East San Gabriel, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

028
FXUS66 KLOX 141253
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
553 AM PDT Mon Apr 14 2025

.SYNOPSIS...14/455 AM.

A deep marine layer depth with strong onshore flow will continue
a cooling trend through the work week. Night through morning low
clouds and fog can be expected with drizzle possible each night
and morning. A cold upper level low pressure system is forecast
to bring showers to the area between Thursday night and Friday
night. A thunderstorm cannot be ruled out especially in the
mountains and deserts on Friday. Dry and milder conditions with a
warming trend can then be expected for next weekend.

&&

.SHORT TERM (TDY-WED)...14/500 AM.

Low clouds and fog are well entrenched across the region this
morning as broad upper-level troughing is anchored off the
California coast. Morning drizzle is starting to occur across
portions of the area as upper-level dynamics start to move over
the region. Two cutoff troughs can been seen on satellite imagery
this morning with one trough sitting about 230 miles west-
southwest of Point Conception, and another cutoff low sitting
about 500 miles south-southwest of Point Conception. Both troughs,
rotating around each other in a Fujiwhara effect, will continue
to provide a cooler weather pattern with a deep marine layer and a
threat of night through morning drizzle through tonight.

The southern trough will eject out of the broader circulation
late this afternoon and this evening across Baja California and
into southern California. Then, another trough near 37N and 137W
will drop in and merge with the northern trough, deepenening it as
it approaches the California coast on Wednesday. A cooler weather
pattern is likely to continue into late week, along with a deep
marine layer producing extensive low clouds and fog with night
through morning drizzle. Clearing will be inhibited along the
beaches each day as there is a high to likely chance that clouds
will hug the coast each day into Wednesday and maybe Thursday.

As the trough ejects out to the south of the area this afternoon
and evening, there is a non-zero chance of showers. Shower chances
could increase again on Wednesday as the deeper trough approaches
Point Conception. Quite a bit of dynamics and 500 mb heights
declining to 560 dam are certainly plausible to extend the night
through morning drizzle into later in the day or produce light
showers across the region. While PoPs remain lower than forecast,
moisture and precipitation parameterization schemes in the model
solutions typically struggle with trough circulations and dynamics
to the southwest of the region. NAM BUFR time height sections are
hinting at a deep enough marine layer by Wednesday morning to
turn the marine intrusion into a deep moist layer and continue
the possibility of light drizzle or rain. If NAM BUFR time height
sections are correct, the moist layer could deepen to near 7000
feet by Wednesday night across the Southland. This would be plenty
sufficient to produce showers or light rain.

.LONG TERM (THU-SUN)...14/458 AM.

The upper-level trough will drift over the Southland on Thursday
and bring the possibility of afternoon and evening showers and
thunderstorms. A cooling trend will continue into Thursday and
Friday as much colder air starts to pipe into the area as a trough
in the Gulf of Alaska will move over a ridge in the Pacific
Northwest and dig south down the leading edge. This could provide
an additional shot of colder air aloft to destabilize the air
mass for convective showers to develop. The two troughs will merge
at some point between Thursday and Friday with a colder air mass
being ushered in behind the trough for Friday. While the
instability looks to be best on Friday, showers and thunderstorms
cannot be ruled out on Thursday either.

Gusty winds are possible between Wednesday and Friday across the
Antelope Valley and across the interior portions of the region as
strong onshore pressure gradients approaching 10 mb onshore. EPS
ensemble members indicate gusty winds for KPMD and KWJF, albeit
just shy of advisory levels. Earlier ensemble wind gust means had
much stronger winds. Any change in the troughs direction could
result in much gustier winds across the region.

Cluster analysis continues to agree for a warming trend developing
over next weekend as an upper-level ridge over the North Central
Pacific Ocean will nose into the West Coast. While there are
variations to the ridge in the cluster analysis, all four WPC
clusters would suggest a warming trend developing. A thinner
marine intrusion should be expected with less low cloud coverage.

&&

.AVIATION...14/1253Z.

At 12Z at KLAX, the marine layer was around 2000 feet deep. The
top of the inversion was around 3400 ft with a temp of 17 C.

Clouds were widespread in all coastal and valley areas, except for
the interior valleys of SLO County, the Cuyama Valley, and the
Santa Clarita Valley. Cigs were mostly IFR to LIFR, with local
VLIFR. In southern coastal portions of L.A. County, cigs have
risen into the MVFR category.

Expect skies to clear by mid to late morning in the valleys, and
by early afternoon across the coastal plain. Cigs may linger at
the beaches, especially the beaches of Ventura County and southern
SBA County.

Expect a similar low clouds pattern tonight, but the marine layer
may be slightly deeper. Expect IFR to LIFR cigs in most areas,
except MVFR conds in coastal areas south of Pt Conception, and
VLIFR conds in the foothills and valleys.

KLAX...Low to moderate confidence in the TAF. There is a 20-30%
that IFR cigs will not lift into the MVFR category until 17Z.
There is a 20% chance that cigs will not scatter out at all this
afternoon. There is a 20% chc that cigs will arrive as early as
01Z Tue. E wind component will remain under 7 kt thru the pd.

KBUR...Low to moderate confidence in the TAF. There is a 20-30%
chc that cigs will linger until as last at 20Z. There is a 30%
chc that cigs will arrive as early as 03Z Tue.

&&

.MARINE...14/530 AM.

Small Craft Advisory (SCA) conds are not expected thru Fri night.

&&

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

&&

$$

PUBLIC...Hall
AVIATION...DB
MARINE...DB
SYNOPSIS...Hall

weather.gov/losangeles

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