Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 241647
AFDLOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
947 AM PDT TUE MAY 24 2016

.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 upper low moves east,
but temperatures will remain near or slightly below normal through
early next week.

&&

.SHORT TERM...(TDY-THU)

Satellite imagery showing low clouds pushing well into the coastal slopes
of the mountains this morning, with pilot reports and soundings
showing a deep moist layer between 5000 and 7000 feet. Pockets of
drizzle and a few areas of light measurable rainfall being
reported this morning, mainly across the Central Coast and the San
Gabriel mountains. Plenty of low level moisture through the
afternoon hours combined with strong onshore flow should result
in partly to mostly cloudy conditions across the region. In fact,
with such a deep moist layer, this will likely be a "reverse
clearing day", with valley/mountain areas likely staying more
cloudy than some of the coastal areas in the afternoon. The strong
onshore flow will also generate wind gusts of 30 to 40 mph across
the mountains and Antelope Valley this afternoon, with isolated
gusts to 50 mph in the foothills near Lake Palmdale.

Another weak upper level pressure system will approach 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  model cross sections
showing ample low level moisture this afternoon/evening across the
Ventura county mountains, so definitely a chance of showers for
this area, with slight chance of showers extending across interior
sections of SLO/SBA counties. Convective parameters are marginal
this afternoo/evening, but slight chance of tstms for above
mentioned areas seems reasonable. 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. 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 convective parameters will keep a slight chance of
showers/tsmts for much of the interior sections on Wednesday
afternoon.

*** From previous discussion ***

Dry slightly cyclonic flow aloft sets up Thursday 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
lo normal.


.LONG TERM...(FRI-MON)


Both the EC and the GFS show dry NW flow on Friday followed by
broad scale west coast troffing for the Sat-Mon period. The hgt
rises Thursday evening will better establish a marine inversion
and allow for a better stratus deck to develop both north and
south of Point conception. A little more warming will bring max
temps up to just below normals.

The broad troffing aloft and onshore flow at the sfc will make for
three consecutive days of night through morning low clouds and fog
with Max temps several degrees blo normal. So it looks like the
May Grey will deftly transition to a June gloom.

&&

.AVIATION...
24/0600Z

24/1215Z

At 12Z AT KLAX there was no inversion to go along with a deep
moist layer.

Low confidence in TAFs due to a deep moist layer and not inversion
to speak of. Clouds can develop and scour out quickly. With the
trough close by, some early morning patchy drizzle will be
possible just about anywhere west of the coastal slopes this
morning. Most taf sites N of Point Conception were in and out of
IFR category with most all taf site across the CWA in MVFR status.
Categories could jump up to VFR and MVFR much of the day. There is
a 20 percent chance that CIGS along the coast could scour out
later this afternoon although most carry cigs through most of the
day.

KLAX...Low confidence in 12z TAF. Cigs could jump between MVFR and
VFR over the next 24 hours. 10-20% chance for IFR cigs to occur
after 08z tonight. There is a 20% chance that wind direction turns
SE between 15-18z but remain under 6 kt.

KBUR...Low confidence in 12z TAF. There is a 20 percent chc that mvfr
cigs will not occur through the next 24-hour period.
&&

.MARINE...24/200 AM.

There is a 40 percent chance that Small Craft Advisory level wind
gusts will develop across the outer waters from Point Sal to San
Nicolas Island to the south and 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 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
Wednesay 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...Sweet
MARINE...Sweet
SYNOPSIS...Sukup

weather.gov/losangeles


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