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270
FXUS66 KLOX 130338
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
838 PM PDT Sun May 12 2024

.SYNOPSIS...
-- Changed Discussion --
12/837 PM.

Quiet weather will continue the next several days with near
to slightly below normal temperatures. Widespread night and
morning low clouds are expected across coast and valleys as
onshore flow increases. Temperatures will cool slightly through
Wednesday, then warm slightly the end of the week. Gusty winds are
likely across the mountains and Antelope Valley each afternoon.
-- End Changed Discussion --

&&

.SHORT TERM (SUN-WED)...
-- Changed Discussion --
12/836 PM.

A weak upper level ridge of high pressure over the region today
brought some warming to the interior, with portions of the
Antelope Valley reaching 90 degrees, including Palmdale and
Lancaster. Closer to the coast, strengthening onshore flow kept
things cool and moist, with persistent low clouds that did not
clear in some immediate coastal areas. The LAX-Daggett pressure
gradient peaked at +6.1 mb this afternoon, and is expected to
increase slightly on Monday and Tuesday as a weak low pressure
system approaches the coast.

Earlier this afternoon, there were some cloud buildups across
our mountains, but no showers or thunderstorms were observed.
While there is increasing instability across the mountains on
Monday afternoon, the moisture content is still minimal. At this
time, there is a 5-10 percent chance of thunderstorms on
Monday afternoon across the mountains of Ventura and Santa
Barbara counties where model soundings do show a slight influx
of mid level moisture, mainly above 10,000 feet. If any convection
were to develop, there would likely be minimal rainfall, with
gusty downdraft winds the main threat.

With Acars sounding showing the marine layer depth around 2000
feet this evening over the LA Basin, looking for low clouds
to fill in across most valley areas tonight, including the Santa
Clarita Valley. Another slow clearing day is expected on Monday
near many coastal areas, but the interior will have another
warm day, with Antelope Valley likely approaching 90 degrees
once again. There will also be increased onshore winds on
Monday afternoon/evening across the interior, especially
the Antelope Valley and adjacent foothills which could
see wind gusts of 30 to 40 mph.

*** From previous discussion ***

Temperatures will begin a slow decline, especially inland, with
most areas either at or slightly below normal. Main exception will
be the Antelope Valley and mountains which will be 3-6 degrees
above normal through the period. Onshore afternoon breezes will
be increasing, possibly to near advisory levels by Tue/Wed in the
AV. There`s a very small chance (10% or less) for showers and
thunderstorms over the mountains each afternoon. Possibly slightly
higher chances Tue as the upper low is closest in proximity
before it moves southeast Wed.

.LONG TERM (THU-SUN)...12/201 PM.

Deterministic models are closely following the ensembles mean
solution for the end of the week and into next weekend, which is
high pressure pushing closer to the West Coast Thu and Fri, then
retreating to 140w next weekend as another trough falls out of
the Gulf of Alaska and into the Pac NW. For coast and valleys
probably not much change in the drab night and morning low clouds
and fog pattern and minimal variations in daytime temps.
Mountains and interior areas will see some warming later in the
week as the high gets closer and onshore flow weakens. But then
turning slightly cooler again next weekend.
-- End Changed Discussion --

&&

.AVIATION...12/2348Z.

At 2345Z at KLAX, the marine layer was 2200 feet deep. The top of
the inversion was around 3200 feet with a max temp of 21 C.

Low to moderate confidence in coastal/valley TAFs, high confidence
in desert TAFs. Low clouds failed to clear today at KSBA, KOXR,
and KCMA and is expected to make a quick surge into remaining
coastal TAF sites and KBUR/KVNY through the evening hours.
Timing of flight cat changes may be off by +/- 2 hours. There is
a 30 percent chc of flight cats being 1 category lower than fcst
after 03Z. LIFR conditions becoming likely later tonight for
KSMX/KSBP, with a 20% chance of VLIFR conditions between 06z-14z.

KLAX...Moderate confidence in TAF. Timing of flight cat changes
could be off by +/- 2 hours, and 1 cat lower than fcst. MVFR cigs
likely to linger into Monday afternoon at KLAX. There is a 30
percent chc of a 6 kt east wind component 09-17Z Monday.

KBUR...Moderate confidence in TAF. Timing of flight cat changes
could be off by +/- 2 hours.

&&

.MARINE...12/210 PM.

For the Outer Waters, moderate confidence in forecast. There is a
60-80 percent chance of Small Craft Advisory (SCA) winds south of
Point Sal and a 30-40 percent chance across the waters north of
Point Sal this evening into tonight and Monday afternoon through
Monday night. Otherwise, SCA conditions are not expected through
Thursday over the Outer Waters.

For the Inner Waters north of Point Sal, high confidence in
forecast as winds and seas are expected to remain below SCA
levels through Thursday.

For the Inner Waters south of Point Conception, moderate
confidence in forecast for today, then high confidence. Through
Thursday, winds and seas will remain below SCA levels for most
areas. The only exception will be the western third of the Santa
Barbara Channel, where there is a 30-50 percent chance of SCA
winds at this evening through tonight.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect until 5 AM PDT Monday for
      zones 673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Gomberg/MW
AVIATION...Gomberg
MARINE...Munroe/Lund
SYNOPSIS...MW

weather.gov/losangeles

Experimental Graphical Hazardous Weather Outlook at:
https://www.weather.gov/erh/ghwo?wfo=lox