Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 200957
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
257 AM PDT Sun Aug 20 2017

.SYNOPSIS...
A weak low pressure system off the Southern California coast will
keep high temperatures a few degrees below average through Monday
with areas of night and morning coastal low clouds and patchy fog
extending into portions of the inland valleys. Mid level monsoonal
moisture to the east and north will bring some afternoon clouds
to the mountains with a slight chance for thunderstorms for the
San Bernardino County mountains and adjacent deserts for Monday
afternoon. There will be warming to near average high temperatures
for Tuesday through Thursday...then a few degrees above average
for next weekend.

&&

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

A weak low pressure system will remain off the Southern California
coast through Tuesday...then weaken and move inland on Wednesday
and Thursday with a trough of low pressure moving inland through
the Pacific Northwest and northern Rockies for Thursday into
Friday.

While the atmosphere aloft over the Southern California coastal
waters into adjacent coastal areas will remain quite dry...the
cyclonic circulation around the low pressure system will draw
some mid level moisture northward and northwestward across the
eastern deserts of Southern California. The models have trended
slightly farther to the north and east with more significant
moisture that will be drawn northward tonight into Monday morning.
This lessens the chances for any nocturnal convection tonight to
extend into southwestern California. Some clouds are expected
near the mountains into the adjacent deserts of San Bernardino
County for this afternoon...with a slight chance of thunderstorms
for the San Bernardino County mountains and adjacent deserts for
Monday afternoon.

High temperatures will remain a few to around 5 degrees below
average for today and Monday. Areas of night and morning coastal
low clouds and patchy fog will extend into portions of the inland
valleys.

For Tuesday through Thursday...high temperatures will return to
near average with areas of night and morning coastal low clouds
and patchy fog extending into the western valleys.

For next weekend...high pressure will begin to develop over
Arizona. This will bring warming with high temperatures warming to
around 5 degrees above average with night and morning coastal low
clouds and patchy fog not extending much farther inland than the
far western valleys. Some mid level moisture in southeast flow
aloft may return some afternoon clouds to the mountains.

&&

.AVIATION...
200915Z...Coast/Valleys...Low clouds with bases 1500-2000 ft MSL
will continue to spread 25-30 mi inland through 14Z. Local vis 3-5
SM where stratus nears higher terrain in the valleys. Slow clearing
to the coast 17-20Z, with only partial clearing at the beaches.
Stratus returning to the coastal areas 21/00-03Z and spreading into
the western valleys overnight. Bases will remain around 1500-2000 ft
MSL.

Mountains/Deserts...Mostly Clear skies and unrestricted visibility
through Monday morning.

&&

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

&&

.BEACHES...
A 2-3 ft/14-15 sec period swell from 200 degrees will continue
today, producing surf of 3 to 5 ft north of Oceanside. Strong rip
currents will accompany the surf. High tides this evening will peak
around 6.5-6.7 feet, possibly leading to minor tidal overflow. A
Beach Hazards Statement remains in effect through early Monday
morning.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement through this evening for Orange County
     Coastal Areas-San Diego County Coastal Areas.

PZ...NONE.

&&

$$

PUBLIC...17
AVIATION/MARINE/BEACHES...SS


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