Scientific Forecaster Discussion

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Southwest California area forecast discussion 
National Weather Service Los Angeles/Oxnard California
500 am PDT sun Apr 20 2014

Aviation discussion updated...

Synopsis...
a weak ridge will continue the warming trend through Monday.
Overnight low clouds and fog are expected on parts of the coast.
Another trough will pass through Tuesday and Wednesday...with cooler
temperatures...gusty winds...and a slight chance of showers in San
Luis Obispo County. Some warming will follow with another ridge.

&&

Short term (today-tue)...
low clouds struggling to form south of Point Conception and will
likely only really affect the la coast with only patchy clouds
reaching to the vta coast. A shallower marine has brought a blanket
of low clouds to the area north of pt Conception along with dense
fog. A dense fog advisory is in effect through 900 am for the
central coast and the Santa Ynez Valley. Otherwise a sunny and warm day
in fact the warmest of the next 7 as plenty of sunshine mixes with
580 heights.

Not much change Monday with just a little more low clouds and a
little cooler temperatures as the ridge pushes off to the east.

On Tuesday a trough with a very weak front moves across the area.
Skies will be mostly cloudy during the morning and the far northwest tip of
slo County will have a slight chance of rain. Skies will clear to
partly cloudy in the afternoon as the front and trough move to the
east. The big deal with this system will be the winds. Strong northwest to
north winds will work into the area behind the front and wind advisories
may well be needed across the Antelope Valley...the mountains and the sba
South Coast. It will be breezy across the valleys as well. Maximum temperatures
will fall 4 to 8 degrees across the area.

Long term (wed-sat)...
dry west-northwest zonal flow sets up Wednesday and Thursday. It will be too cool for any
marine inversion to form Wednesday so skies will be mostly clear or
partly cloudy depending on how optimistic/pessimistic you are. The
extra sunshine will allow for a couple of degrees of warming. A
little marine layer cloud deck may form over the l.A. Coast Thursday
morning but otherwise it will be sunny day and maximum temperatures will warm a
few more degrees.

A trough will approach the area Friday. The marine layer will grow and
will extend locally into the valleys. After the morning low clouds
clear skies will turn partly cloudy as middle and high level clouds
arrive ahead of the trough. Maximum temperatures will cool 2 to 4 degrees.

The trough will move over the area Saturday. For now just put a mostly
cloudy and cooler wording into the forecast. The GFS and the Canadian
bring rain to the area but the ec is dry. Perhaps ec and GFS will
come into agreement today and we can get a better handle on the wet
vs dry forecast.

&&

Aviation...20/12z
moderate to high confidence in the 12z tafs with the reduced
confidence due to the timing... intensity... and location of patchy
coastal low clouds and fog. North of Point Conception through 18z
there is a 60 percent chance of vlifr-LIFR conditions. South of
Point Conception through 18z there is a 60 percent chance of MVFR
conditions and a 20 percent chance of IFR conditions. Klax after
11z tomorrow morning again has a 60 percent chance of MVFR
conditions otherwise and elsewhere... VFR conditions are expected.

Klax...moderate to high confidence in the 12z taf with the reduced
confidence due to the timing... intensity... and location of patchy
coastal low clouds and fog. Through 18z there is a 60 percent
chance of MVFR conditions and a 20 percent chance of IFR conditions.
After 11z tomorrow morning again there is a 60 percent chance of
MVFR conditions otherwise VFR conditions are expected.

Kbur...high confidence in the 12z taf. VFR conditions are expected
throughout the forecast period.

&&

Lox watches/warnings/advisories...
dense fog advisory (see laxnpwlox).
Small Craft Advisory (see laxmwwlox).
High surf advisory (see laxcfwlox).
Marine weather statement (see laxmwslox).

&&

$$

Public...rorke
aviation...kj
synopsis...b

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