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933
FXUS66 KLOX 211124
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
424 AM PDT Sat Sep 21 2024

.SYNOPSIS...
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21/417 AM.

A warmer and drier pattern will establish through Monday as high
pressure aloft will build over the region. A warmer air mass will
likely remain in place through much of next week away from the
coast with the hottest daytime temperatures forecast for Monday.
Onshore flow will remain in place through the period and keep
night through morning low clouds and fog in the forecast.
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&&

.SHORT TERM (TDY-MON)...
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21/422 AM.

The latest fog product imagery indicates the marine layer stratus
deck well-entrenched across the area. A pair of eddy circulations
can be seen on satellite imagery this morning as a northwest low-
level flow remains over the outer coastal waters in the wake of
yesterday`s trough aloft. High pressure aloft will slowly build
through Monday. A warmer and drier air mass will settle into the
region as 500 mb heights climb and 1000-500 mb thickness values
increase through Monday. More significant warming is forecast away
from the coast between Sunday and Monday, but most interior
coastal and valley locations will only warm to between 4 to 8
degrees above normal for this time of year on Monday. A few
locations across the interior portions could warm closer to 7 to
12 degrees above seasonal normals. Closer to the coast and at the
beaches, a persistent onshore flow and night through morning low
clouds and fog will keep the warming trend moderated. Most coastal
cities and locales will only warm a few degrees of normal. No
heat headlines are anticipated at this time, but there is a 10
percent chance that a short heat advisory could be issued for the
Monday time period across the interior portions of the area.

.LONG TERM (TUE-FRI)...21/423 AM.

Some cooling is expected to establish for the middle portion of
next week as an upper-level trough currently located near 42N and
138W, or about 1000 miles west-northwest of Point Conception will
dig south along the California coast through Tuesday. The latest
model solutions agree with EPS, GEFS, and CMC solutions that the
trough will pull west of the state for Monday, thereby pumping up
500 mb heights some. By Tuesday, heights fall and thickness
values decline in a majority of the solutions, but CMC and some
GEFS ensemble members hold on the warmer temperatures across the
interior for Tuesday. Onshore flow should strengthen for Tuesday
through Thursday and bring a cooler pattern for the period, but
there is still a large spread across the forecast ensembles at
this time. All of the ensemble temperature means trend cooler,
but there are still a few solutions offering up a warming trend
into Wednesday. Night through morning low clouds and fog should be
more expansive for the period, making a better push into the
valley areas for Wednesday morning, and again Wednesday night into
Thursday morning. For now, NBM temperatures remain in the
forecast Wednesday and Thursday, but much warmer temperatures were
indicated for Tuesday away from the coast than NBM values.

There is a much wider spread of values for Friday and Saturday
across the ensemble members. While ensemble temperature mean
trend warmer into next weekend, some of the deterministic
solutions indicate a hot weather pattern could be setting up. The
forecast goes with NBM values for now, which leans more into a
warming trend.
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&&

.AVIATION...21/0815Z.

At 05Z at KLAX, the marine layer was 1300 ft deep. The top of the
inversion was at 4000 feet with a temp of 18 C.

High confidence in TAFs for KPMD and KWJF.

Moderate confidence in remaining TAFs due to the uncertainty of
flight cat changes.

There is a 20% chance KPRB remains VFR thru 04Z, and a 20% chance
of LIFR-IFR cigs after 04Z.

There is a chance for VLIFR conds at KSMX (40%) and KSBP (30%)
between through 16Z and again after 03Z.

For coastal sites south of Point Conception, cigs may scatter and
reform, as well as fluctuate between IFR and MVFR through 16Z.
Cigs may return Sunday as IFR.

There is a 30% chance of IFR cigs at KVNY and KBUR through 16Z,
and a 20% chance of remaining VFR through the period.

KLAX...Moderate confidence in TAF. Cigs may scatter and reform
through 16Z. Cigs may fluctuate between BKN008-010 through 16Z,
then lift to BKN018-022 and scatter by as early as 16Z or as late
as 20Z. No significant east wind component expected.

KBUR...Moderate confidence in TAF. There is a 30% chance of
BKN008 cigs through 16Z, and a 20% chance of remaining VFR through
the period.

&&

.MARINE...
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21/403 AM.

For the Outer Waters (Central coast south to San Nicolas
Islands), high confidence in winds and seas remaining below Small
Craft Advisory (SCA) level thru Wednesday. There is a 20-30%
chance of SCA level wind gusts late Wednesday afternoon and
evening for the waters south of Point Conception.
Looking out ahead to Thursday and Friday, there is the potential
for widespread SCA level winds with building steep seas.

For the inner waters along the Central coast, high confidence in
conds remaining below advisory levels through Wednesday.

For the Inner waters south of Point Conception, moderate to high
confidence in conditions remaining below SCA levels through
Wednesday. There is a 20% chance of gusts to 20 kt in the San
Pedro Channel Sunday afternoon. Additionally, there is a 20%
chance of SCA level winds across the western portions Wednesday
afternoon.
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&&

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

$$

PUBLIC...Hall
AVIATION...Lund
MARINE...Lund
SYNOPSIS...Hall

weather.gov/losangeles

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