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000
FXUS66 KLOX 222123
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
223 PM PDT Mon Apr 22 2024

.SYNOPSIS...22/217 PM.

Strengthening onshore flow and a deepening marine layer will
bring low clouds, fog, and drizzle to the coast and coastal
valleys throughout this week. Cool conditions will continue, with
high temperatures several degrees below normal each day this week.
A couple of weather disturbances will track across the area later
in the week, bringing a small chance for light rain showers for
mid to late week.

&&

.SHORT TERM (TDY-THU)...22/222 PM.

Strong onshore pressure gradients will persist through much of
this week. These onshore gradients will further strengthen through
mid-week in response to midlevel ridging focusing the strongest
surface heating over the central Great Basin. Diurnally enhanced
onshore gradients for LAX-DAG are forecast to reach 8-9 mb each
day through Thursday. In addition, for Wednesday night into
Thursday, a midlevel low will progress eastward over the East
Pacific and across southern California. This will further
reinforce and deepen the marine layer over coastal areas and
coastal valleys later this week.

Widespread low clouds and fog are expected to accompany the
deepening marine layer, which will also cool temperatures across
the region. High temperatures are expected to be in the 60s in
most areas each day, except rising into the 70s over the Antelope
Valley away from the marine layer. In addition, the marine layer
will significantly deepen to depths over 2500-3000 feet tonight
into Tuesday and then depths over 4000 feet for Thursday. This
will support drizzle over many areas -- especially during the
evening, overnight, and morning hours. Dry conditions in the mid
and upper troposphere will limit the potential for measurable
rainfall, though a few light showers could accompany the passage
of the midlevel low late Wednesday night and Thursday morning.

.LONG TERM (FRI-MON)...22/227 PM.

Following the passage of the aforementioned midlevel low,
temperatures aloft will cool and onshore pressure gradients will
weaken. These factors will allow the marine layer to lose depth
and weaken to some extent by the end of this week, with the extent
of fog and drizzle correspondingly lessening. Thereafter, further
cooling aloft, decreasing onshore flow, and weakening of the
marine layer will occur with the glancing influence of a deep
midlevel trough amplifying over the Great Basin late Friday into
the upcoming weekend. However, despite the weakening marine layer,
cooling aloft will maintain high temperatures in the 60s in most
areas through Friday. Thereafter, temperatures are expected to
warm a few degrees by Sunday as midlevel heights rise behind the
deeper trough. Regarding precipitation, there will be a slight
chance for light showers Friday into Friday night in conjunction
with the second disturbance glancing the area, which will be
followed by dry conditions.

&&

.AVIATION...22/1806Z.

Overall for the 18Z TAF package, moderate confidence in coastal
and valley TAFs and high confidence in desert TAFs. Lower
confidence for coastal/valley sites due to uncertainties in timing
of flight category changes. For tonight, drizzle is likely for
much of the coast as the marine layer grows, likely bringing IFR
CIGs.

KLAX...Moderate confidence in 18Z TAF. Timing of flight category
changes between IFR and MVFR conditions could be +/- 3 hours of
current forecasts. No significant easterly wind component is
expected.

KBUR...Moderate confidence in 18Z TAF. Development of VFR
conditions could be as late as 20Z. Timing of return of IFR/MVFR
conditions tonight could be +/- 3 hours of current forecasts.

&&

.MARINE...22/129 PM.

For the Outer Waters, moderate to high confidence in current
forecast. Today through Wednesday, high confidence in winds and
seas remaining below Small Craft Advisory (SCA) levels. For
Thursday and Friday, high confidence in winds increasing to SCA
levels with a 40% chance of Gale force winds across PZZ673 and
PZZ676 Thursday and increasing to 70% on Friday. By Friday night
the significant wave height could be in the 10-12` range.

For the Inner Waters north of Point Sal, high confidence in
current forecast. Today through Wednesday, winds and seas will
remain below SCA levels. For Thursday and Friday, about a 40%
chance of winds increasing to SCA levels, mainly in the afternoon
and evening hours.

For the Inner Waters south of Point Conception, moderate to high
confidence in current forecast. Today through Wednesday, high
confidence in winds and seas remaining below SCA levels. For
Thursday, Friday, and into Saturday morning there is a 50-70%
chance of winds increasing to SCA levels, especially across
western sections.

&&

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

&&

$$

PUBLIC...Cohen
AVIATION...jld
MARINE...jld
SYNOPSIS...Cohen

weather.gov/losangeles

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