Conejo Valley Station Thousand Oaks Post Office, California Weather Forecast Discussion

271
FXUS66 KLOX 081039
AFDLOX
Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
339 AM PDT Mon Sep 8 2025
Updated aviation and marine sections
.SYNOPSIS...08/145 AM.
A significant cooling trend will begin today as a low pressure
system approaches northern California. This will result in much
cooler temperatures across Southwest California by Wednesday and
Thursday. In addition, marine layer clouds will expand across
coastal areas and well inland over the valleys. A small warming
trend is then expected Friday into the weekend.
&&
.SHORT TERM (TDY-WED)...08/257 AM.
An upper low will move into Nrn CA today and then will sit and
spin through Wednesday while deepening slightly. Flow over Srn CA
will be more and more cyclonic. Hgts will start out at 590 dam
today but will steadily fall to 580 dam by Wednesday. Onshore flow
will prevail through the period both to the north and east (There
might be a few hours of weak offshore flow from the north in the
mornings).
Low clouds and fog will increase in depth coverage and penetration
each day as the cyclonic flow lifts the marine layer steadily
through the period. The marine layer is about 1000 ft deep now but
will be over 3000 ft Wednesday. Currently the low clouds are
confined to the Central Coast and the Paso Robles area. It is
likely (70 percent chc) but not definite that low clouds will
develop across the LA/VTA csts towards dawn. The best lift will
occur Wednesday morning and drizzle if possible across all csts
and vlys.
The lowering hgts and deepening marine layer will team up to bring
a three day cooling trend to the area. Most areas will see 3 to 6
degrees of cooling today, followed by 2 to 4 degrees of coastal
cooling and 5 to 10 locally 12 degrees of cooling in the vlys (due
to the marine layer penetration). Wednesday will be cooler still
with another 2 to 5 degrees of cooling possible. Vly in the upper
80s to mid 90s today will end up in the upper 70s to mid 80s on
Wednesday. Wednesday`s max temps in the vlys will be 10 to 15
degrees blo normal.
There will be Sundowners each night as the NW winds across the
outer waters increase. A wind advisory valid from 5pm late this
afternoon to 5am Tuesday morning has been issued for the western
portion of the SBA south coast. Advisory level gusts are also
possible in the same area Tuesday night.
.LONG TERM (THU-SUN)...08/1231 AM.
On thursday the upper low will rotate out of Nrn CA and into Srn
CA with hgts falling to 577 dam (10 dam blo normal). Once again
there will be plenty of morning low clouds and maybe some more
drizzle. Max temp will continue to run 3 to 6 degrees blo normal
at the csts and 5 to 10 degrees blo normal in the vlys. The vlys
will only see max temps in the upper 70s to mid 80s.
The upper low will move out on Friday. The day will, again, start
out cloudy across he csts/vlys but the clearing will be a little
faster. Slightly higher hgts and slightly faster clearing will
bring 1 or 2 degrees of warming to the area.
A weak ridge will ride over the area on Saturday boosting hgts up
to 585 dam. There will not be much change in the onshore flow, but
the higher hgts may shrink the marine layer enough to keep it out
of most of the vlys. Clearing will be noticeably faster. Max
temps will respond with 2 to 4 degrees of warming bringing a few
readings in the lower 90s to the warmest vly locations. Despite
the 2 days of warming max temps will end up 2 to 4 locally 6
degrees under normals.
Not much change slated for Sunday as a weak trof flattens the
ridge but does not affect the hgts much at all.
&&
.AVIATION...08/1019Z.
Around 0715Z, the marine layer depth was around 700 feet deep at
KLAX. The top of the marine inversion was near 1500 feet with a
temperature around 25 degrees Celsius.
Low-to-moderate confidence exists in the current forecast for
coastal and valley terminals. High confidence exist in the current
forecast for desert terminals. Higher confidence is placed with
terminals north of Point Conception with lower confidence for
terminals south of Point Conception.
LIFR to IFR conditions will continue at terminals north of Point
Conception through at least 16Z, or as late as 18Z. There is a
moderate to high chance of LIFR to IFR conditions at coastal
terminals south of Point Conception through similar times. An
early return of low clouds should occur along the Central Coast
with IFR to MVFR conditions arriving as early as 23Z or as late as
05Z Tuesday. South of Point Conception, IFR to MVFR conditions
could arrive at coastal terminals as early as 02Z Tuesday or as
late as 08Z Tuesday, spreading into valley terminals as soon as
10Z Tuesday or as late as 13Z Tuesday.
KLAX...There is a 30 percent of VFR conditions continuing through
03Z Tuesday. Highest confidence exists in any LIFR to IFR
conditions arriving between 12Z and 14Z, and lingering through 16Z
or 17Z. Conditions should be one category higher tonight with IFR
conditions arriving as soon as 02Z or as late as 08Z. Any easterly
winds should be less than 7 knots.
KBUR...VFR conditions are expected through at least 10Z Tuesday.
No wind impacts are expected at this time.
&&
.MARINE...08/338 AM.
For the waters west through northwest of Point Sal including the
nearshore waters along the Central Coast, winds and seas should
remain below Small Craft Advisory (SCA) levels through early
Wednesday, but there is a moderate-to-high (30-50 percent) chance
of SCA level winds on Tuesday afternoon and evening. By Wednesday
evening, there is a high-to-likely (50-70 percent) chance of SCA
level northwest winds developing and lingering at times into at
least Saturday.
For the waters south through west of the Point Sal and outside the
southern California bight, there is a likely (60-80 percent) chance
of SCA level northwest winds through at least Saturday. The
highest chance of SCA level winds will occur between Wednesday
evening and Friday morning from around Point Conception south to
San Nicolas Island.
Inside the southern California bight, there is a high-to-likely
(50-70 percent) chance of SCA level west winds each afternoon and
evening through Wednesday night, then a moderate-to-high (30-50
percent) chance each afternoon and evening through the remainder
of the week. There is a high (40-50 percent) chance of widespread
SCA conditions developing each afternoon and evening across the
Santa Barbara Channel, with the highest chance of widespread SCA
on Tuesday afternoon and evening.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect from 6 PM this evening to 5 AM PDT
      Tuesday for zones 349-351. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect from 1 PM this afternoon to 5
      AM PDT Tuesday for zone 650. (See LAXMWWLOX).
     Small Craft Advisory in effect from 3 PM this afternoon to 9
      PM PDT this evening for zone 655. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Wednesday for
      zones 673-676. (See LAXMWWLOX).
&&
$$
PUBLIC...Rorke
AVIATION...Hall
MARINE...Hall
SYNOPSIS...MW/CC
weather.gov/losangeles
Experimental Graphical Hazardous Weather Outlook at:
https://www.weather.gov/erh/ghwo?wfo=lox

NWS LOX Office Area Forecast Discussion