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000
FXUS66 KSGX 172025
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
125 PM PDT Wed Apr 17 2024

.SYNOPSIS...
Warm and dry days will continue through the period with minor day
to day changes in the weather expected. A weak shortwave trough
will bring subtle cooling over the next couple of days with a
deeper marine layer, where clouds and fog will expand in coverage
west of the mountains each night and morning, as well as windier
conditions across inland areas. High pressure will once again
build over the American Southwest and bring slightly warmer
temperatures and less wind by the weekend into early next week. A
trough will move into the area off the coast sometime by the
middle of next week, providing cooler and breezier weather for
SoCal.

&&

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

.SHORT TERM (Wednesday through Friday)...
A slow and steady period of marine laying mixing has occurred
through the day, with partial clearing across the beaches and
coastal waters. Clearing will continue slowly across Orange
County through the afternoon. As the ridge overhead breaks down
today with an approaching trough, the marine layer will deepen,
allowing for low clouds and fog to penetrate up to 10 miles inland
tonight and Thursday morning. Visibility will not be as low as it
is today, though some foggy conditions may occur on elevated
terrain. Winds will be fairly week across the mountains and
deserts today where areas will see winds 25-40 MPH.

Onshore flow will increase by Thursday, bringing subtle cooling to
the region and breezier conditions across inland areas. HREF shows
wind probabilities moderate to high in seeing wind gusts over 35
MPH across the mountains and deserts by Thursday afternoon and
evening, including places along Interstates 8 & 10 and Route 78
through the Anza Borrego Desert. Winds will be greatest and most
widespread on Friday afternoon and night, where these
probabilities increase. Friday will cool slightly further, though
temperatures will still be near to slightly above average.

&&

.LONG TERM (This Weekend into Next Week)...
The weak trough will be replaced by a building area of high
pressure off the coast into the desert southwest. This will relax
the pressure gradient field, leading to calmer winds across inland
areas. High temperatures will also increase as 850mb temperatures
exceed 20C, peaking on Sunday. We continue to watch the Coachella
Valley and Anza Borrego Desert to see if anyone will hit their
first triple digit temperature of the season. NBM probabilities
indicated a 40-60% chance of reaching this mark across the
Coachella Valley and a 25-45% chance across the Anza Borrego
Desert. GFS/ECMWF ensembles differ slightly in timing of the
departure of this ridge on Monday or Tuesday, but a trough
entering off the coast looks evident sometime by the middle of
next week, which will bring cooling to the region with breezier
conditions inland.

&&

.AVIATION...
171945Z...Coast...Patchy low clouds will linger over portions of the
coastal waters today with fog lingering near the coast as well. Low
clouds will redevelop over inland areas after 03Z tonight with more
expansive and uniform coverage overnight into Thursday. Bases should
be 700-1200 feet MSL with tops to 1600 feet. Low clouds should
scatter out by or shortly after 16z Thu.

Otherwise...mostly clear skies with unrestricted vis today, with
some increase in high clouds tonight.

&&

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

&&

.BEACHES...
A long-period swell (3 feet/17 seconds/200 deg) from the southern
hemisphere will build surf up to 6 feet today through Thursday,
especially on south-facing beaches. This will generate a high rip
current risk.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.

&&

$$

PUBLIC...APR
AVIATION/MARINE...Adams