067
FXUS66 KSGX 160422
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
922 PM PDT Sat Jun 15 2024

.SYNOPSIS...
Areas of fog is possible along the coastal areas and far western
valleys tonight into Sunday morning. A cooling trend will occur
through Monday with gusty west winds across the mountains and
deserts each afternoon and evening. Slow warming will occur
Tuesday through next weekend as the West Coast trough weakens and
high pressure begins to expand into So Cal.

&&

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

Another hot day across the deserts, especially the lower deserts,
where highs hit anywhere from 110-116 degrees. In fact, Ocotillo
Wells tied with Blythe for the nation`s high with a high temp of
116 degrees, edging out Death Valley which had a high of 115.
Despite the intense heat, no daily temperatures were broken. Given
the cooling expect tomorrow, the Excessive Heat Warnings and Heat
Advisory were allowed to expire earlier this evening.

The 00Z KNKX sounding shows the marine inversion based near 1100
ft MSL. Given the approaching trough and the forecast development
of a weak coastal eddy, the marine layer should deepen slightly
overnight. Still expect fog along portions of the coast and onto
the coastal mesas tonight into Sunday morning, where fog could be
dense in spots.

The upper level trough amplifies Sunday as a weak short wave moves
through the mean flow, followed by a second stronger short wave on
Monday. This will bring considerable cooling especially for inland
areas on Sunday when high temps will be around 5-10 degrees lower
than today, followed by another 5 degrees or so of cooling for
Monday. By Monday, highs will be several degrees below seasonal
normals, back down to the low 80s in the valleys, upper 80s in
the high desert, and low 100s in the low desert. These waves will
also generate stronger onshore flow with breezy west winds with
gusts to around 35-50 mph in the mountains and deserts each
afternoon into late evening, strongest below the San Gorgonio Pass
and along I-8 near the Imperial County border. Minimum daytime
humidity of around 10-15 percent in the deserts will also lead to
elevated fire weather conditions each afternoon in the wind-prone
areas, including the Hesperia Fire.

Slow warming takes place Tuesday through Thursday as the trough
along the West Coast weakens, followed by more significant warming
Friday through next weekend as a broad upper level ridge of high
pressure over much of the eastern two-thirds of the country begins
to expand westward into CA. Nigh and morning low clouds will
continue across portions of the coasts and valleys through the
week. Both deterministic and ensemble guidance are hinting at the
potential for a easterly wave to move across Baja California next
weekend and monsoon moisture eventually being drawn up into So
Cal. The upper high isn`t in a favorable spot (ridge axis directly
overhead), so hard to say at this point if anything will come of
it other than perhaps some muggy weather in the lower deserts and
a few mid and high clouds.

&&

.AVIATION...
160335Z...Coast/Valleys...FEW010 with unrestricted VIS at this time.
Low clouds will increase in coverage and could spread 15-20 miles
inland by 13Z. Bases will start out around 1000 ft MSL, briefly
lower to near 700 ft MSL around 11Z then rise abv 1000 ft MSL by
15Z. CIG impacts most likely at coastal TAF sites 08Z-15Z with local
VIS 1-3 miles in fog on higher coastal terrain. Low clouds expected
to clear to the coast 7Z-20Z.

Mountains/Deserts...SKC with unrestricted VIS through Sunday. Areas
of wind gusts 25-35 kt from the west on the desert mountain slopes
and into the deserts through Sun, along with weak to MOD UDDFS.

&&

.MARINE...
Northwest winds may gust to around 20 knots at times in the outer
waters near San Clemente Island each afternoon and evening through
Monday. Otherwise, no hazardous marine conditions are expected
through Thursday.

&&

.BEACHES...
A combination of a west swell of around 5 feet/9 seconds in the
outer waters and south swells of around 2 feet/16 seconds on Monday
will bring surf of 3-6 feet along with a high rip current risk
through Monday. The surf and rip current risk will gradually lower
on Tuesday.

&&

.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 Monday evening for Orange County
     Coastal Areas-San Diego County Coastal Areas.

PZ...None.

&&

$$

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