Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 250023 AAA
AFDLOX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
523 PM PDT TUE MAY 24 2016

...UPDATE FOR NEW AVIATION DISCUSSION...

.SYNOPSIS...

Low pressure will move across the area today and tomorrow,
resulting in cool weather and a slight chance of showers and
thunderstorms, mainly for the mountains and some interior areas.
Warming is expected late this week as the main upper low moves
east, but temperatures will remain near or slightly below normal
through early next week as a weak trough lingers over the area.

&&

.SHORT TERM...(TDY-FRI)

Satellite imagery showing considerable stratocumulus clouds
across interior sections of forecast area this afternoon. With
moist layer between 5000 and 7000 feet deep and strong onshore
flow in place, a "reverse clearing day" underway, with better
clearing along coastal areas compared to inland areas. Another
fairly cool day with temperatures remaining in the 60s across much
of the area. The strong onshore flow also resulting in wind gusts
of 30 to 40 mph across the mountains and Antelope Valley this
afternoon and evening, with isolated gusts as high as 50 mph in
the foothills near Lake Palmdale.

Weak upper level pressure system approaching the Central Coast
this afternoon. The proximity of this upper low will continue to
bring some cooler air aloft, with 500 mb temperatures of -18 to
-19 degrees Celsius across interior sections from Ventura county
westward. 12Z NAM model cross sections showing ample low level
moisture this afternoon/evening across interior sections of
SLO/SBA/Ventura counties this afternoon and evening, with slight
chance to chance pops highlighted for these areas. From noon to
2 pm, an area of showers has developed along Highway 58 across
interior SLO County. Otherwise, just some scattered showers
observed across adjacent zones in Monterey`s and Hanford`s
forecast areas.

As the upper level low pressure system moves into forecast area
later tonight into Wednesday morning, the colder air aloft (-20
degrees Celsius at 500 mb) will provide sufficient instability to
maintain a slight chance of showers across interior sections of
the forecast area. With afternoon forecast, have expanded 20
percent chance of showers to include all areas south of Point
Conception on Wednesday morning as weak closed low moves overhead.
By Wednesday afternoon, the upper low is forecasted to be just to
our east of the forecast area. However some wrap around moisture
and slightly better instability will keep a slight chance of
showers/tstms for much of the interior sections on Wednesday
afternoon. On Wednesday afternoon/evening, gusty west to
northwest winds will impact the mountains, Antelope Valley, and
SBA South coast, with wind gusts approaching advisory levels.

Dry slightly cyclonic flow aloft sets up Thursday into Friday as
the upper low exits the state. There should be enough of a marine
inversion across the central coast to allow for stratus
development...but south of point conception it will just be
another partly cloudy night as a deep moist layer with no
inversion creates some partly cloudy skies. Max temps will warm a
few degrees but will still be below normal.

.LONG TERM...(SAT-TUE)

Extended models showing weak upper level trough across California
over the weekend, with continued strong onshore flow near the
surface. This will maintain mild temperatures, along with night
and morning marine layer clouds, and gusty onshore winds in the
mountains and deserts. Some weak upper level ridging expected to
follow Monday into Tuesday, leading to a few degrees of warming
across interior areas.

&&

.AVIATION...

25/0010Z...

At 2329Z...a weak marine inversion was present at KLAX at around
1700 ft deep. The top of the inversion was around 2400 ft with a
temperature of 13 deg C.

Moderate confidence overall in the 00z TAFs. Periods of low clouds
with MVFR cigs are expected at the coastal and vly airfields tonight
and Wed morning, but the timing of the clouds could be off +/- an
hour or two, be intermittent at times, and may not fall to MVFR
flight cats at some of the airfields. Otherwise, VFR conditions will
prevail thru Wed. For KWJF and KPMD, VFR conditions will continue
thru Wed along with gusty afternoon and evening winds, altho the
winds should be a bit stronger on Wed.

KLAX...Moderate confidence overall in the 00z TAF. Low clouds with
MVFR cigs are expected from about 03z to 20z. However, the timing of
the clouds could be off +/- an hour or two, be intermittent at
times, and may not even fall to MVFR at times. Otherwise, VFR
conditions will prevail at the airfield thru Wed evening.

KBUR...Moderate confidence overall in the 00z TAF. Low clouds with
MVFR cigs are expected from about 08z to 18z. However, the timing of
the clouds could be off +/- an hour or two, be intermittent at
times, and may not even fall to MVFR at times. Otherwise, VFR
conditions will prevail at the airfield thru Wed afternoon.

&&

.MARINE...24/200 pM.

There is a 20 percent chance that Small Craft Advisory level wind
gusts will develop across the outer waters from Point Sal to San
Nicolas Island to the west out 60 NM this afternoon through this
evening. Otherwise not expecting SCA wind gusts elsewhere through
Wednesday morning. However, there is a high probability that Small
Craft winds will develop across the outer waters Wednesday
afternoon through at least Friday morning. There is also a good
chance that SCA level wind gusts will affect the western portion
of the Santa Barbara County Channel Wednesday afternoon through
early Thursday morning. 40 percent chance that the NW portion of
PZZ 655 near Anacapa Island will meet SCA criteria as well
Wednesday evening into early Thursday morning.

At this time it looks like SCA wind gusts will occur across the
western portion of the outer waters from Friday through the
weekend...and into early next week. A Catalina Eddy will likely
spin up most night through mornings across the inner waters within
the SoCal Bight.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.

&&

$$

PUBLIC...Gomberg
AVIATION...Sirard
MARINE...Sweet
SYNOPSIS...Sukup

weather.gov/losangeles


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