Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 190408
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
908 PM PDT Sat Aug 18 2018

.SYNOPSIS...18/751 PM.

Above normal temperatures inland and weak onshore flow will
continue through this weekend and into early next week, as high
pressure continues to build. Night to morning low clouds and fog
will return to some coastal areas and coastal valleys through
Sunday. Little change expected going into next week.

&&

.SHORT TERM (SAT-TUE)...18/908 PM.

The latest satellite imagery shows an upper-level ridge of high
pressure centered over Southern California. The marine layer depth
is thinner than this time last night and onshore flow should
start to weaken overnight. A warm weather pattern will continue
with temperatures warming into Sunday, then temperatures remaining
above normal for early next week. At the beaches, high pressure
clamping down on the marine layer will tighten the marine
inversion. It is looking more likely the Central Coast beaches
will remain in a mix of clouds and sun on Sunday, possibly even
affecting the Santa Barbara South Coast and Ventura County
beaches.

A few tweaks were made to the forecast to tweak temperatures
closer to persistence along the Central Coast and introduce some
patchy stratus clouds into the Santa Ynez Valley. A slight tweak
in daytime temperatures was made to the mountains for Sunday to
warm up the warmer locations such as Acton.

***From Previous Discussion***

A 595-596 dm H5 high will prevail over central and srn CA today.
The upper level high will weaken thru Sun before moving E into AZ
and NM for Mon, and further E into NM for Tue. Srn CA will be on
the far western periphery of the upper level high Mon and Tue,
with H5 heights lingering in the 590-592 dm range for the most
part.

The marine layer pattern is expected to persist thru Tue, with
varying amounts of night and morning low clouds and fog expected
mainly for the coastal areas and perhaps into some of the adjacent
vlys at times. Otherwise, mostly clear skies will continue across
the region thru the period. A typical diurnal wind pattern will
prevail as well, with weak flow during the night and morning,
followed by locally gusty onshore winds in the afternoon and early
evening.

Temps will continue to be several degrees above normal across most
of the area on Sun, then cool slightly but remain a few degrees
above normal on Mon and Tue. Highs Sun should reach the mid 80s for
the inland coastal areas, and to the upper 80s to near 102 for
the vlys to lower mtns, then fall a few degrees for most areas Mon
and Tue. In the Antelope Vly, highs will be in the 101 to 106
degree range Sun, and in the upper 90s to near 103 for Mon and
Tue. Overnight lows will also continue above normal for many
areas.

.LONG TERM (WED-SAT)...18/138 PM.

The EC and GFS are in generally good agreement in the extended
period. The upper level high over NM is forecast to linger from
NM to TX Wed thru Sat, with weaker upper ridging persisting over
srn CA.

Little change in the overall wx pattern can be expected Wed thru
Sat. The marine layer pattern will remain in place for night and
morning low clouds and fog mainly along most coastal areas.
Otherwise, mostly clear skies will continue during the period.
Temps will continue to be a few degrees above normal with highs
ranging from the upper 70s to near 90 for coastal areas, mainly in
the 90s for the vlys to lower mtns, and generally from the upper
90s to 102 in the Antelope Vly. In addition, above normal sea sfc
temps will continue to bring above normal humidities and overnight
lows.

&&

.AVIATION...19/0034Z.

At 23Z, the marine layer depth was around 1000 feet deep at KLAX.
The top of the marine inversion was near 1500 feet with a
temperature around 21 degrees Celsius. There was another inversion
up to around 4000 feet.

Low to moderate confidence in the current forecast. Higher
confidence for terminals north of KNTD, less confidence south.

North of Point Conception...LIFR to IFR conditions will likely spread
into coastal and lower valley terminals through 13Z. Timing of
arrival could be off by up to 2 hours. There is a 50 percent of
LIFR developing between 07Z and 11Z, then lingering until 14Z or
15Z. VFR conditions should develop between 16Z and 18Z.

South of Point Conception...IFR to MVFR conditions will likely
spread into coastal and valley terminals through 14Z. Timing of
arrival could be off by up to 2 hours. The best chance for IFR
conditions will be north of KSMO. VFR conditions could be a little
slower to develop on Sunday. There is a chance that KOXR could
remain in MVFR conditions throughout the day.

KLAX...MVFR conditions will spread in as soon as 04Z or as late
as 09Z. There is a 30 percent chance of IFR conditions between 04Z
and 07Z. MVFR conditions should linger until at least 17Z, or as
late as 19Z. There is a 20 percent chance of MVFR conditions
linger until 21Z.

KBUR...There is a 50 percent chance of IFR conditions between 10Z
and 16Z.

&&

.MARINE...18/806 PM.

For the Outer Waters... There is a thirty percent chance of Small
Craft Advisory (SCA) level winds tonight and tomorrow night near
Point Conception, and a thirty percent chance across all of the
outer waters on Wednesday night. Otherwise conditions will be
below SCA levels.

For the Inner Waters...conditions are expected to remain below
Small Craft Advisory level through Thursday, although winds will
increase to around 20 knots by Tuesday night.

Patchy fog will form in the overnight and morning hours in
portions of the coastal waters through Wednesday. Patchy dense fog
will be possible at times as this occurs.

&&

.BEACHES...18/829 PM.

Moderate to strong rip currents and sneaker waves could linger
into Sunday as a long-period southerly swell slowly subsides.
Swimmers and anyone in the surf zone should remain vigilant
through the weekend.

&&

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

&&

.HAZARD POTENTIAL OUTLOOK (TUE-SAT).

No significant hazards expected.

&&

$$

PUBLIC...Hall/Sirard
AVIATION...Hall
MARINE...Smith
BEACHES...Hall
SYNOPSIS...Delerme

weather.gov/losangeles


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