Walnut, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

993
FXUS66 KLOX 011750
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
1050 AM PDT Sun Jun 1 2025

.SYNOPSIS...01/225 AM.

There is a chance of a shower or thunderstorm today over LA county
and to a lesser degree Ventura county. Otherwise, look for night
through morning low clouds and fog to continue through the week.
It will be cooler today and Monday with a warming trend starting
on Tuesday.

&&

.SHORT TERM (TDY-TUE)...01/1048 AM.

The latest infrared imagery indicates an upper-level trough off
the Baja California coast this morning. Some convection and
lightning strikes can seen moving northward over the spine of
northern Baja California. While showers and thunderstorms are
still possible this afternoon and evening, the convective
parameters are a little weaker versus Saturday. The best chance
for showers and thunderstorms will be over the San Gabriel
Mountains this afternoon and evening. With the counterclockwise
circulation on the back side of the trough, a stray shower or
thunderstorm drifting into the San Gabriel Valley cannot be ruled
out entirely.

The middle and high level debris clouds are playing tricks on
the marine inversion this morning, weakening it. As a result, low
clouds and fog are clearing much quicker across the Southland
this morning. To the north from Santa Barbara northward, the
effects of the cloudiness aloft are more muted, hence the clouds
are hanging in a little tougher. Clouds should clear off most of
the land mass by this afternoon, but an early return of low clouds
and fog should be expected at the beaches and immediate coastal
locales. A little less confidence exists in this idea for Los
Angeles County coastal sections due to the possibility of middle
and high clouds continuing to stream over the area.

Another upper-level trough off the North Coast of California will
dig south and drop into the region through Monday. This will keep
strong onshore flow in place over the coming days. Night through
morning low clouds and fog should become more extensive and
expansive through Tuesday. NAM BUFR time height sections indicate
the marine layer depth deepening to between 1200 and 1700 feet
deep tonight and into Monday morning, and then to between 2000
and 2500 feet deep on Monday night and into Tuesday morning. An
eddy circulation in place will likely help to deepen the marine
layer a bit deeper across the Southland. Night through morning
drizzle cannot be ruled out across the Southland late Monday
night and Tuesday morning as the dynamics with the trough start
to move over the region.

With the stronger onshore flow, marginally gusty southwest winds
will develop each afternoon and evening across the Antelope
Valley over the next several days. Advisory level winds are not
expected at this time as onshore pressure gradients do not look
strong enough, but it will be close in some of the foothill
locations.

***From Previous Discussion***

The upper low to the SW continues to spin and will slowly move to
the NE today ending up over Yuma AZ by the evening. Today it will
spin moisture, instability and weak dynamics into the area. This
will bring a chance of showers and or TSTMs to LA county and to
the VTA mtns. The MUCAPE values are lower today and any storms
that form will not be as strong as the storm that formed over the
VTA and SBA mtns ydy. By early evening the low`s eastward push
will drag the chc of rain to the east and only the eastern San
Gabriels will have a chc of a shower. The marine layer has shrunk
to under a 1000 ft and low clouds have formed over most of the
coasts. An easterly push from the upper low`s flow pattern,
however, is pushing some of the low clouds south of Point
Conception off of the csts and into the waters. Skies, otherwise,
will be partly to mostly cloudy due to mid and high level clouds
spinning around the low. The combination of these clouds and
strong onshore flow will lower max temps 4 to 8 degrees. Most max
temps (except for the Central Coast) will still end up a few
degrees above normal.

Another upper low will pirouette down the coast on Monday. It has
very little moisture to work with and will not do much other than
deepen the marine layer some and bring cooling to the area.
Offshore trends in the morning may keep some of the vlys cloud
free but a strong onshore push in the afternoon will likely keep
many west facing beaches cloudy all day. Lowering hgts and strong
onshore flow will combine to lower most temps another 4 to 8
degrees (the Central Coast will only cool 1 to 2 degrees). Most
max temps across the csts/vly will end up in the mid 60s to mid
70s with the warmest vlys coming in with reading in the upper 70s
to 81 degrees.

Look for a robust marine layer in the morning with slow clearing
and likely no clearing for many west facing beaches. Max temps
will not change much and will remain 3 to 6 degrees blo normal.

.LONG TERM (WED-SAT)...01/306 AM.

Not much excitement on tap for the long term. Xtnd mdls agree that
a long wave weak pos tilt trof will settle over NV/CA Wed and
remain in place through at least Saturday. At the sfc mdt to
strong onshore flow both to the east and north will continue each
day. June Gloom will be fully established with low clouds covering
the csts and vlys in the night through morning hours with slow
clearing and likely no clearing for many beaches. Strong onshore
flow to the east will likely bring gusty westerly winds to the
Antelope Vly and western foothills each afternoon.

Mdls are forecasting a slow 1 to 2 degree warm up each day. While
possible this may be a little optimistic as none of the parameters
that affect day to day temps will be changing that much if at all.

&&

.AVIATION...01/1734Z.

At around 18Z at KLAX, there was no recent sounding data
available.

High confidence in VFR TAFs for KPMD and KWJF. There is a 10%
chance for

Low to moderate confidence in remaining TAFs. There is a chance
for VFR conds to prevail through the period at KPRB (40%),
KBUR/KVNY (20%). Otherwise, high confidence in return of marine
layer clouds to all coastal sites early this evening. Moderate
confidence in timing of return (+/- 2 hours), and low confidence
in minimum flight cat, which may be off by one cat from minimum
forecasted. There is a 30% chance KSBA does not clear today.

There is a 20% chc of a shower for LA County sites through 00Z
and ISOLD TSTMs are possible near the mtns 18Z-00Z.

KLAX...Low to moderate confidence in TAF. Arrival time tonight may
be off by +/ 2 hours. There is a 20% chance for OVC003-OVC004 cigs
tonight. There is a 20% chance of a shower through 00Z. Any east
wind should remain under 8 kts.

KBUR...Low confidence in TAF.
There is a 10% chance of a TSTM 18Z-00Z and a 20% chance for a
shower. There is a 20% chance for VFR conds to prevail through the
period. Otherwise, low confidence in minimum flight cat, which
may be off by one cat. Arrival time may be off +/- 2 hours.

&&

.MARINE...01/836 AM.

For the Outer Waters, there is a 40-50% chance of Small Craft
Advisory (SCA) level wind gusts for the western portion of the
northern Outer Waters, around Point Conception, and south to San
Nicolas Island this afternoon into the evening. Additionally,
there is a 50-60% chance for seas to reach or exceed 10 feet in
the western portion of the northern Outer Waters late tonight into
Monday afternoon. Currently holding off on any SCA`s due to the
isolated nature of the wind gusts and seas. Thereafter,
conditions look to remain below advisory criteria through next
week. However, Tuesday evening may see some breezy conditions
south of Point Conception.

For the nearshore waters along the Central Coast, high confidence
in conditions remaining below SCA criteria through the week.
However, there is a 30-40% chance for SCA level wind gusts this
afternoon into the evening over northern portions.

For the Santa Barbara Channel, high confidence in conditions
remaining below SCA criteria through next week. However, there is
a 20% chance of SCA level wind gusts over the western portion and
near Santa Cruz Island during the afternoon and evening hours
today.

For the Inner Waters off the Los Angeles and Orange County coasts,
high confidence in conditions remaining below SCA levels through
next week.

An upper level low pressure system off the coast of Baja
California will bring a 10-20% chance of thunderstorms through
this afternoon, especially south of the Channel Islands. Anything
thunderstorm could produce lightning, rain, and gusty, erratic
winds.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement in effect through Tuesday afternoon
      for zones 354-362-366. (See LAXCFWLOX).
PZ...NONE.

&&

$$

PUBLIC...Hall/Rorke
AVIATION...Lewis
MARINE...Phillips/Lewis
SYNOPSIS...30

weather.gov/losangeles

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