Area Forecast Discussion
Issued by NWS San Diego, CA

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258
FXUS66 KSGX 221519
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
819 AM PDT Sat Jul 22 2017

.SYNOPSIS...
Dry weather will continue today with seasonal Summer temperatures.
Moisture will return Sunday and Monday ahead of an easterly wave,
bringing more clouds, higher humidity, and a chance of showers and
thunderstorms. Best chance for significant rain will be over the
mountains and deserts each afternoon and early evening, provided
daytime heating is sufficient. The wave will weaken on Tuesday, but
lingering moisture and instability will continue a threat of
thunderstorms over the mountains and deserts. Along the Coast...
onshore flow and the marine layer will continue mild conditions,
with periods of nocturnal clouds and fog. Dry and warmer for the
latter half of the next week.

&&

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

Early this morning...satellite imagery showed widespread stratus
over the CA Bight, extending inland around 20 miles. Above the
marine layer and inland, it was clear. The 12Z Miramar sounding had
a 9 degree C inversion based just below 2K FT MSL. It was 300 FT+
deeper than yesterday morning. The sounding showed little potential
instability and had a PW of 1.21 inch. Surface pressure gradients
were weak and winds mostly light.

Based on the sounding this morning, it should be slightly cooler
over the inland valleys around the 2K FT elevation. No forecast
changes this morning.

From previous discussion...

Mid level moisture in southeast to east flow aloft will begin to
arrive on Sunday with some mid clouds and some afternoon clouds
near the mountains.

A greater influx of moisture is expected for Sunday night and
Monday...decreasing Tuesday and Wednesday. This will bring more
clouds...higher humidities...some inland cooling on Monday...and
chances for showers and thunderstorms...possibly spreading west of
the mountains at times with the easterly steering level flow. A
slight chance of thunderstorms will continue into Tuesday.

Dry with near seasonal high temperatures for Wednesday through
Friday with areas of night and morning coastal low clouds and
patchy fog extending locally inland.

&&

.AVIATION...
221500Z...Coast/Valleys...Low clouds with bases between 1,200 and
1,500 ft MSL will clear the coastal TAF sites between 16Z and 18Z
today, leaving patchy low clouds over the coastal waters between 18Z
Saturday and 03Z Sunday. Winds will be light this afternoon, with
standard westerly sea breezes. Low clouds with bases near 1,200 ft
MSL will creep back into coastal areas around 03Z Sunday, and spread
20-25 miles inland over the Orange and San Diego County valleys by
14Z Sunday.

Mountains/Deserts...Mostly clear skies with unrestricted visibility
will continue through 18Z Sunday.

&&

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

&&

.BEACHES...
Evening high tides will be near 7 ft today and Sunday. This could
result in minor tidal overflow in low-lying beach areas, therefore a
Beach Hazard Statement remains in effect through Sunday to account
for this possibility. Surf heights will be limited to 2-3 ft, and
this should limit the potential for tidal overflow to some degree.

&&

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

&&

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

PZ...NONE.

&&

$$

PUBLIC...JAD/17
AVIATION/MARINE/BEACHES...Albright



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