251
FXUS66 KLOX 130430
AFDLOX

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

.SYNOPSIS...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.

&&

.SHORT TERM (TDY-TUE)...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 (WED-SAT)...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.

&&

.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...12/928 PM.

Moderate to high confidence in the current forecast. Higher
confidence in the forecast for seas versus winds.

For the waters southwest through northwest of the Channel Islands
and along the Central Coast, there is a 60-80 percent chance of
Small Craft Advisory (SCA) winds from Point Sal south to San
Nicolas Island, decreasing to 50-60 percent on Monday afternoon
and evening. There is a 30-40 percent chance across the waters
north of Point Sal Monday afternoon through Monday night.
Otherwise, SCA conditions are not expected through Thursday over
the Outer Waters.

Inside the southern California bight, winds and seas will remain
below SCA levels the period, except for a 30-50 percent chance of
SCA winds tonight across the western half of the Santa Barbara
Channel, decreasing to 10-30 percent chance on Monday afternoon
and evening.

&&

.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...Hall
SYNOPSIS...MW

weather.gov/losangeles

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