556
FXUS66 KSGX 050318
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
818 PM PDT Fri Oct 4 2024

.SYNOPSIS...
Hot conditions are expected for inland areas through Monday.
Influence from the marine layer will help moderate temperatures
closer to the coast. The marine layer will become shallower over the
weekend, becoming more confined to coastal areas. A gradual cooling
trend is expected for much of next week, with temperatures returning
to near or slightly above average by the end of the week.

&&

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

.Evening Update...
Another day with record warmth inland, while clouds hugged the
beaches into the afternoon hours. Some areas, mostly in the
higher elevations, were able to break daily records by a couple
degrees today. It`s always fun to see the varying temperatures
across our area with conditions such as those from today.
Temperatures soared 40 degrees from this morning to afternoon in
sunny Ramona, while the temperature only went up one single degree
all day ~20 miles west at the shrouded beaches of Del Mar. Minor
forecast change this evening was to increase cloud coverage near
the beaches again on Saturday. High pressure will center over the
region tomorrow, pushing down the marine layer slightly further
than today. This will lead to a higher chance of foggy conditions
during the morning hours at the beaches with intermittent clearing
possible by the afternoon.

Subtle cooling trend continues to look likely by next week as a
weak trough moves in place of the ridge with temperatures still
above seasonal averages away from the coast. Confidence decreases
by later next week as model differences continue to be in
unfavorable agreement.

.Previous Discussion (150 PM Friday)...

As the ridge of high pressure builds back over Southern
California this weekend, the marine layer is expected to become
shallower and patchier, staying confined to coastal areas. With
the ridge aloft, any low clouds or fog develop at the coast and
beaches may have a difficult time clearing in the afternoons this
weekend.

For the weekend, the ridge of high pressure will shift back to the
west becoming more centered over Southern California. Highs on
Saturday are expected to be 3 to 7 degrees warmer than Friday west
of the mountains with minimal changes in the mountains and deserts.
A few additional degrees of warming is expected for most locations
Sunday with no change in high temperatures mainly for the mountains
and High Desert. Highs will be mostly 15 to 20 degrees above average
Saturday and Sunday except for the highest elevations in the
mountains and along the coast. Low temperatures across the inland
areas will remain above average. A shallower marine layer is
expected over the weekend, which will allow for some warming closer
to the coast. Along the coast, highs will be 3 to 7, locally up to
10 degrees above average.

A trough of low pressure is forecast to develop near the California
coast early next week. Influence from the trough will bring a few
degrees of cooling for most locations Monday, with continued cooling
into Friday. There still remains some uncertainty surrounding the
strength of the low through Thursday with uncertainty in the
position of the low starting Wednesday. The strength and position of
the low will ultimately impact how much cooling occurs. Current
forecast has high temperatures gradually decreasing each day into
Friday. For the end of the week near to slightly above normal
temperatures are expected the coastal areas with temperatures 5 to 7
degrees above average for the valleys, mountains, and deserts. The
increase in onshore flow from the trough will allow night and
morning coastal low clouds to increase in coverage and spread
farther inland, returning to the western valleys for the middle to
end of next week.

&&

.AVIATION...050300Z...Coast and Western Valleys...Low clouds have
begun filtering back into inland areas this evening, and will push
10-15 mi inland overnight. Bases are currently 600-1000 ft MSL, but
these will lower to 400-700 ft MSL overnight, with tops to 900-1200
ft MSL. Vis reductions in BR to 0-5 SM expected for most of the
coastal sites overnight, with greater vis reductions 0-3 SM for
higher coastal terrain and in western valleys where clouds intersect
with terrain. Clouds and fog scattering to the beaches 16-18Z, but
only intermittent clearing at the immediate beaches into the
afternoon, especially in northern San Diego County. Low clouds
redevelop and move inland again 02-05Z Sun, with lower bases 200-600
ft MSL.

Coastal Mountain Foothills/Mountains/Deserts...SCT to locally BKN
clouds 12000-15000 feet MSL, mostly over the mountains, 17Z Sat to
01Z Sun. Otherwise, mostly clear skies with unrestricted VIS
expected through Saturday evening.

&&

.MARINE...Areas of patchy fog around 1-3 SM possible tonight into
Saturday morning. Higher confidence in dense fog along the nearshore
waters for late Saturday into Sunday morning. Otherwise, no
hazardous marine conditions are expected through Wednesday.

&&

.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...APR/CO
AVIATION/MARINE...CSP