Sun Valley, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

639
FXUS66 KLOX 170522
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
1022 PM PDT Wed Apr 16 2025

.SYNOPSIS...16/122 PM.

Skies will be partly to mostly cloudy through Friday with a chance
of light rain or drizzle at times. Temperatures will remain well
below normal. Warmer temperatures are expected Saturday through
the middle of next week but still 3 to 6 degrees below normal
across the coast and valleys.

&&

.SHORT TERM (WED-SAT)...16/1020 PM.

***UPDATE***

Temperatures were cool today due to a very deep marine layer (6700
ft this evening). Clouds lingered over many valleys and mountains,
and failed to clear through the day. The onshore LAX-DAG gradient
peaked around 9.4 mb this afternoon, contributing to gusty
southwest winds for the Antelope Valley and foothills. Quite a few
areas gusted into the 50s, especially near the Hwy 14 Corridor. A
wind advisory was issued this evening for these areas, as gusty
winds should continue through tonight into Thursday night.

Tonight, a chance for isolated to scattered showers develops as
the low center begins to move southeast directly over southern
California. Chances will last through Thursday, and were expanded
to include the north slopes as suggested by a variety of
guidance. The potential for thunderstorms still looks too low to
add to the forecast. Will start seeing decreasing clouds and a
warming trend as the low finally moves east of the area and high
pressure builds.

***From Previous Discussion***

A classic reverse clearing day today south of Pt Conception as the
marine layer depth approached 6000 feet. Not quite as solid a
stratus layer across SLO and northern Santa Barbara Counties but
plenty of clouds there as well in addition to well below normal
temperatures. Onshore gradients are over 8mb to the desert this
afternoon and that is generating some gusty winds through the
Highway 14 corridor and into the Antelope Valley.

Going forward, the cloud forecast will certainly be a challenge
with still a deep marine layer in place but a rapidly weakening
inversion as the upper low moves through the area with cooler air
aloft. Already seeing a preview of this over the coastal waters
today, and expect the next couple days will be a hodge-podge of
clouds, some clearing at times, and even some light rain or
drizzle chances, especially Thursday into Thursday night across
LA/Ventura Counties. NBM pops have consistently been notably low
for Thu/Fri while virtually all the EPS and many of the GEFS
ensemble solutions have consistently shown light rain or drizzle
with amounts mostly under a tenth of an inch. This latter solution
seems reasonable given the upper low moving through the area
tomorrow generating some mild upward motion and making efficient
use of the 0.9" PWs in place. Temperatures will remain several
degrees below normal with highs mostly in the 60s.

A second upper low will come through the region Friday, though
this one is taking a more inside slider track through NV/AZ so
chances for any precip are lower than Thursday but not zero. Best
chances would be across across eastern LA County and again mostly
just very light precip. And again much cooler than normal
temperatures.

A weak high pressure ridge will move into the state Saturday
leading to several degrees of warming in all areas but especially
inland.

.LONG TERM (SUN-WED)...16/155 PM.

Good agreement with the deterministic and ensemble mdls for the
extended fcst. All signs point to at least 4 days of benign
weather. The upper low will push to the east on Saturday and weak
ridging and/or dry NW flow will set up over the state. Moderate to
strong onshore flow will occur all 4 days. The marine layer
stratus pattern will slowly redevelop as well. Max temps will warm
each day Sat through Mon. The biggest jump in temps will occur
Saturday. By Monday max temps will be 2 to 4 degrees blo normal
across the csts/vlys but will have risen to 3 to 6 degrees above
normal across the interior. Max temps will cool Tuesday as hgts
fall ahead of a trof. The moderate onshore push to the east will
bring gusty afternoon winds to the Antelope Vly and foothills.

&&

.AVIATION...16/2356Z.

At 2320Z at KLAX, the marine layer was around 6700 ft. The top of
the inversion was at 8500 feet with a temperature of 4 C.

Overall, moderate to high confidence in 00Z TAF Package. Some
terminals will see a brief window of clearing thru at least 03Z
Thu before VFR ceilings (383. (See LAXNPWLOX).
PZ...NONE.

&&

$$

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

weather.gov/losangeles

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