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000
FXUS66 KSGX 241107
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
407 AM PDT Wed Apr 24 2024

.SYNOPSIS...
Gradually cooler through Thursday with a deep marine layer
persisting into Friday with patchy night and morning drizzle for
the coast and valleys. There will also be periods of gusty
southwest to west winds for the mountains and deserts into Friday
evening with the stronger gusts to 50 to 60 mph. Then drier with
warming, a shallower marine layer, and weaker winds for Saturday
through Monday with not much change for Tuesday.

&&

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

.SHORT TERM (Today through Friday)...
A low pressure system from the west will move inland across
southern California and northern Baja for late today and tonight.
This will be followed by a faster-moving low pressure system from
the northwest moving inland through southern California on Friday.

The marine layer is around 4000 to 4500 feet deep with coastal low
clouds extending inland across all of the valleys and onto the
coastal mountain slopes. Drizzle has been slower to develop than
on Monday night with less coverage of measurable amounts so far.
The greatest coverage has been for coastal areas of central San
Diego County inland into the adjacent western valleys.

The HREF shows greater coverage of light precipitation from
drizzle or light rain for late tonight into Thursday morning with
the greatest coverage across the coast and valleys in San Diego
County. Then patchier coverage for Thursday night into Friday
morning. High temperatures will continue to cool for inland areas
for today and Thursday with Friday a few degrees warmer for the
coast and valleys. With the cooling, high temperatures will be as
much as 10 to 15 degrees below average on Thursday for the
mountains.

There will continue to be stronger and gusty southwest to west
winds for the mountains and deserts into Friday evening with the
stronger winds each afternoon and evening. ECMWF ensemble output
and calibrated NBM wind guidance continues to show the strongest
gusts on Friday afternoon.

&&

.LONG TERM (Saturday through Tuesday)...
A warming trend for Saturday through Monday with not much change
on Tuesday with weak high pressure aloft. Winds will be weaker as
well. There are some model differences for Monday and Tuesday
which would impact the strength of the onshore flow and the depth
of the marine layer which is evident in the greater spread of the
high temperature forecasts for locations for the coast and
valleys versus the mountains and deserts. With the warming, high
temperatures would be a few degrees above or below average for
most locations on Sunday with high temperatures on Monday a few
to around 5 degrees above average.

&&

.AVIATION...
240930Z...Coast/Valleys/Foothills...Low clouds with bases 2000-2500
feet MSL and tops to 4000 feet will continue this morning. VIS 0-5SM
where clouds and terrain intersect, obscuring foothills. Expect
random and intermittent clearing 17-03Z, most likely 20-00Z.
Low clouds to fill the coastal basin again after 00Z with similar
bases, but tops rising to 6000 feet MSL early Thursday. -SHRA or -DZ
also possible after 06Z, lowering cigs and vis.

Mountains/Deserts...Mostly clear skies above 4000 feet MSL on
coastal slopes, with unrestricted VIS today and tonight.

&&

.MARINE...
No hazardous marine conditions are expected through Thursday night.
Stronger winds and choppy seas arrive Friday morning and continue
into Saturday morning, likely generating hazardous conditions,
especially in the outer waters.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory from 5 PM this afternoon to 11 PM PDT Friday for
     Apple and Lucerne Valleys-Coachella Valley-Riverside County
     Mountains-San Bernardino County Mountains-San Diego County
     Deserts-San Diego County Mountains-San Gorgonio Pass Near
     Banning.

PZ...None.

&&

$$

PUBLIC...17
AVIATION/MARINE...MM