968
FXUS66 KSGX 201138
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
438 AM PDT Thu Jun 20 2024

.SYNOPSIS...
The warming trend will continue through Saturday with high
temperatures on Saturday as much as 5 to 10 degrees above average.
A shallow intrusion of lower level moisture for the lower deserts
will bring warmer nights with days not quite as hot for the
weekend. There is also a slight chance of showers and
thunderstorms, mainly for the mountains and deserts, for Saturday
afternoon and again on Sunday. Then a little drier and continued
hot inland for Monday through Wednesday. The marine layer will
continue to keep areas near the coast cooler. Night and morning
coastal low clouds will continue to spread into portions of the
valleys late each night, but may be a little patchier over the
weekend.

&&

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

.SHORT TERM (Today through Saturday)...
The trough of low pressure near the California coast will weaken
as high pressure across the south central states expands across
the southwest states. The warming trend will continue into the
weekend. Saturday is expected to be the hottest day of the weekend
for most areas with a Heat Advisory for the valleys, inland Orange
County, and the mountains below 5000 feet for Saturday, and
continuing for Sunday for the Inland Empire and inland Orange
County.

A shallow intrusion of lower level moisture into the lower deserts
on Saturday morning could limit any additional warming on
Saturday with high temperatures a degree to two lower than on
Friday. There could be some clouds over the mountains on Saturday
afternoon with a slight chance of showers and thunderstorms.

The marine layer will remain around 2000 to 2500 feet deep with
night and morning low clouds spreading into portions of the
valleys late each night. The coverage may be a little patchier for
Friday night into Saturday morning.

&&

.LONG TERM (Sunday through Wednesday)...
NBM continues to show a slightly greater, though shallow,
intrusion of lower level moisture on Sunday morning with a slight
chance of showers and thunderstorms on Sunday for the mountains,
deserts, and inland valleys.

Nights will be warmer for the lower deserts for the weekend into
early next week with the modest increase in moisture and high
temperatures will warm a few degrees for the middle of next week
as the weekend moisture slowly decreases for the early and middle
part of next week.

There is an Excessive Heat Watch for the San Diego County deserts
beginning Saturday and continuing into next week and for the
Coachella Valley for Tuesday and Wednesday of next week. With
elevations in the San Diego County deserts a few hundred feet
higher than the valley floor in the Coachella Valley, there should
be less moderating impact on high temperatures for the San Diego
County deserts over the weekend from shallow influxes of lower
level moisture.

&&

.AVIATION...
200845Z...Coast/Valleys...Areas of low clouds with bases 1300-1500
ft MSL and tops to 2000 ft MSL will continue to spread around 20-25
miles this morning. There is a 50% chance that KONT between 12Z-15Z.
Local VIS 3-5 SM in BR/FG where clouds near terrain in the valleys,
including VCNTY KRNM. Valleys clearing 14Z-16Z, with coastal areas
clearing 16Z-19Z. Areas of low clouds will develop again this
evening with bases around 700-1000 ft MSL and tops to 1500 ft MSL,
spreading 10-15 mi inland tonight into Fri morning.

Mountains/Deserts...Mostly clear with unrestricted VIS will continue
through Thu evening. West winds with gusts 20-30 kt through San
Gorgonio Pass and on the desert slopes this afternoon and evening.

&&

.MARINE...
No hazardous marine weather conditions are expected through Monday.

&&

.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 Saturday to 8 PM PDT Sunday for Orange
     County Inland Areas-San Bernardino and Riverside County
     Valleys-The Inland Empire.

     Heat Advisory from 10 AM to 8 PM PDT Saturday for Riverside
     County Mountains-San Bernardino County Mountains-San Diego
     County Mountains-San Diego County Valleys.

     Excessive Heat Watch from Tuesday morning through Wednesday
     evening for Coachella Valley.

     Excessive Heat Watch from Saturday morning through Thursday
     evening for San Diego County Deserts.

PZ...None.

&&

$$

PUBLIC...17
AVIATION/MARINE...SS