Valencia, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

473
FXUS66 KLOX 160513
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
1013 PM PDT Tue Apr 15 2025

.SYNOPSIS...15/1012 PM.

Strong onshore flow and a deep marine layer will bring plenty of
night through morning low clouds and fog this week. There will
also be a chance of drizzle each morning. Partly to mostly cloudy
skies will occur Thursday and Friday with a chance of showers and
a slight chance of a thunderstorm with the best chance over the
mountains and far interior. Dry and warmer conditions are
expected for the weekend into early next week.

&&

.SHORT TERM (TUE-FRI)...15/1009 PM.

***UPDATE***

As the upper level low lingers off the southern California Coast
today, temperatures barely warmed for most locations with mid 50s
to mid 60s common throughout the region. This low allowed for the
marine layer to become quite deep, with low clouds reaching far
into the interior of San Luis Obispo County, the Cuyama Valley,
and the Santa Clarita Valley this morning. Following the marine
layer clouds, high clouds also moved in from the nearby low,
contributing to cooler high temperatures. The Antelope Valley rose
to around 80 degrees, thanks to much more sunny conditions.

Looking into tonight, plenty of mid to high level clouds are
streaming into southern California. Low clouds should develop
overnight over about the same areas as the previous night, with
patchy fog and light drizzle possible as the low pressure system
pushes closer. This deep marine layer with a weaker inversion will
likely lead to a reverse clearing scenario Wednesday, valley
areas that struggle to clear may end up a few degrees cooler than
forecast. Otherwise, the forecast looks on track with the
potential for light showers and chance for thunderstorms Wednesday
into Thursday.

***From Previous Discussion***

An upper low about 500 miles west of KLAX will very slowly move
east and begin to move inland near KLAX during the day on
Thursday. As a result, cool and mostly cloudy conditions will
continue for the next couple of days at least. The marine layer
was around 3000 feet deep this morning and will likely deepen as
the low approaches and temperatures aloft cool. This will increase
the chances for drizzle, which may feel more like light rain at
times, especially near the foothills. Given the current trajectory
of the low, drizzle chances will be highest south of Pt
Conception, but can`t rule it out across SLO and northern Santa
Barbara Counties. Also can`t rule out a brief thunderstorm across
the northern Ventura or Santa Barbara mountains Wednesday
afternoon with some cooling aloft destabilizing the air mass in
that area.

As the marine layer deepens it will eventually reach a point where
coastal areas can no longer support a solid cloud layer, leading
to a reverse clearing situation where valleys stay socked in while
coastal areas start to see more sunshine. This could happen as
early as Wednesday. In any case, temperatures will remain at least
4-8 degrees below normal and possibly as much as 15 degrees below
normal in the valleys with highs only in the low to mid 60s.

As the low moves onshore Thursday drizzle/light rain chances will
increase south of Pt Conception with amounts up to around a tenth
of inch near the coast and as much as a quarter inch in the south
facing foothills. With strong onshore flow in place some low end
advisory level southwest winds are possible across the Antelope
Valley.

A second upper low is expected to drop down out of Canada and
through the Great Basin Friday maintaining the deep marine layer
and drizzle/light rain chances, again mostly south of Pt
Conception. Models have shifted the track of this upper low a
little farther east with not as much instability aloft as earlier
model solutions had shown, so chances for thunderstorms locally
are lower but not zero.

.LONG TERM (SAT-TUE)...15/135 PM.

A warming trend will begin Saturday as both upper lows shift
quickly east and weak high pressure develops behind it.
Temperatures for coast and valley areas will still be below normal
but only by a few degrees with highs ranging from the mid to high
60s at the coast to mid to upper 70s inland. Overall a very low
impact weather pattern through at least the middle of next week
with the only potential hazard being some gusty winds across the
far interior areas during the afternoon and evening.

&&

.AVIATION...16/0239Z.

At 00Z at KLAX, the marine layer was 2400 ft deep, with an
inversion top at 5600 ft and a maximum temperature of 12 C.

Moderate confidence in TAFs. Cigs arrival times may be delayed by
2-3 hours. Expecting widespread MVFR cigs for most sites tonight
into Wed AM except for at KPMD and KWJF. A reverse clearing
pattern is expected Wed, meaning lower confidence in clearing
times for KVNY and KBUR.

KLAX...Moderate confidence in TAF, with some uncertainty in the
arrival time of cigs, which could be delayed by 2-3 hours. No east
wind component is expected.

KBUR...Moderate confidence in TAF. Lower confidence in clearing
times Wed and cigs may be in and out of the TAF site through the
day Wednesday.

&&

.MARINE...15/743 PM.

Overall, high confidence in current forecast. There is a 10-20%
chance of Small Craft Advisory (SCA) level winds south of Pt.
Conception and around Northern Channel Islands on Fri and Sat.
Otherwise, conditions are expected to remain below SCA levels
through Sunday morning.

&&

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

&&

$$

PUBLIC...Phillips/MW
AVIATION...Phillips
MARINE...Black
SYNOPSIS...LP/MW

weather.gov/losangeles

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