast and in the High Desert; 4 to
7 degrees warmer than today in the valleys and mountains; and about
the same as today in the low deserts. Conditions will continue to
warm for most inland locations through Friday. Moderate heat risk is
expected in the Inland Empire and in the mountains with areas of
major heat risk for the deserts. This level of heat will affect
individuals sensitive to heat and those without access to effective
cooling systems. Make sure to stay hydrated and avoid being outdoors
in the sun between 10 AM - 5 PM if possible.

From Previous Discussion...

A weak upper trough will drift across California tonight, followed
by a Great Basin ridge that will bring warmer/hotter days Wednesday
through Friday. Model trends show the ridge exerting a greater
influence over the Southwest than previous runs, mainly because the
closed upper low that was forecast to be over northern Baja this
week is now projected to be farther southwest off the coast of
southern Baja. Therefore, the heat influence will be greater over
Southwest California, and an Excessive Heat Watch has been issued
for all the desert zones (High Deserts, Coachella Valley, the San
Diego County Deserts) Wednesday through Friday. Highs in the High
Desert will range from 97-103 degrees, and in the Lower Desert highs
will range from 108-113 degrees.

Elsewhere, mountain highs will be from 80-90. The valleys will also
be warmer as the ridge aloft squashes the marine layer a few hundred
feet. Inland Empire highs will range from 93-97 in the eastern
sections and from 85-93 in the western sections. Areas within 10
miles of the coast will remain under the influence of the marine
layer which will keep highs coastal highs in the upper 60s at the
beaches but from 75-80 degrees from 5 to 10 miles inland.

Next weekend the long range models show the southern Baja closed low
moving north. The ECMWF transitions this closed low to a weaker open
wave, while the GFS maintains the closed low and shows a greater
chance of isolated convection. These probabilities will become
clearer over the coming days. The weekend will trend cooler as
heights lower ahead of the approaching trough. There should also be
some deepening of the marine layer.

&&

.AVIATION...
040330Z...Coast/Valleys...Low clouds with bases 1500-2000 FT MSL
will continue to fill in across the coast/valleys tonight, with
lower cigs of 1000-1500 FT MSL possible 06z-15z Tue. Reduced vis
where low clouds and terrain intersect. There is a 10% chance of
cigs VCTY KONT/KSBD 12z-15z Tue. Scatter out across the valleys 16z-
19z Tue, with only partial clearing at the coast.

Otherwise...SCT-BKN AOA 20,000 FT MSL through Tue.

&&

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

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Excessive Heat Watch from Wednesday morning through Friday
     evening for Apple and Lucerne Valleys-Coachella Valley-San
     Diego County Deserts-San Gorgonio Pass Near Banning.

PZ...None.

&&

$$

PUBLIC...CO/Moede
AVIATION/MARINE...EA