FXUS66 KSGX 231016
Area Forecast Discussion
National Weather Service San Diego CA
316 AM PDT Wed May 23 2018
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
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.
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.
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.
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 activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
CA...Beach Hazards Statement through Thursday afternoon for Orange
County Coastal Areas-San Diego County Coastal Areas.
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