958
FXUS66 KSGX 032036
AFDSGX

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

.SYNOPSIS...
Temperatures in the valleys, mountains and deserts will trend upward
this week as high pressure builds over the Great Basin. A shallow
marine layer will keep the coastal highs closer to their early June
averages.

&&

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

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. Thursday and Friday
will be the hottest days with High Desert highs from 97-103, and
Lower Desert highs will range from 108-113.

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...
032025Z...Coast/Valleys...SCT-BKN clouds with bases 1500-2300 FT MSL
will continue at the immediate coast this afternoon, with only
partial to intermittent clearing across much of the coast away from
southern San Diego County. Low clouds will push back inland after
00Z and locally inland overnight, but not entirely cover the coastal
basin by Tuesday morning. Tonight there is only a 20-30% chance of
CIGs occurring at KONT, and 10% or less for KSBD. Bases would be
1000-1500 feet MSL with more vis restrictions where clouds reach
inland overnight.

Mountains/Deserts...Local westerly wind gusts 25-35 kt after 21Z
through mountain passes, desert slopes and into adjacent deserts,
including through/near San Gorgonio Pass with MOD UDDFS.

Regionwide...SCT locally BKN high clouds above 20000 feet MSL today
and tonight.

&&

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


&&

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

&&

.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...Moede
AVIATION/MARINE...Adams