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217
FXUS66 KSGX 101628
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
928 AM PDT Fri May 10 2024

.SYNOPSIS...
There is a slight chance of showers over the San Bernardino and
Riverside County mountains this afternoon and evening. Areas of
night and morning low clouds and fog will continue across portions
of the coastal areas and valleys through the week. Gradual
warming inland through Sunday followed by minor cooling Monday and
Tuesday. Inland warming trend will resume on Wednesday.

&&

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

Low clouds eventually filled nearly the entire coastal basin by
sunrise, even though San Diego County was late to the cloud party.
The Inland Empire and Orange County have started to clear pretty
effectively already. There may be some intermittent cloudiness
near the coast in San Diego County this afternoon, but you can
count on mostly sunny skies for most areas later today. A weak
upper level trough sits over the West today and Saturday. Today
there is also a wave of mid level moisture and instability that
will bring some clouds to the mountains and deserts, and isolated
showers to the higher mountains this afternoon and evening. The
trough begins to weaken and move out over the weekend. This will
bring us a warming trend, and a shallower marine layer for Sunday
into Monday. A new weak upper low from the northwest will float
across SoCal Monday and Tuesday, which should deepen the marine
layer and extend the coastal clouds. Today we`ll have max temps a
few degrees below normal except inland valleys should reach a
little above. We warm up this weekend, so that by Sunday max temps
should be 0-8 degrees above normal. The 0-degree difference
representing the coast and the 8-degree difference in the low
desert, probably hitting 100 degrees. For the second half of next
week, there is unsurprisingly a large spread in ensemble
guidance. An amplified high-pressure ridge develops over the
West, but with weak low pressure directly south of it, what we
call a Rex Block. SoCal lies within the lower pressure embedded
under the strong high pressure, so the forecast picture gets
wishy-washy. A minority of members indicate some low pressure and
moisture leading to showers, but a majority of members keep our
weather dry. For now our forecast is dry with a warming trend,
with uncertainty mainly concerned with how deep and dominant the
marine layer will be.
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&&

.AVIATION...
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101615Z...Coast/Valleys...Areas of low clouds with bases 1800-2200
ft MSL and tops to 3000 ft with local VIS 1-4 miles in BR, mainly in
the valleys through 18Z, and local terrain obscurations in clouds.
The valleys will clear through 18Z. Slower valley clearing KCRQ
southward. Some patchy coastal BKN CIG near 2000 ft MSL lasting
through this evening...then low clouds will spread farther inland
Fri evening.

Mountains/Deserts...SCT/BKN clouds will develop again Fri afternoon
over the mountains with bases around 2000 ft MSL with local TCU
possible. Otherwise, mostly clear skies will prevail through this
evening with unrestricted VIS.
-- End Changed Discussion --

&&

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

&&

.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...MM
AVIATION/MARINE...Small