000
FXUS66 KSGX 231016
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
316 AM PDT Wed May 23 2018

.SYNOPSIS...
Seasonal weather for the latter part of May will continue with
onshore flow keeping coastal and valley areas cooler with night
and morning low clouds and fog lingering near the coast some
afternoons. The marine layer will become a little shallower 
through Thursday...then deepen for Friday and Saturday...then 
become gradually shallower through early next week. There will be 
gusty southwest to west winds in the mountains and deserts each 
late afternoon through late evening...strongest on Friday and 
Saturday. Inland high temperatures will cool through Saturday to 
10 to 15 degrees below average...then warm early next week 
returning to around average on Tuesday.

&&

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

Seasonal weather for the latter part of May in Southern California
will continue into next week. Upper level low pressure centered 
over the Great Basin will weaken and move northeastward with weak 
high pressure across Southern California through Thursday. The 
marine layer was near 4000 feet deep Tuesday afternoon with 
coastal low clouds extending onto the lower coastal mountain 
slopes early this morning. The marine layer will become gradually 
shallower into Thursday but remain sufficient deep for coastal low
clouds to extend into the far inland valleys for Wednesday night 
into Thursday morning. 

High temperatures won't change much through Thursday...then will 
cool for Friday into Saturday as a low pressure system off the 
California coast moves slowly inland. It will bring deepening of
the marine layer for Friday into Saturday with coastal low clouds
extending inland onto the lower coastal mountain slopes. There
could also be some patchy drizzle...especially late Friday night 
into Saturday morning. Clearing could be more limited near the 
coast. There will be stronger onshore flow for Friday into 
Saturday with periods of stronger and gusty southwest to west 
winds in the mountains and deserts.

For Sunday through early next week...that low pressure system will
continue to move slowly inland and weaken. The marine layer will 
become a little shallower for Monday and Tuesday...but still be 
sufficiently deep for coastal low clouds to extend into portions 
of the valleys. High temperatures 10 to 15 degrees below average 
on Saturday for inland areas will warm to near average on Monday 
and a little above average on Tuesday. 

&&

.AVIATION... 
230900Z...Coast/Valleys/Coastal Mountain Slopes...Low clouds filling 
the coastal basin with bases between 1500 and 2500 feet MSL and tops 
to 3700 feet. Some terrain obscuration between those elevations. 
Some scatter out forecast between 16-20Z with low confidence on 
timing or location of scatter out. Low clouds will gradually fill 
the coastal basin tonight after 03Z.

Mountain Crests/Desert Mountain Slopes/Deserts...Mostly clear skies 
and VFR conditions today and tonight. Some afternoon cumulus over 
the higher mountains. Breezy westerly winds through mountain passes 
with gusts 25-35 mph late this afternoon and evening.

&&

.MARINE...
No hazardous marine conditions are expected through Sunday. 
Occasional wind gusts over 20 knots are possible over the outer 
waters during the afternoons and evenings Friday and Saturday.

&&

.BEACHES...
A long-period southerly swell will continue to produce elevated surf 
through Thursday mainly in Orange and northern San Diego Counties, 
subsiding thereafter. Check the Surf Zone Forecast and the Beach 
Hazards Statement for details.

&&

.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 Thursday afternoon for Orange 
     County Coastal Areas-San Diego County Coastal Areas.

PZ...NONE.

&&

$$

PUBLIC...17
AVIATION/MARINE/BEACHES...MM

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  National Oceanic and Atmospheric Administration
  National Weather Service
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