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341
FXUS66 KSGX 212147
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
247 PM PDT Mon Aug 21 2017

.SYNOPSIS...
A weak low pressure system off the Southern California coast will
keep high temperatures a few degrees below normal through
Wednesday...with areas of low clouds with patchy fog late tonight
and Tuesday morning and again Tuesday night and Wednesday morning.
There will be gradual warming to near normal high temperatures
for Wednesday through Friday...with high pressure over the Great
Basin bringing additional warming with 5 to 10 degrees above
normal for next weekend into the following early week.

&&

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

For the remainder of the afternoon and early evening, there
remains a slight chance of showers and thunderstorms over the
higher mountain peaks of Riverside and San Bernardino Counties
and the high desert of San Bernardino County...due to the western
extent of a modest monsoonal moisture plume. A decent cumulus
field has developed this afternoon in those areas. Chances for
convection will quickly end after dark this evening.

The troughy pattern along the coast will continue through Tuesday
with continued unseasonably deep marine layer influence. Low
pressure will weaken Wednesday through Friday, bringing a weaker
marine layer, and gradual warming trend to near-normal.

High pressure ridging will develop late in the weekend and into
early the following week, bringing some additional warming to a
bit above normal conditions, especially for inland locations. In
addition, some return mid level monsoonal flow will develop and
may eventually bring another chance of convection to the
mountains and deserts, although not enough confidence yet to add
to the extended forecast.

&&

.AVIATION...
211954Z...Coast/Valleys...Through 22/0000 UTC, P6SM vis and FEW
clouds AOA 10000 ft msl. 22/0000-1500 UTC, stratus will re-develop
and move inland 15-20 sm, with bases around 1200-1700 ft msl, tops
around 1800-2200 ft msl, and areas of vis 3-5 sm along higher
coastal terrain/mesas. Stratus may move in slower than the previous
night. Forecast marine layer inversion strength of around 7 deg C at
22/1200 UTC. Elsewhere, P6SM vis and FEW clouds AOA 10000 ft msl.

Mountains/Deserts...FEW-SCT clouds AOA 10000 ft msl and P6SM vis
through Tuesday morning.

&&

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


&&

.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...Brotherton
AVIATION/MARINE...Harrison