699
FXUS66 KSGX 050346
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
846 PM PDT Thu Jul 4 2024

.SYNOPSIS...
Hot conditions will continue into at least the middle of next
week. The heat will peak on Friday and Saturday for most areas,
but above average temperatures will continue for all areas into
next week. The marine layer will continue to moderate temperatures
near the coast with night and morning coastal low clouds
extending into portions of the western valleys at times.

&&

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

Evening update...
Low clouds redeveloped at the beaches earlier this evening and are
beginning to spread a couple miles inland, elsewhere skies are
clear. Low-level moisture from the Gulf of California made it into
the lower deserts today with dew points at Palm Springs reaching
70 degrees this morning. This moisture didn`t completely mix out
as southeast flow prevailed there through the day, limiting
heating and keeping the high at Palm Springs at "only" 115
degrees. Local hi-res guidance shows another low-level moisture
surge late tonight into Friday morning, however, as the upper high
repositions itself low and mid level northeasterly flow should
usher in some drier air, allowing for more warming across the
entire region. With this in mind, did not do any further downward
adjustments for high temperatures tomorrow.

Previous discussion...
A strong ridge of high pressure will slowly move east setting up
over California`s Central Valley by Sunday. This will result in well
above average temperatures for inland areas this weekend. The upper
level ridge is expected to be it`s strongest Friday and Saturday,
which correlates with the peak of the heat for most areas at the
surface. The greatest warming on Friday is expected to be in the
inland valleys with a couple degrees of "cooling" for inland areas
Saturday. Moderate to major heat risk is expected Friday and
Saturday for inland Orange County, the valleys, and mountains.
The influence from the marine layer will continue to moderate
daytime temperatures along the coast.

Highs Friday are expected to be a few to 5 degrees warmer than today
in the deserts. An additional degree or two of warming is expected
on Saturday. Until the ridge becomes more settled over California,
there is a potential for morning gulf surges from the Gulf of
California to make it into the lower deserts. This could put a cap
on how high temperature readings get in the lower deserts Friday
through the weekend, but with the moisture increases will make it
feel more muggy. Current trend from the guidance is for a gradual
drying into early next week. If that drying trend verifies that
will allow for more daytime warming to actually occur each day,
with the potential for record breaking temperatures in the
deserts. Even if the daytime highs are capped by the moisture
surges, HeatRisk for the deserts will be major to extreme
Saturday and Sunday, continuing into next week.

Not quite as hot for the coast to the mountains for Sunday and
Monday with not much change for the deserts. There is a small chance
of at least a minor influx of monsoonal moisture into the area for
the latter half of next week. That would tend to bring warming
west of the mountains with high temperatures for the lower deserts
not quite as hot depending on the degree of moisture influx.
Current forecast follows the NBM closely for the middle to end of
next week with an uptick in temperatures for areas west of the
mountains Tuesday through Thursday and little change in
temperatures in the deserts. Chances of showers and thunderstorms
remain 10 percent or less through next Thursday.

&&

.AVIATION...
050330Z...Coast...Low clouds will gradually cover coastal areas
overnight, latest for Orange County. Bases will be 700-1000 feet
MSL, tops to 1500 feet, with reduced vis 2-5SM in BR over higher
coastal terrain 10-16Z. Scatter out Friday 15-17Z. Low clouds to
redevelop Friday evening after 03Z with similar bases/vis.

Otherwise, mostly clear skies with unrestricted VIS through Friday.

&&

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

&&

.BEACHES...
A long-period south swell will increase the surf, peaking late
Friday through Saturday, before subsiding Sunday. Sets of 6-7 feet
can be expected on south and southwest-facing beaches, especially in
Orange County. Check the Beach Hazards Statement for details.


&&

.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement through Sunday afternoon for Orange
     County Coastal Areas-San Diego County Coastal Areas.

     Excessive Heat Warning from 11 AM Friday to 9 PM PDT Saturday
     for Riverside County Mountains-San Bernardino County
     Mountains-San Bernardino and Riverside County Valleys-The
     Inland Empire-San Diego County Mountains-San Diego County
     Valleys.

     Heat Advisory from 11 AM Friday to 9 PM PDT Saturday for Orange
     County Inland Areas-Santa Ana Mountains and Foothills.

     Excessive Heat Warning until 9 PM PDT Wednesday for Apple and
     Lucerne Valleys-Coachella Valley-San Diego County Deserts-
     San Gorgonio Pass Near Banning.

PZ...None.

&&

$$

PUBLIC...SS/CO
AVIATION/MARINE...MM