943
FXUS66 KSGX 060939
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
239 AM PDT Sun Oct 6 2024

.SYNOPSIS...
Hot conditions for inland areas will continue through much of this
week. Overall, today will be the hottest day with gradually lower
temperatures into next weekend. Inland temperatures will remain
above seasonal averages and next Saturday looks like it will be
the coolest day but even then, temperatures will still be as much
as 6 degrees above seasonal averages in the mountains and deserts.
The shallow marine layer continues to moderate temperatures near
the coast where it will remain near or slightly above seasonal
averages. On Tuesday, the marine layer deepens significantly and
spreads cooler marine air farther inland, beginning a trend of
gradually lower temperatures for all areas.

&&

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

This morning, the marine layer is marginally shallower than
yesterday but still the low clouds and fog have spread up to 15
miles inland in some areas. Areas of fog with reduced visibility
is affecting elevated coastal terrain. A clearing pattern and
timetable similar to yesterday is likely, with low clouds and fog
clinging to the beaches into the afternoon.

The dominant upper high is now centered over the lower Colorado
River valley with ridging covering all of the Inter-Mountain West.
Today looks like it will be the hottest day, mainly for inland
areas where temps will be 10-20 degrees above seasonal averages.
High temps in the inland valleys will range from the mid 90s to
about 103, the mtns below 6000 ft will be in the 80s to 90s, the
upper deserts will be in the 90s to low triple digits and the
lower deserts will be 105-113 degrees.

Relatively weak upper level troughing to the west will gradually
move inland over SoCal as a more intense trough moves inland over
the Pacific Northwest. The ridge will weaken and be displaced to
the east. Tuesday will be noticeably cooler for much of the region
as the upper trough moves overhead, deepening the marine and
spreading night and morning low clouds and fog farther inland.
Even areas too far inland to be influenced by the marine layer
will experience some cooling as heights and thickness decrease.
Even so, temperatures will remain 10-15 degrees above average in
the valleys, mtns and deserts. The cooling trend continues into
next weekend, and Saturday will likely be the coolest day overall.
However, inland temperatures will still be as much as 6 degrees
above average.

Temperatures look like they will trend upward again for next
Sunday as the high pressure ridge begins to rebound but the
forecast is quite uncertain at this time due to the spread in
ensemble member solutions across model platforms.

&&

.AVIATION...
060845Z...Coasts/Valleys...Stratus with bases 400-800 ft MSL and
tops to 1100 MSL continuing along the coast and up to 10-15 mi
inland this morning. Areas of 2-4 SM vis in BR/HZ, locally as low as
1/4 SM in FG on the coastal mesas and where stratus nears terrain in
the western valleys. Clouds and vis restrictions clearing over land
areas 15-18Z, though there is a 50-60% chance that CIGS/reduced vis
will continue along the immediate coast through the afternoon,
especially in San Diego County. Stratus will begin to spread 5-10 mi
inland after 07/02Z. Bases will closer to 300-600 ft MSL with
widespread vis below 3 SM tonight into Monday morning.

Mountains/Deserts...SCT cumulus with bases 12,000-15,000 feet MSL
over the mountain crests likely again 18-01Z this afternoon.
Otherwise, mostly clear skies with unrestricted VIS expected through
Monday morning.

&&

.MARINE...
Fog with visibility 1-3 nm along the nearshore waters persisting
through late this morning and again tonight into late Monday
morning. Otherwise, no hazardous marine conditions are expected
through Thursday.

&&

.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 Monday for Coachella
     Valley-San Bernardino and Riverside County Valleys-The
     Inland Empire-San Diego County Deserts-San Diego County
     Valleys-San Gorgonio Pass Near Banning-Santa Ana Mountains
     and Foothills.

     Heat Advisory until 8 PM PDT Monday for Riverside County
     Mountains-San Bernardino County Mountains-San Diego County
     Mountains.

PZ...None.

&&

$$

PUBLIC...PG
AVIATION/MARINE...SS