Area Forecast Discussion
Issued by NWS San Diego, CA

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380
FXUS66 KSGX 201038
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
338 AM PDT Sat May 20 2017

.SYNOPSIS...
High pressure aloft off the West Coast will bring a slow warming
trend through Tuesday which will take high temperatures to around
10 degrees above average. High temperatures towards the coast will
peak today around 10 to 15 degrees above average...then slowly
cool through Tuesday as the marine layer returns and slowly
deepens. Cooling for all areas will spread inland for Wednesday
through Friday as a trough of low pressure moving inland to the
north increases onshore flow across Southern California. This
will also bring greater deepening of the marine layer with gusty
southwest to west winds in the mountains and deserts for each late
afternoon through late evening. Warming will return for next
weekend with high pressure aloft near the West Coast.

&&

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

High pressure aloft off the West Coast and weak offshore flow will
bring warmest high temperatures for coastal and western valley
areas today with high temperatures 10 to 15 degrees above average.
Weak onshore flow will return for tonight through Tuesday with
patchy stratus returning near the coast late tonight into early
Sunday morning with slowly increasing coverage and inland extent
through Tuesday as the marine layer slowly deepens. Slow cooling
will spread inland for coastal and valley areas for Sunday through
Tuesday.

Farther inland...slow warming will continue for today through
Tuesday with high temperatures in the lower deserts peaking on
Tuesday around 10 degrees above average with high temperatures
around 107.

For Wednesday through Friday...a trough of low pressure will move
inland to the north with stronger onshore flow for Southern
California. High temperatures slightly above average near the
coast on Wednesday and 4 to 8 degrees above average for inland
areas...will cool to slightly below average on Friday. The marine
layer will continue to deepen with areas of night and morning low
clouds and fog spreading farther into the valleys. The stronger
onshore flow will also bring gusty southwest to west winds to the
mountains and deserts each late afternoon through late evening.

High pressure aloft will return near the West Coast next weekend
with slow warming.

&&

.AVIATION...
200930Z...Clear with unrestricted visibility through early Sunday.
There is a small chance of developing along the coast and up to 5
miles inland after 21/12Z with CIGS below 500 ft MSL and vis 1SM or
less.

&&

.MARINE...
Patchy dense fog may develop over the coastal waters Sunday into
Sunday night. Otherwise no hazardous marine weather is expected
through Wednesday.

&&

.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...17
AVIATION/MARINE...SS



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