128
FXUS66 KSGX 031151
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
451 AM PDT Mon Jun 3 2024

.SYNOPSIS...
High pressure aloft over California will bring a strong warming
trend for early this week for inland areas with the heat peaking
Wednesday through Friday with high temperatures for the deserts as
much as 10 to 15 degrees above average. This will be followed by
gradual cooling for Saturday through Monday with high temperatures
for inland areas cooling a few degrees each day. The marine layer
will moderate the heat toward the coast with the marine layer
mostly 2000 to 2500 feet deep, possibly a little shallower for
Wednesday through Friday with night and morning coastal low clouds
not spreading as far into the valleys.

&&

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

.SHORT TERM (Monday through Wednesday)...
High pressure aloft will strengthen over California early this
week bringing a strong warming trend for inland areas. The marine
layer and weak onshore flow will moderate the heat toward the
coast with the greater warming for the mountains, valleys, and
deserts. The marine layer will become a little shallower each day
with night and morning coastal low clouds not spreading as far
into the inland valleys each night.

&&

.LONG TERM (Thursday through Sunday)...
The heat for inland areas is expected to peak on Wednesday
through Friday with the heat for the lower deserts peaking on
Thursday and Friday. Later shifts should consider expanding the
Excessive Heat Watch to include the lower deserts for Thursday and
Friday as the currently forecast heat risk would justify an
Excessive Heat Warning for portions of the lower deserts.
Consideration should also be given to expanding the Excessive Heat
Watch for the Apple and Lucerne Valleys for Wednesday and
Thursday to also include Friday as the more inland portions still
have heat risk sufficient for an Excessive Heat Warning on Friday.

The marine layer will moderate the heat toward the coast with
high temperatures for areas near the coast warming around 5
degrees from Sunday through Thursday with the mountains, valleys,
and deserts warming around 15 to 20 degrees.

After Friday, there should be a gradual cooling trend for inland
areas as high pressure aloft weakens with high temperatures a few
degrees cooler for inland areas each day for Saturday through
Monday. The marine layer will be a little shallower for Wednesday
through Friday with night and morning coastal low clouds not
spreading as far into the valleys. This should be followed by slow
deepening of the marine layer for Saturday through Monday with
night and morning coastal low clouds spreading a little farther
into the valleys each night.

Even with the warming, it is going to be difficult to break the
existing high temperature records. The current forecast of 112 for
Borrego Springs on Friday would tie the existing record set in
2013. There is greater potential to tie or break the existing
record warm minimum temperatures on Thursday and Friday for
portions of the mountains and lower deserts.

&&

.AVIATION...
030930Z...Coast/Valleys...Low clouds will cover the entire coastal
basin with bases 1500-2000 feet MSL with tops to 2800 feet this
morning. Some higher terrain will be obscured in clouds/FG, with
local VIS 3-5SM in the valleys. Scattering and clearing will occur
16-19Z in the valleys and 18-20Z near the coast, with areas of BKN
clouds continuing at the immediate coast this afternoon. Low clouds
will push ashore after 00Z and locally inland overnight, but not
entirely cover the coastal basin by Tuesday morning. 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.

&&

.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 Thursday
     evening for Apple and Lucerne Valleys.

PZ...None.

&&

$$

PUBLIC...17
AVIATION/MARINE...MM