Area Forecast Discussion
Issued by NWS Los Angeles, CA

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000
FXUS66 KLOX 151236
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
536 AM PDT Wed Aug 15 2018

...Aviation and marine discussions updated...

.SYNOPSIS...15/401 AM.

A warming trend is expected through Friday. Above normal temperatures
will persist into next week. There will be decreasing night through
morning low clouds and fog, becoming confined to the immediate coast
by Friday. There is a slight chance of afternoon and evening
thunderstorms across the Antelope Valley and eastern mountains of
Los Angeles County Thursday.

&&

.SHORT TERM (TDY-FRI)...15/402 AM.

Low clouds were widespread on the Central Coast and in the Santa
Ynez Valley early this morning. A weak eddy circulation has
developed across the inner waters, and clouds have finally begun
to push into coastal sections of L.A. County from the south. With
a 1400 foot deep marine layer, clouds should have no problem
spreading into the San Gabriel Valley and at least portions of
the San Fernando Valley by daybreak. Expect some clouds to push
northward into coastal sections of VTU County and possibly the
south coast of SBA County, but confidence on that is a bit lower.
Skies should clear by mid morning in the valleys and late morning
across most of the coastal plain. However, clouds could linger
into the afternoon at some beach locations. There will be little
change in heights/thicknesses and temps at 950 mb today. Onshore
flow will be slightly weaker, but that should be offset by more in
the way of low clouds this morning, especially across L.A. County.
Therefore, expect max temps today to be very similar to those
observed yesterday in most areas. There will be some monsoonal
moisture approaching eastern L.A. County today, along with
marginal instability, but it still looks as though there will just
be some buildups in the mtns this afternoon and evening.

Very little change in the pattern through Friday. A very weak
upper low will drift eastward into Baja CA today, then an upper
high in Texas will expand westward into the region. Heights and
thicknesses will rise some, bringing some warming each day to
interior sections. The marine layer is expected to become more
shallow through Fri as heights rise, with minimal low clouds/fog
in the valleys tonight/Thu morning, then clouds should be
confined to the coastal plain Thu night/Fri morning. This should
allow some warming west of the mtns, especially in the valleys,
where highs should reach 100 degrees in the warmest locations
Fri. There is a better surge of mid level moisture into eastern
sections of the region on Thu, with a slight chance of afternoon
and evening thunderstorms across the Antelope Valley and the eastern
San Gabriel Mountains. On Fri, it appears that any tstorm activity
will remain south and east of the region.

.LONG TERM (SAT-TUE)...15/432 AM.

Models show the upper high lingering over the region thru at least
Mon, with little day to day change in weather conditions. There will
be minimal night/morning low clouds and fog, mainly in areas within
a few miles of the coast, and temps should be a few degrees above
normal. Monsoonal moisture should remain south and east of the
region. The 06Z GFS shows an upper low pushing into northern CA
Tue and the upper high weakening and moving eastward. The EC shows
the upper high lingering over the region. See no reason to make any
changes to a day 7 forecast based on one run of one model, so will
keep the forecast as is for Tue. As mentioned, temps will likely
above normal for several days, but probably not to the point where
excessive heat watches/warnings or advisories will be required.

&&

.AVIATION...15/1212Z.

At 0815z at KLAX... the inversion was around 800 feet. The top of
the inversion was around 3700 feet with a temperature of about 25
degrees Celsius.

Overall... Low to moderate confidence in coastal/KPRB TAFs and
moderate to high confidence in the inland TAFs. IFR/MVFR
conditions will affect much of the coastal area through 17z and
then return after 07z. There is an eighty percent chance of
LIFR/IFR conditions at KPRB 1330z-15z. There is a twenty percent
chance of IFR/MVFR conditions at KVNY and KBUR during the 13z-16z
period. Otherwise and elsewhere VFR conditions will prevail.

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
twenty percent chance of IFR/MVFR conditions 13z-16z. Otherwise
VFR conditions will prevail.

&&

.MARINE...15/535 AM.

For the Outer Waters... Small Craft Conditions (SCA) will
continue across the central and southern outer waters through mid
morning then will diminish to below advisory criteria through
early afternoon. Conditions will again strengthen to SCA levels
by late afternoon across all of the outer waters and will continue
through early Thursday morning. There is a forty percent chance
that SCA conditions will prevail across the outer waters during
the same afternoon through early morning period Thursday through
Saturday.

For the Inner Waters north of Point Conception... Conditions will
remain below SCA levels through at least Thursday. There is a
forty percent chance that conditions will reach SCA levels in the
late afternoon and evening hours Friday and Saturday.

For the Inner Waters south of Point Conception... Conditions are
expected to remain below SCA levels through Saturday.

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

Increased south swell will arrive by this evening which may result
in hazards for mariners through the end of the week, especially
near the surf zone.

&&

.BEACHES...15/205 AM.

A south swell will increase by this evening and remain elevated
through Friday evening. This will bring surf of three to six feet
on south facing beaches as well as strong rip currents and sneaker
waves.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement in effect from this evening through
      Friday evening for zones 40-41-87. (See LAXCFWLOX).
PZ...Small Craft Advisory in effect from 3 PM this afternoon to 3
      AM PDT Thursday for zones 670-673-676. (See LAXMWWLOX).
     Small Craft Advisory in effect until 9 AM PDT this morning
      for zones 673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK (FRI-TUE).

No significant hazards expected.

&&
$$

PUBLIC...DB
AVIATION...Kj
MARINE...Kj
BEACHES...Kj
SYNOPSIS...DB

weather.gov/losangeles



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