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fxus66 klox 230016 aaa 

Area forecast discussion...updated
National Weather Service Los Angeles/Oxnard California
516 PM PDT Mon may 22 2017

..update for new aviation discussion...

very warm conditions are expected to continue through Tuesday.
A weak low pressure center will approach the southwest California
coast on Wednesday...dramatically cooling temperatures through
Friday. Overnight to morning low clouds and fog will extend
further inland each day through late in the week. A ridge of high
pressure will bring a warming trend to the area Saturday through
early next week.


Short term...(tdy-thu)

Strong inversion in place with still very warm temps inland. On
Tuesday the models actually show a Little Ridge popping up ahead
of the upper low to our southwest. This combined with a very
slight offshore trend could lead to perhaps one or two degrees of
warming inland, however along the coast likely little change as
the marine lyr will remain similar in depth and coverage with
a similar clearing (or in some cases near the coast non-clearing)

We'll start noticing the impacts of the upper low on Wednesday as
strong onshore trends and lowering heights push the marine lyr and
its cooling influence farther inland. Temps will drop 5-10 degrees
inland, still above normal but not as much so and a couple degrees
at the coast. Also of note is the models (mainly the nam) showing
impressive instability over the mtns (cape in excess of 1000 j/kg
and Li's around -5), especially Ventura and sb counties. However,
it's still very much lacking in moisture below 600 mb. The NAM
does show a very narrow tongue of moisture just below 700 mb but
otherwise very dry below that and above to around 500mb. The other
models are even drier and not nearly as impressive with the
instability. So for now will leave thunderstorms out of the
forecast Wed. Strong onshore flow expected by afternoon (lax-dag
gradient 9-10 mb) so we could see some advisory level winds out in
the Antelope Valley.

Cooling aloft will continue Thursday as the low slowly drifts
towards the coast. Significant marine lyr deepening is expected by
Thursday morning and some drizzle is possible up against the
coastal mountain slopes. A very slow clearing day, possibly
reverse clearing if anything, and high temps dropping to below
normal levels. Another windy day expected for the Antelope Valley.

Long term...(fri-mon)

One more cool, slow clearing, strong onshore flow day Friday
before the low and long wave trough shift east Saturday and a
ridge develops through early next week. High temps still likely
a few degrees below normal Saturday but warming to normal or
slightly above Sunday and then warmer still Monday. Current
forecast for Monday if anything, is a tad on the cool side if
current model projections hold.



At 2337z, the marine inversion at klax was 800 ft deep. The top of
the inversion was at 2500 ft with a temperature of 26 deg c.

Moderate confidence overall in the 00z tafs at coastal airfields.
Low clouds and IFR/LIFR cigs/vsbys will affect the coastal airfields
with the development of low clouds ranging from taf issuance time at
koxr to 09z at ksba. However, the timing of the low clouds moving
in, except for koxr, could be off +/- an hour or two. Also, the
transition between flight cats may be off +/- an hour or more. Even
so, there is hi confidence the low clouds and fog will affect these
airfields. The low clouds and fog are expected to dissipate to VFR
conditions by late Tue morning to early Tue afternoon, except should
linger thru Tue afternoon at koxr.

For inland airfields including kprb, kbur, kvny, kpmd and kwjf,
there is hi confidence in the 00z tafs with VFR conditions expected
thru Tue afternoon. However, there is a 10-20 percent chance of IFR
cigs at kbur late tonight and early Tue.

Klax...moderate confidence overall in the 00z taf. Low clouds and
IFR/LIFR cigs/vsbys is expected to affect the airfield from about
02z-20z Tue and again after about 05z Tue evening. However, the
timing of the low clouds moving in could be an hour or two too late.
Also, the transition between flight cats may be off +/- an hour or
more. Even so, there is hi confidence the low clouds and fog will
affect the airfield tonight and Tue morning. VFR conditions are
expected Tue afternoon and early evening.

Kbur...hi confidence in the 00z taf with VFR conditions expected
thru Tue afternoon. However, there is a 10-20 percent chance of IFR
cigs late tonight and early Tue


Marine...22/200 PM

Moderate confidence in the forecast. There is a 20-30% chance that
small craft advisories may needed across portions of the outer
waters during the afternoon and evening hours today through Wed.

Areas of dense fog with visibilities 1 nm or less will affect most
all coastal waters this morning, and in northern areas late
tonight and Tue morning.


Lox watches/warnings/advisories...


Hazard potential outlook...(thu-mon)
advisory level southwest winds are possible Thursday through
Friday across the mountains and deserts.



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