Area Forecast Discussion
Issued by NWS San Diego, CA

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FXUS66 KSGX 202121

Area Forecast Discussion
National Weather Service San Diego CA
221 PM PDT Sun Aug 20 2017

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
and drizzle 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.



The weak low pres trough continues just off the coast of Southern
California with an unseasonably deep marine layer remaining in
place. Coastal low clouds will develop this evening over the
coastal waters and push inland well into the western valleys
overnight. Low clouds will linger near the coast through late
Monday morning, putting a damper on the eclipse viewing
opportunities there, but away from the coast conditions will be
mostly sunny by the time of partial eclipse in Southern

A weak shortwave will swing across SE California Monday afternoon
and could generate a few showers and thunderstorms over our
northern mountains, with marginal mid level moisture there,
mainly affecting San Bernardino and Riverside Counties. Any
convection will quickly die off after dark.

Continued cool with unseasonably troughy pattern along the coast
for much of the new week with temperatures generally settling to
around normal levels.

Some ridging may develop towards the end of the week and into next
weekend, bringing a slight warmup along with a bit of mid level
moisture on a return flow pattern from the SE. No weather was
added to the forecast however during this cycle as the chances are
too low at this time.


201927Z...Coast/Valleys...through 21/0000 UTC, mostly SKC and P6SM
vis. 21/0000-1500 UTC, stratus re-developing and gradually pushing
20-50 sm inland again, with bases around 1500-2200 ft msl, tops
around 2200-3000 ft msl, and areas of vis 3-5 sm in the inland
valleys. Forecast marine layer inversion strength of 5 deg C at
21/1200 UTC. Gradual clearing of stratus during the 21/1500-1900 UTC

Mountains/Deserts...P6SM vis and mostly SKC through Monday morning.


No hazardous marine weather is expected through Friday.


A 3 ft/14 sec period southwest swell from 200 degrees will continue
today, producing surf of 3 to 5 ft north of Oceanside. Strong rip
currents will accompany the elevated surf. High tides this evening
will peak around 6.7-6.9 feet, possibly leading to minor tidal
overflow of low-lying coastal areas. A Beach Hazards Statement
remains in effect through this evening.


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


CA...Beach Hazards Statement until midnight PDT tonight for Orange
     County Coastal Areas-San Diego County Coastal Areas.



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