South El Monte, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

234
FXUS66 KLOX 010505
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
1005 PM PDT Wed Apr 30 2025

.SYNOPSIS...30/136 PM.

A deep marine layer and onshore flow will keep temperatures well
below normal through Thursday with some night and morning drizzle
possible across coast and valleys. There is a chance of
thunderstorms in the mountains on Thursday as an upper low moves
through the area. Some warming expected Friday before much cooler
temperatures return over the weekend with a chance of showers at
times.

&&

.SHORT TERM (WED-SAT)...30/715 PM.

***UPDATE***

Latest satellite and surface observations indicate widespread
stratus clouds across the coastal plain with some scattered high
clouds drifting overheard. Current sounding data indicates marine
inversion ranging in depth from 2500 feet north of Point
Conception to around 1800 feet across the LAX Basin. Southwesterly
winds, gusting 25-35 MPH, currently observed across the Antelope
Valley and adjacent foothills.

Forecast-wise for the immediate short term, no significant issues
are expected. Still expecting the marine inversion to deepen
overnight in response to the upper low drifting closer. So,
clouds should push well inland later tonight and Thursday morning.
Otherwise, some scattered mid/high level clouds will drift
overhead. Current southwesterly winds across the Antelope Valley
and adjacent foothills should diminish later this evening.

Overall, current forecast has good handle on the immediate short
term. So, no significant updates are expected.

***From Previous Discussion***

An upper low is moving slowly south along the coast and is
deepening the marine layer. Clouds managed to clear across most of
the valleys but is struggling near the coast, especially from
Malibu north. Temperatures dropped several degrees as a result.

Additional deepening of the marine layer is expected tonight and
Thursday as the upper low moves closer and temperatures aloft
cool. This may be enough to generate some drizzle across coast and
valleys. And likely an even slower clearing day as well with
cooler temperatures, especially in areas that got sunshine today.

With the upper low moving into the area Thursday the air mass will
become increasingly unstable leading to at least a 30-50% chance
of thunderstorms over the mountains, with a 20-30% chance of
those storms moving off into some of the valleys, particularly
those north of Pt Conception. PW`s are unusually high tomorrow
and this combined with the instability and also very slow steering
flow there is higher than usual chance for flooding near any
storms that develop. Latest thinking is that rain rates between a
half and one inch per hour are possible with this storms, and
also some small hail and gusty winds. Burn scars in or near the
mountains (not including the Santa Monicas) should pay close
attention to the weather Thursday afternoon and be prepared to
take action should storms develop.

The upper low is expected to shift southeast Thursday night into
Friday with weak high pressure developing. As such chances for
additional storms are under 10%. Forecast soundings indicate some
lowering of the marine layer with better chances for afternoon
clearing and slightly warmer temperatures.

Another upper low will be moving into northern California Saturday
afternoon and into southern California Saturday night into Sunday.
Chances for showers will be increasing during this period,
especially near and over the mountains.

.LONG TERM (SUN-WED)...30/456 PM.

Mdls and ensembles are in good agreement for an unusual May
weekend weather event. A cold (~550 dam) upper low will sweep
into the state on Saturday and over Srn CA on Sunday. A wave of
PVA will go over the area and will bring a 20 to 30 percent chc
of showers to the mtns in the afternoon. There is not much
moisture to work with and any rainfall amounts will be light. In
addition to the persistent low clouds there will be partly to
mostly cloudy skies from mid and high clouds assoc with the upper
low. Strong ~8 mb onshore flow to the east will keep many beaches
swaddled in low clouds all day as well as bringing near advisory
wind gusts to the Central Coast, mtn tops and the wester Antelope
Vly as well as its foothills. Coastal temps will fall 2 to 4
degrees but the rest of the area will 4 to 8 locally up to 12
degrees of cooling. This cooling will bring max temps across the
csts down into the 60s with vlys falling into the mid 60s to
lower 70s.

The upper low will move over Srn Ca on Sunday. Hgts will fall to
~552 dam. The upper low will bring plenty of cold air aloft for
some decent instability but the system is pretty moisture starved
and there will only be a 20 to 30 percent chc of mtn showers and a
less than 10 percent chc of a TSTM. Skies will be partly to mostly
cloudy through the day. Max temps will be the main talking point
with 4 to 8 degrees of cooling across the csts and vlys and 8 to
15 degrees across the mtns and far interior. These cold
temperatures will allow snow to fall to as low as 5500 ft. It will
feel like a colder than normal January day with max temps coming
in a few degrees either side of 60 for the csts.

Enough ensemble members swing a secondary impulse across the area
Monday as the main upper low exits the state. This is enough for a
slight chc of mtn shower, but again without much moisture to work
with the shower threat is very minimal. All the cold air should
have mixed out the marine inversion so there should be few if any
low clouds in the morning. Skies still partly cloudy from some
wrap around clouds. 2 to 5 degrees of warming across the csts and
vlys will not be enough to bring max temps out of the 60s.

The mdls and ensembles diverge on Tuesday. Whatever the outcome it
will be low impact dry day. There will either be slight warming
(EC) or substantial warming (GFS)

***

A note from WFO Oxnard Lead Meteorologist D Bruno:

Today is a bittersweet day for me. After nearly 35 years in this
wonderful agency, I am retiring from the National Weather Service
today. After beginning my career in my hometown of Boston in 1990,
I moved to the Southland, taking a job at the NWS Los Angeles
area office in Oxnard. I planned to return back to Boston to be
near family, but I fell in love with southern California, so I
happily stayed...for three decades and counting.

I have loved all things weather since I was about 5 years old. My
job as a Lead Meteorologist in the National Weather Service has
been a dream come true. I have been so fortunate to work with
such a amazing group of kind, professional, knowledgeable and
dedicated people during my career. I would like to bid a fond farewell
to all of my coworkers (including those who have moved away), and
to our incredible partners in the media, emergency management and
fire communities. I will miss you all, and I will miss the job,
but I look forward to relaxing times and seeing more of this
beautiful world in my next phase of life. Thank you southern
California, You are in good hands with the top-notch staff at NWS
Oxnard!

DB--forecaster number 11

&&

.AVIATION...01/0203Z.

At 2045Z at KLAX, the marine layer was 1700 feet deep. The top of
the inversion was roughly 2800 feet with a temperature of 17 C.

High confidence in TAFs for KWJF and KPMD.

Moderate confidence in TAFs for remaining sites. MVFR to IFR cigs
will return to all sites, with a 20-30% chance for LIFR
conditions for KSBA, KSMX, KSBP, and KBUR. Minimum flight cat may
be off at one at any point, and flight cat changes may be off +/-
3 hours.

KLAX...Moderate confidence in TAF. Good confidence in MVFR cigs
overnight, with moderate confidence in afternoon clearing. No
significant east wind component expected.

KBUR...Moderate confidence in TAF. Arrival of cigs tonight could
be off +/- 2 hours. There is a 30% chance for cigs OVC003-005
and/or vsbys 1-3SM.

&&

.MARINE...30/1003 PM.

In the outer waters, high confidence in winds and seas remaining
relatively benign through Thursday. Small Craft Advisory (SCA)
winds and seas (with swells up to 15 ft) are likely (>80% chance)
Fri afternoon thru Sun night, with a 60-70% chance of GALE force
winds Sat afternoon/night. During this time, there is also a less
than 10% chance for Storm Force winds (48 kts).

In the inner waters north of Point Sal, SCA conditions are not
expected thru Fri morning. SCA winds and seas are likely (70%
chance) Fri through Sun, with highest chances in the
afternoon/night hours. There is a 60% chance GALES Sat
afternoon/night.

In the Santa Barbara Channel, SCA conds are not expected thru Fri
morning. SCA winds and seas are then likely (70% chance) Fri
afternoon through Sun night, with a 40-50% chance of GALES across
western sections and for the Channel Islands Sat afternoon/eve.

In the southern inner waters, SCA conds are not expected thru
Sat morning, then are likely (70% chance) beginning in the the
afternoon Sat and continuing thru Sun night. There is a 40-50%
chance for GALES in the western portion of the zone and a 30%
chance for GALES for the nearshore waters north of Point Dume Sat
afternoon/night.

There is a 10 percent chance of thunderstorms across the northern
waters Saturday and most of the coastal waters into Sunday.

&&

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

&&

$$

PUBLIC...MW/Thompson
AVIATION...Phillips
MARINE...Phillips/Lewis
SYNOPSIS...MW

weather.gov/losangeles

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