Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 221600
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
900 AM PDT Tue Aug 22 2017

.SYNOPSIS...
High temperatures for inland areas expected to increase to near
seasonal averages today, then slightly cooler for Wednesday and
Thursday. Areas of night and morning coastal low clouds and
patchy fog will extending locally into the western valleys with
some afternoon clouds over the mountains. A warming trend begins
on Friday, with temperatures returning to seasonal averages.
Temperatures increase to 5 to locally 10 degrees above average
for Saturday through Monday.

&&

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

Marine layer low clouds cover most of the coastal areas and
portions of the inland valleys this morning. The morning sounding
and various webcams indicate the marine layer about 1800-2000 ft
deep this morning, with southwest flow aloft. Farther to the east,
the flow aloft is more southerly and some mid and high-level
clouds can be seen moving northward across Imperial County.

The weak upper level low pressure system off the central
California coast will remain nearly stationary today, with high
temperatures inland from the coast warming to near seasonal
averages. The marine layer clouds are likely to burn off in a
similar manner to yesterday.

For Wednesday and Thursday...the weak low pressure system off the
central California coast will weaken as it moves inland through
Southern California. This will bring slight cooling with high
temperatures for inland areas a few degrees below average. Areas
of night and morning coastal low clouds and fog will extend into
the western valleys. Some of the higher resolution models show an
area of elevated instability moving across portions of
southwestern California from the south late tonight and early
Wednesday...however moisture aloft remains quite limited. This may
bring some mid level clouds into our area...but any chances for
precipitation are quite limited. Otherwise...there may continue to
be some afternoon clouds near the mountains into the upper
deserts the next few days.

Friday through Monday... High pressure aloft over northwest
Mexico on Friday...will expand into the southwest states and Great
Basin for Sunday and Monday. High temperatures for inland areas
will warm to near average on Friday...then warm to 5 to locally 10
degrees above average. The marine layer will become shallower
with areas of night and morning coastal low clouds and patchy fog
not extending inland much past the coastal areas. Mid level
moisture may increase somewhat during the weekend into early next
week with more afternoon clouds for the mountains, however the
global models are keeping precipitation mostly to the east.

&&

.AVIATION...
221530Z...Coast/Valleys...Low clouds, with bases 1300-1500 ft MSL
and tops near 1800 ft MSL, will continue to clear towards the coast
by late morning. Inland areas with VIS of 2-4 SM BR/HZ will improve
to P6SM by early afternoon. Stratus will redevelop along the coast
tonight, and push around 20 SM inland by early Wednesday morning
with slightly higher tops and bases.

Mountains/Deserts...Mostly clear skies and unrestricted visibility
through Wednesday morning.

&&

.MARINE...
No hazardous marine weather is expected through Saturday.

&&

.SKYWARN...
Skywarn activation will not be needed today.

&&

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

&&

$$

PUBLIC...PG
AVIATION/MARINE...JJT



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