000
FXUS66 KLOX 161209
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
509 AM PDT Thu Aug 16 2018

...Aviation discussion updated...

.SYNOPSIS...15/925 PM.

High pressure aloft will return later this week for a warmup and
with less night through morning low clouds through next week. Any
marine layer clouds will likely remained confined to the coast.
There is a slight chance of afternoon and evening showers and
thunderstorms across the Los Angeles and Ventura County mountains
and the Antelope Valley this afternoon and evening.

&&

.SHORT TERM (TDY-SAT)...16/310 AM.

CA is between a weak upper trof to the NW and a large upper high
centered over TX. Gradients are weakly onshore and similar to last
night. The marine layer has increased to 1600 feet and a weak eddy
has brought low clouds as far north as Oxnard. The Central coast
is already enveloped by low clouds and by dawn almost all of the
coastal areas will be covered with low clouds. The depth of the
marine layer will allow it to move into the San Gabriel and San
Fernando Vlys. The gradients are weak and this will allow total
clearing by late morning. Hgts are 589 DM and max temps today will
come in within a degree or two of normal. The biggest question
today will be the afternoon convection. Right now a little outflow
is moving across the deserts towards LA county but Satellite shows
it weakening and will not much affect LA county. It looks like
there is a good chc of a tstm or two developing over the
Wrightwood area and the western portions of the Antelope Vly there
is a lesser chc of a TSTM over the rest of the LA mtns and the
higher peaks of the VTA mtns. Right now the bulk of the moisture
is forecast to remain to the east and south of the area but heavy
rains are still possible and any TSTM that forms will need close
watching.

Not much change tonight. Skies may be partly cloudy due to monsoon
debris clouds. The eddy looks weaker and it appears that the SBA
south coast will remain clear although this is not a sure thing.

The trof asserts itself over the state on Friday at least as far
as the flow pattern is concerned. The upper flow will turn more
westerly and this will eliminate the convective threat. Despite
the trof hgts actually rise a little and most areas will be a
degree or two warmer than today.

On Saturday an upper ridge bulges into the state from the SW and
by the afternoon it develops into an upper high over the state.
Hgts increase to 595 DM. The marine layer and the gradients look
similar and max temps will bump up by a degree over most area and
will be a degree or two above normal.

.LONG TERM (SUN-WED)...16/315 AM.

A pretty quiescent xtnd forecast. Both the EC and the GFS agree
that a trof will move in over the PAC NW and the upper high will
move to the east and set up over western NM. Hgts will fall to 590
DM on Sunday and then will change little through mid week.

Temps will fall to normal on Sunday and then will change little
over the next three days. The marine layer stratus will be
confined to the coast with the exception of the SBA south coast.

The convective threat looks minimal through the forecast period
but it looks like it could become more active at the end of the
week.

&&

.AVIATION...16/1203Z.

At 1100z at KLAX... the inversion was around 1300 feet. The top
of the inversion was around 3300 feet with a temperature of about
26 degrees Celsius.

Overall... Low to moderate confidence in coastal and KVNY/KBUR TAFs
and high confidence in the other TAFs. IFR/MVFR conditions will
affect much of the coastal area through 17z and then return after
07z. There is a fifty five percent chance of IFR/MVFR conditions
at KVNY and KBUR during the 1230z-16z period. Otherwise and
elsewhere VFR conditions will prevail. There is a slight chance of
thunderstorms in the Antelope Valley 21z-02z.

KLAX... Moderate confidence in the current TAF. IFR/MVFR conditions
will prevail through 16z then return 09z-16z. Otherwise VFR
conditions will prevail. No east winds greater than eight knots
are expected during the forecast period.

KBUR... Moderate to high confidence in the current TAF. There is a
fifty five percent chance of IFR/MVFR conditions 13z-16z. Otherwise
VFR conditions will prevail.

&&

.MARINE...16/234 AM.

For the Outer Waters... There is a thirty five percent chance of
Small Craft Advisory (SCA) conditions across the northern outer
waters late this afternoon through late evening. There is also a
forty percent chance of SCA conditions across the entire outer
waters late afternoon through late evening on Saturday. Otherwise
and elsewhere conditions across the outer waters will remain
below SCA level through Monday.

For the Inner Waters... There is a twenty percent chance of SCA
conditions north of Point Conception in the late afternoon and
evening hours today and Saturday. Otherwise and elsewhere
conditions across the inner waters will remain below SCA level
through Monday.

Patchy dense fog will form in the overnight and morning hours in
portions of the coastal waters through the rest of the week.

Increased south swell will result in hazardous conditions for
mariners through the end of the week, particularly near the surf
zone.

&&

.BEACHES...16/211 AM.

A southerly swell will keep surf heights elevated across the region
through at least Friday evening which will also bring strong rip
currents and sneaker waves. Surf will be three to six feet on the
south facing beaches of Ventura and Los Angeles Counties and four
to seven feet along the Central Coast.

This swell will slowly diminish through Sunday so the risk of
moderate to strong rip currents and sneaker waves will also
diminish but remain a hazard through the weekend.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement in effect through Friday evening for
      zones 40-41-87. (See LAXCFWLOX).
PZ...NONE.

&&

.HAZARD POTENTIAL OUTLOOK (SAT-WED).

No significant hazards expected.

&&
$$

PUBLIC...Rorke
AVIATION...Kj
MARINE...Kj
BEACHES...Kj
SYNOPSIS...Hall

weather.gov/losangeles




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