000
FXUS66 KLOX 190615
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
1115 PM PDT Thu Apr 18 2024

.SYNOPSIS...18/827 PM.

Strengthening onshore flow will bring a cooling trend to most
areas through Friday, along with more extensive night through
morning low clouds and fog. A warming trend is expected over the
weekend as weak ridging builds in aloft. A significant cooling
trend with a very deep marine layer is expected starting Tuesday
and persisting through late next week.

&&

.SHORT TERM (TNT-SUN)...18/827 PM.

***UPDATE***

A slightly cooler day across the area today, especially along the
Central Coast where a stubborn marine provided only brief clearing
during the afternoon hours. Peak highs were near 80 in the
valleys, with low 80s observed in the Antelope Valley.

Expect further cooling of about 3 to 5 degrees for most places
tomorrow with highs in the 60s and 70s. A weak upper trough will
swing across the area, helping to spin up a deepening marine layer
that will push farther inland tonight into early Friday. Low
clouds could extend through San Luis Obispo County to the eastern
border overnight. This layer will likely be slow to clear,
similarly to today, with a chance of reverse clearing over the
beaches. Due to higher ceilings, the beaches won`t see much fog,
with there will be areas of fog affecting many foothill locations.

***From Previous Discussion***

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...19/0615Z.

Around 0530Z, the marine layer depth was about 1400 ft deep at
KLAX. The top of the inversion was near 3200 feet with a
temperature at 15 degrees Celsius.

Moderate confidence in the current forecast. Higher confidence in
flight categories. Lower confidence in timing.

Sub-VFR conditions at coastal terminals should improve one
category between through 13Z. There is a moderate chance of VLIFR
conditions at terminals north of Point Conception between 07Z and
13Z. Conditions should improve to MVFR between 15Z and 18Z. A
later clearing is expected on Friday. There is a moderate chance
that all coastal terminals may not clear at all.

KLAX...MVFR conditions are likely through at least 20Z. Ceilings
will lift above 2000 feet between 15Z and 20Z. There is a
40 percent chance of VFR conditions developing between 22Z and
02Z. If VFR conditions develop, an early return of MVFR
conditions should be expected with an arrival between 02Z and
04Z.

KBUR...IFR conditions will spread into KBUR between 08Z and 10Z,
then lift one category between 13Z and 15Z. There is a 10 percent
chance of VLIFR conditions developing around arrival until as late
as 10Z. VFR conditions should develop between 18Z and 20Z with a
30 percent chance of ceilings at or below 5000 feet lingering
through the afternoon.

&&

.MARINE...18/833 PM.

High confidence in conditions remaining below Small Craft
Advisory (SCA) levels thru Saturday morning, except for localized
SCA level NW-W winds south of Point Conception Friday afternoon
and evening. 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.

&&

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

&&

$$

PUBLIC...MW/Smith
AVIATION...Hall
MARINE...RK/Schoenfeld
SYNOPSIS...Hall/Smith

weather.gov/losangeles

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