Area Forecast Discussion
Issued by NWS Los Angeles, CA

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000
FXUS66 KLOX 070352
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
852 PM PDT Thu May 6 2021

.SYNOPSIS...06/753 PM.

Low pressure along the West Coast will maintain moderate to
strong onshore flow and near-normal temperatures through the
weekend. Areas of low clouds and fog will continue, especially
for Ventura and Los Angeles Counties. A warming trend is expected
next week as high pressure returns and onshore flow weakens.

&&

.SHORT TERM (THU-SUN)...06/752 PM.

***UPDATE***

An elongated and strong upper trough centered along the west coast
of Canada, extends as far south as Central California, with a cold
front moving down the coast from the Bay Area toward coastal San
Luis County. The approaching low has already brought cooler
temperatures to Southwest California, along with increasing
onshore pressure gradients. This is bringing the usual gusty
southwest to west winds through the interior passes and canyons
into the Antelope Valley, with gusts 30 to 40 mph. In addition, a
deepening marine layer is already covering most coastal areas this
evening. As the night progresses, low clouds are expected to push
inland across all of the valleys to the lower coastal slopes. Some
drizzle may affect foothill areas overnight, and slow clearing is
expected south of Point Conception on Friday. Better and earlier
clearing is expected further north as northwest winds increase
across the area. By Friday late afternoon and evening, northerly
winds are likely to affect the Santa Barbara South Coast, with
gusts increasing to 35 mph.

***From Previous Discussion***

Saturday and Sunday fairly similar. Central Coast will likely be
mostly free of marine layer clouds but with typical breezy
northwest winds in the afternoon. Southern areas still fairly
socked in during the night and morning hours but with better
clearing during the afternoon. Temperatures within a couple
degrees of normal for coast/valleys, but a few degrees above
normal for mountains and far interior areas. Possibly near
advisory level winds in the Antelope Valley each afternoon as
onshore gradients (LAX- DAG) get close to 9mb.

.LONG TERM (MON-THU)...06/121 PM.

A second trough dropping out of Canada later Sunday will likely
help the marine layer push north to the Central Coast Monday while
maintaining a fairly deep inversion in the south. Onshore flow
will start weakening Monday afternoon as the trough passes to the
east and those trends will continue through mid week. Thus,
Tuesday should be warmer in most areas, though especially inland
and slightly warmer again Wednesday with ridging aloft. Marine
layer expected to decrease in depth and may scour out completely
up north but should stay in tact in the south, just not pushing as
far inland.

Gradients trend onshore again late Wednesday into Thursday as the
ridge weakens and a very weak trough approaches. Temps may trend a
little cooler but likely overall very little change.

&&

.AVIATION...07/0018Z.

At 1730Z, the marine layer depth was around 1400 feet deep at
KLAX. The top of the inversion was near 2800 feet with a
temperature around 20 degrees Celsius.
For KPMD and KWJF, there is high confidence in VFR conditions
thru Fri and moderate confidence in timing and peak strength of
gusty SW-W winds.

Moderate to low confidence in remaining TAFs. MVFR to IFR
conditions are generally expected with a deeper marine layer, but
LIFR conditions are still possible for SBP, SMX, and SBA.

KLAX...Moderate confidence in the 00Z TAF. The timing of the
dissipation of the low clouds may be off +/- an hour or two.

KBUR...Moderate confidence in the 00Z TAF. The timing of the
onset of the low clouds may be off +/- an hour or two.

&&

.MARINE...06/848 PM.

Outer Waters... Good confidence in GALE FORCE winds for the
waters north of the Channel Islands developing Friday, becoming
widespread by Friday night. Local gusts to 35 kts are possible
Friday morning. Lower confidence in the start time of the GALE
WATCH but it may be moved up if needed. Winds will weaken below
gale force Saturday, but ramp up again for Sunday with a 40%
chance of GALE FORCE winds. Good confidence that winds will
remain below gale force south of the Channel Islands on Friday. By
Friday night local gusts to 35 kt are possible, but currently
there is a lack of upper level support so a Gale Watch is not
expected.

Inner Waters N of Pt. Sal... Moderate to high confidence in
forecast. Winds and seas are expected to be at SCA levels for much
of the time tonight through at least Sat night, with a 50% chance
of these conditions persisting Sun and Sun night. Winds and seas
should then subside to below SCA levels for Mon and Tue.

Inner Waters S Pt. Conception... Moderate to high confidence in
forecast. Expect winds and seas to remain below SCA levels tonight
through Tue, except there is a 30% of SCA level winds across the
western SBA Channel late Sun afternoon into Sun evening.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect until 3 AM PDT Saturday for
      zone 645. (See LAXMWWLOX).
     Small Craft Advisory in effect until 5 PM PDT Friday for zone
      670. (See LAXMWWLOX).
     Gale Watch in effect from Friday afternoon through late
      Friday night for zone 670. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Friday for zone
      673. (See LAXMWWLOX).
     Gale Warning in effect from 3 AM Friday to 3 AM PDT Saturday
      for zone 673. (See LAXMWWLOX).
     Small Craft Advisory in effect from 2 AM Friday to 9 AM PDT
      Saturday for zone 676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK (SUN-THU).

No significant hazards expected.

&&

$$

PUBLIC...MW/Smith
AVIATION...Phillips/Sirard
MARINE...Phillips/Sirard
SYNOPSIS...MW/Smith

weather.gov/losangeles


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