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000
FXUS66 KLOX 182047
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
147 PM PDT Thu Apr 18 2024

.SYNOPSIS...18/127 PM.

Strengthening onshore flow beneath southwest flow aloft will
bring a cooling trend through Friday with more extensive night
through morning low clouds and fog. A warming trend is expected
over the weekend as weak ridging aloft builds in. A significant
cooling trend with a deep marine layer depth is on tap for the
middle-to-late portion of next week.

&&

.SHORT TERM (TDY-SUN)...18/141 PM.

A weak trough will remain over California through Friday
maintaining cooler temperatures and a deepening marine layer
across coast and valleys during the night and morning hours. The
marine layer was fairly shallow this morning with dense fog near
the coast. As the marine layer deepens today and tonight, cloud
bases will rise across, leading to less fog near the coast but
increasing fog in the valleys, possibly dense at times, especially
near the hills. With a deeper marine layer in place Friday, likely
in the 2500 foot range, clouds will take a little longer to clear
but full clearing is expected in all areas except possibly some
beaches, especially from Malibu west. Additional cooling expected
Friday as well with most areas in the 60s to low 70s.

Some additional deepening expected Friday night as well, however
weak ridging is expected to move into the area Saturday along with
weakening onshore flow that should lead to earlier clearing and
warmer temperatures in most areas. Much less stratus expected
Sunday with much warmer temperatures, likely the warmest day for
at least a week if not longer with mid 80s in the valleys and mid
to high 70s for coastal areas away from the immediate coast.

.LONG TERM (MON-THU)...18/149 PM.

Ridging will weaken Monday as a trough approaches from the west.
The trough will be the dominant player next week keeping
temperatures below normal starting Tuesday and lasting into the
following weekend. Ensemble solutions have been hinting at some
light rain chances the latter half of the week but the best
chances seem to be next Friday which is still outside the current
7 day forecast window. The first trough comes through Wednesday
and some drizzle can`t be ruled out that morning. Otherwise, just
much cooler temperatures with highs mostly in the 60s. Strong
onshore flow expected most of the week, meaning a steady does of
marine layer stratus for coast and valleys, later than usual
clearing, and gusty winds across the interior, especially later in
the week.

&&

.AVIATION...18/1832Z.

At 18Z, the marine layer at KLAX was about 1800 ft deep. The top
of the inversion was at 4000 ft with a temp of 16 deg C.

Lots of high clouds across the region today with stratus lingering
near the coastline. Low clouds will return to coastal terminals
early this evening, then push into the valleys around midnight.
Conds will be mostly IFR, with some LIFR possible in the valleys,
then improve to MVFR later tonight into Friday morning at coastal
areas.

KLAX...Moderate to low confidence in the 18Z TAF. There is a 30%
chance that cigs will arrive this evening as early as 00Z. Cigs
likely (>60% chance) IFR early then rising to MVFR overnight,
possibly as early as 08z. Any east wind component should remain
less than 6 knots.

KBUR...Moderate confidence in the 18Z TAF. CIGS will return by
08z, and a 30% chance as early as 05z. There is a 20% chance that
cigs will not arrive tonight until 09Z or later.

&&

.MARINE...18/1227 PM.

High confidence in conditions remaining below Small Craft
Advisory (SCA) levels thru Saturday morning. SE winds around 10
knots should occur each morning from the SBA Channel southward to
San Mateo Point. Locally stronger SE gusts are possible thru the
Anacapa Passage and San Pedro Channel.

NW winds will likely reach SCA levels in the outer waters Saturday
afternoon through Sunday, and across the inner waters north of
Point Sal and the Santa Barbara Channel during the
afternoon/evening hours over the weekend. These winds will build
short period seas over all waters. There is a 30% chance of SCA
conditions in the outer waters Monday.

&&

.BEACHES...18/551 AM.

A long-period southerly swell cause elevated surf of 3 to 5 ft
with local sets to 6 or even 7 ft on south-facing beaches of L.A.
County, Catalina Island, and possibly VTU County. There will be a
high risk of rip currents on most beaches today.

&&

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

&&

$$

PUBLIC...MW
AVIATION...MW
MARINE...DB/RK
BEACHES...DB
SYNOPSIS...Hall

weather.gov/losangeles

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