000
FXUS66 KLOX 091302
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
602 AM PDT Fri Jun 9 2023

.SYNOPSIS...09/341 AM.

Weak high pressure aloft will bring some warming today with a mix
of clouds and sun. Isolated mountain showers and thunderstorm are
possible again this afternoon and evening. A cool, showery, and
unsettled weather pattern will develop through the weekend as
another low pressure system will move over the region. A warming
trend should develop for next week, but temperatures should still
remain below normal as onshore flow remains across the area.

&&

.SHORT TERM (TDY-SUN)...09/337 AM.

The latest fog product shows clouds becoming well entrenched over
the northern areas, while clouds are little muddled inside the
southern California bight and across the Southland. The shortwave
ridge axis aloft is moving ashore along the Central Coast and
will move over the area this morning. This should strengthen the
marine inversion later this morning and allow for low clouds and
fog to fill in south of Point Conception. Onshore pressure
gradients are already starting to strengthen this morning despite
the ridge axis sitting just west of the area. Clouds will likely
struggle to clear from the land mass today, especially the coastal
areas. A partly to mostly cloudy day is shaping up for today, but
if one wants to see sun, one should head farther inland or into
the desert this afternoon.

Southwest flow aloft will develop on the heels of the ridge this
afternoon. Strong onshore flow and a deep marine layer depth will
develop as another low pressure system will move over the region
through the weekend. A mostly cloudy period is shaping as low
clouds from the deep marine layer depth will fleece the area over
the next several days. A solid cloud deck is seen on the fog
product imagery well off the coast of California and these clouds
should push into the region over the weekend. Temperatures
remain on the cooler side of guidance and NBM values as the
mostly cloudy days will inhibit daytime heating and keep
daytime highs well below normal. EPS member solutions suggest a
extended period of cloudy conditions for a majority of coastal and
valley locations over the weekend, possibly extending into the
Antelope Valley.

Drizzle or light rain is possible during the late night and
morning hours through weekend, then the instability with the
trough will destabilize the atmosphere to develop isolated to
scattered showers and thunderstorms over the area. PoPs were
tweaked some from the previous forecast and mentions of morning
drizzle were added across the Southland early Saturday morning,
but the general theme is still present. High-resolution multi-
model ensemble members continue to suggest afternoon and evening
showers and thunderstorms through the early portion of the short-
term period. A vast majority of EPS, GEFS, and CMC member
solutions suggest accumulating precipitation at airports across
southwestern California for periods during the weekend either
from drizzle or light rain, or showers and thunderstorms. CMC
ensemble members continue advertise the best instability with
surface-based CAPE means between 600-1200 J-kg of CAPE developing
between Saturday and Sunday for KSDB, KWJF, and KPMD. While there
is still some uncertainty due to timing and amounts, amounts, if
any, will be quite variable due to the convective nature of the
system. Some areas could receive brief heavy downpours in
thunderstorms, while other areas could see trace amounts due to
drizzle.

.LONG TERM (MON-THU)...09/332 AM.

The low pressure system will exit the region between Monday and
Tuesday, but NAEFS surface pressure gradients keep moderate-to-
strong onshore flow in place across the region. EPS, GEFS, and
CMC ensemble members all suggest a warming trend developing for
much of next week, but it will be moderated along the coast. EPS
members keeps near persistent daytime highs at KOXR and KSBA with
clouds lingering through the day. Below normal temperatures are
expected through much of next week with continued night through
morning low clouds and fog. There is a moderate-to-high chance
that clouds will struggle to clear from the beaches, but the
valley areas will likely see better clearing with some warming.
There is a moderate chance that KPMD and KWJF could see
temperatures closer to normal for late next week.

&&

.AVIATION...09/1302Z.

At 1230Z, the marine layer was about 2500 feet deep. The top of
the inversion was 5000 feet with a temperature of 13 degrees
Celsius.

Clouds were more organized in nature this morning and clouds were
widespread in most coastal and valley zones, pushing into the
lowest coastal slopes. Conds were mostly MVFR to locally IFR,
except IFR to VLIFR in the foothills. Clearing will be slow today.
It will likely remain mostly cloudy through mid to late morning
in the valleys, and early afternoon across the coastal plain.
Clouds may linger at the beaches through the day.

Expect a very similar low clouds pattern tonight, widespread in
coastal and valley areas, and mostly MVFR to locally IFR, except
IFR to VLIFR in the foothills.

KLAX...Moderate confidence in 12Z TAF. There is a 30% chance that
skies will not clear today. No significant easterly wind
component is expected.

KBUR...Moderate confidence in 12Z TAF. There is a 30% chance that
cigs will scatter out as early as 18Z. There is a 30% chance that
cigs will arrive as early as 05Z this evening.

&&

.MARINE...09/545 AM.

For the coastal waters, generally high confidence in the forecast
the winds and seas will remain mostly remain below Small Craft
Advisory (SCA) levels thru Tuesday. However, there is a 30% chance
of SCA level winds across the outer waters Saturday afternoon and
night, and a 20% chance of SCA level winds Saturday afternoon and
night north of Pt Sal and in western portions of the SBA Channel.

There is a slight chance of thunderstorms across the coastal
waters Saturday thru Sunday. Any thunderstorms that develop would
be capable of producing brief heavy rain, gusty winds, small hail
and dangerous cloud to surface lightning. Also, waterspouts could
be possible.

&&

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

&&

$$

PUBLIC...Hall
AVIATION...DB
MARINE...RAT/DB
SYNOPSIS...Hall

weather.gov/losangeles

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