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896
FXUS66 KSGX 051623
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
923 AM PDT Wed Jun 5 2024

.SYNOPSIS...
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High pressure aloft will continue well above average high
temperatures for inland areas with the heat peaking today or
Thursday, depending on location. Only slight cooling is expected
for the lower deserts on Friday as cooling spreads inland. Gradual
cooling will continue through Sunday, with high temperatures in
the deserts still around 5 degrees above average. Night and
morning coastal low clouds will spread a little farther into the
valleys for the weekend into early next week.
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&&

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

High pressure aloft continues the warming trend for areas west of
the mountains today, with warming continuing in the deserts
through tomorrow. A slight cooling trend then sets in west of the
mountains Thursday, with cooling beginning in the deserts Friday.
Daytime temperatures will still be rather hot for most locations,
hence the continuations of the Excessive Heat Warnings and Heat
Advisory through Friday. Highs during this time will generally be
anywhere from 8 to 15 degrees warmer than seasonal averages. In
other words, these highs are more representative of what wed
expect in late July/early August. With that in mind, most of this
heat looks to be non-record-setting in terms of daily high
temperatures. On the flip side, a few daily records for warmest
overnight low temperatures do look to be challenged, mainly in
some mountain communities. More notable cooling sets in for all
areas Saturday.

With the warming trend, the marine layer looks to be a bit more
shallow and will gradually clear out a bit earlier today,
Thursday, and Friday. The low-level inversion strength however,
which was about 13C on the12z Miramar sounding, will likely remain
strong enough to keep clouds at the immediate coast through the
afternoon hours each day. The return of troughing over the Eastern
Pacific and the subsequent cooling trend this weekend into early
next week will lead to a re-deepening of the marine layer, with
low clouds getting back into more of the inland valleys later this
weekend.

The aforementioned trough and cooling trend will knock daily highs
back down to around seasonal averages across areas west of the
mountains. The mountains and deserts, however, will still see
highs remain slightly above normal, but only on the order of about
5 degrees above averages. The pattern then becomes a bit more
murky heading into next week as a closed 500mb low looks to form
off the SoCal coast underneath a broad ridge. These two competing
features make discerning trends in temperatures/sensible weather a
bit more difficult, as temperatures may only fluctuate up or down
a degree or two each day depending on marine layer depth and
associated cloud cover. Its worth nothing that we will be
starting next week with a relatively deep marine layer, generally
on the order of 2000-2500 FT MSL deep. So if the overall upper
level pattern doesnt support a very dynamic forecast, cool and
cloudy may be the prevailing theme of next week, typical for June
Gloom.
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&&

.AVIATION...
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051620Z...Coast/Valleys...Low clouds with bases 900-1200 feet MSL
and tops to 2000 feet currently covers the coastal areas and up to
20 miles inland. Vis 1-3SM BR where clouds and terrain intersect
inland and on higher coastal terrain. Inland clearing is in progress
and will continue through 19Z. Limited clearing is expected at the
coast with BKN CIGs persisting into the afternoon. Low clouds will
push inland after 00Z Thursday and locally into inland valleys again
overnight, with very similar coverage, bases and VIS.

Otherwise...Clear with unrestricted vis today and tonight.
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&&

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

&&

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


&&

.SGX WATCHES/WARNINGS/ADVISORIES...
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CA...Heat Advisory until 9 PM PDT Friday for San Bernardino and
     Riverside County Valleys-The Inland Empire.

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

PZ...None.
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&&

$$

PUBLIC...Adams
AVIATION/MARINE...PG