Area Forecast Discussion
Issued by NWS San Diego, CA

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FXUS66 KSGX 241651
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
950 AM PDT Thu May 24 2018

.SYNOPSIS...
A deep trough over the West will bring cooler than average weather
and a deep marine layer through Saturday. Areas of drizzle are
possible in the coastal and valley areas Friday and Saturday
mornings with limited clearing towards the coast. Gusty west winds
are forecast in the mountains and deserts Friday afternoon through
Saturday. On Sunday the trough will weaken for warmer days Monday
and Tuesday.

&&

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

.SHORT TERM (Today through Saturday)...
Rain and drizzle were widespread in the San Diego and Orange County
coastal and valley areas this morning. The highest reported amount
through 9 AM was 0.12" at Laguna Canyon in Orange County. A rainfall
summary has been headlined on our webpage. The marine layer deepened
to around 5300 feet this morning, and clouds shrouded the west and
southwest facing mountains slopes. The cloud layer was 3000-4000
feet thick this morning (bases 1000-2000 ft tops 4500-5000 ft) which
is thicker than it was yesterday, so it`ll be another slow burn back
to the coast today. It`s likely that some coastal areas will remain
mostly cloudy all day in May Gray.

Tonight the trough off the West Coast moves inland into central CA.
The marine layer will remain very deep through Saturday and there
may be areas of light rain or drizzle again each night and morning.
Cooling aloft ahead of the trough will weaken the inversion over the
next 24 hours, with 850 mb of 14C this morning falling to 9C Friday
morning. This weaker inversion may promote better mixing and earlier
clearing Friday and Saturday. The trough and the associated strong
onshore surface gradients will bring strong and gusty west winds
Friday and Saturday afternoon and evening.

Cool today through Saturday with high temperatures near the coast a
few degrees below average, and from 10-15 degrees below average in
the valleys, mountains and deserts.

*From Previous Discussion*

.LONG TERM (Sunday through Wednesday)...
Low pressure will weaken over the western states for Sunday
through Tuesday. The marine layer will become a little less deep
each day...though low clouds will still extend into portions of
the inland valleys for Sunday night into Monday morning and Monday
night into Tuesday morning. There will be greater and faster
clearing towards the coast though afternoon clearing at the coast
could continue to be slow or limited.

There will be a warming trend for Sunday through Tuesday with high
temperatures for inland areas on Monday and Tuesday around 5
degree above average. A weaker low pressure system moving inland
along the West Coast will bring a cooling trend beginning
Wednesday.

&&

.AVIATION...
241545Z...Coast/Valleys/Coastal Mountain Slopes...Stratus deck with
bases 800 to 1500 MSL and tops to 3500 ft MSL through 18Z. Patchy
fog and drizzle will reduce visibilities to 2-5SM at times. Higher
terrain will be obscured. Expect gradual clearing inland areas 18-
20Z but coastal terminals likely to retain BKN conditions. Clouds
will quickly spread back inland 25/03-06Z. Overall the cloud deck
should be thinner tonight with slightly higher bases around 1500
feet and tops around 3500 feet. Patchy fog and drizzle expected late
tonight and early Friday (10-15Z). Models indicate faster and more
widespread clearing on Friday with terminals expected to go SCT 16-
19Z.

Mountain Crests/Desert Mountain Slopes/Deserts...Winds will be the
primary concern. Expect northwest winds 15-25 kts with a few gusts
25-35 kts possible 21Z-06Z. This may result in localized LLWS with
MOD UDDFS over the mountain crests and into the deserts. Similar
conditions are expected Friday afternoon/evening except the gusts
could be a bit stronger.

&&

.MARINE...
West northwest winds with gusts near 20 knots are possible Friday
and Saturday afternoon/evening. Winds will weaken Sunday into early
next week.

&&

.BEACHES...
A long-period south swell of 3-4 ft/15-16 sec will continue to
produce elevated surf and hazardous swimming conditions through this
afternoon mainly in Orange and northern San Diego Counties. Sets to
7 ft are possible. Surf will begin subsiding tonight.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement through 6 PM today for Orange County
     Coastal Areas-San Diego County Coastal Areas.

PZ...NONE.

&&

$$

PUBLIC...Moede/17
AVIATION/MARINE/BEACHES...Moreland



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