Agoura, California Weather Forecast Discussion

154
FXUS66 KLOX 221715
AFDLOX
Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
1015 AM PDT Mon Sep 22 2025
UPDATED AVIATION SECTION
.SYNOPSIS...22/912 AM.
Dry conditions with warmer temperatures are expected today.
Monsoon moisture will be increasing tonight into Tuesday
resulting increasing shower and thunderstorm chances that will
continue into at least Wednesday. Cooler temperatures are expected
through the weekend as well.
&&
.SHORT TERM (TDY-WED)...22/932 AM.
***UPDATE***
The marine layer lowered slightly overnight and onshore flow is
about a mb weaker than yesterday so temperatures today are
expected to be warmer, in some areas as much as 5-10 degrees
warmer than yesterday. The upper low that has been very persistent
about 500 miles southwest of LAX is not expected to make any
significant moves over the next 24 hours and most of the computer
models show the low in our vicinity through next weekend, which
will make for a tricky forecast, and overall lower predictability
than usual.
The latest CAMs show just very minimal threat of convection today
and generally low chances Tuesday until at least later in the
afternoon. And even then the best chances area over the coastal
waters west of the Central Coast. Most of the models hold off the
precip til Tuesday night into Wednesday, starting with the Central
Coast then eventually spreading west into Ventura and LA County
Wednesday. The precip will be showery at best, hitting some areas
and not others. And so far most of the models are capping rates
around a quarter inch per hour, though about 5% of the GFS/ECMWF
ensembles do indicate locally higher totals and rates.
***From Previous Discussion***
On Tuesday the upper low will start to swing to the north and
will bring an area of moisture and lift to the area focused mostly
on SBA county. PWs are less than last week but will still be
significant. Values over SBA county will rise from 1 inch in the
morning to about 1.5 inches in the afternoon. PWs will decrease
both to the north and east away from SBA county. A chc of rain
will develop over SBA county in the afternoon with slight chc`s
over VTA and SLO counties. A better chc will develop Tuesday
evening and the slight chc will extend all the way to LA county.
There is enough instability with this system to include a slight
chc of TSTMs along with the showers. Rainfall amounts should not
be too impressive - a tenth or two in the afternoon and then up to
a quarter inch in the evening and overnight. Again the greatest
amounts will be over SBA county. Still with PWs near 1.50 inches
cannot rule out isolated .5 inch per hour rainfall rates under
heaviest cells. Temps on Tuesday will be very dependent on how
many clouds come over the area as well as their thickness.
The upper low pulls out towards the Bay Area on Wednesday. A
20 to 30 chc of showers/TSTMs will remain mostly in the morning
and mostly across the north sections of the counties. Rainfall
amounts and rates will be less than Tuesday`s. Max temps should
cool with an increase in onshore flow and a decrease in hgts, but
there is a chc that it will be sunnier and thus warmer.
.LONG TERM (THU-SUN)...22/221 AM.
Low confidence in the xtnd fcst. The EC and the GFS both are in
decent agreement and show the upper low wobbling around Srn CA
through at least Saturday with many solutions also showing it in
the area on Sunday. While there is some drying PWATs should remain
around .75 inches. Blended ensemble guidance does not show any
chc of rain over 12 percent, but with an upper low overhead and
some moisture the chc of afternoon mtn convection is not zero.
Have some coastal low clouds in the fcst but this is also low
confidence since the inversion may have a difficult time forming
with the upper low overhead. Also, the onshore flow is rather
weak.
With hgts not changing much and little day to day change in the
sfc gradients max temps will not change much during the period and
will remain several degrees blo normal.
&&
.AVIATION...22/1713Z.
Around 1629Z, the marine layer depth was around 1000 feet deep at
KLAX. The top of the marine inversion was near 2500 feet with a
temperature near 22 degrees Celsius.
High confidence in TAFs for KPRB, KBUR, KVNY, KPMD,
and KWJF. 10% chance for LIFR conds between 12Z and 17Z at KBUR
and KVNY.
Moderate confidence in coastal TAFs. Arrival times may be off +/-
2 hours for KSMX and KSBP, and +/- 3 hours for remaining TAFs.
There is a 15% chance for vsbys 1/2SM to 1SM at KSMO ad KLAX
between 08Z and 15Z. 10% chance of no low clouds at sites south
of Point Conception.
KLAX...Moderate confidence in TAF. Arrival may be off +/- 3 hours.
15% chance for vsbys 1/2SM to 1SM between 08Z and 15Z. Any east
wind component should remain less than 6 knots.
KBUR...High confidence in TAF. 10% chance for LIFR conds between
12Z and 17Z.
&&
.MARINE...22/820 AM.
Moderate confidence in the current forecast. There is a chance
that winds could be lighter than forecast today and this evening.
For the waters southwest through northwest of the Channel Islands
and the nearshore waters along the Central Coast, there is a
40-70 percent chance of Small Craft Advisory (SCA) level winds by
this afternoon, highest across the northern outer waters. Winds
and seas will likely drop below SCA levels between early Tuesday
morning and Wednesday morning, but local NW gusts of 20-25 knots
are possible Tuesday afternoon and evening. There is a 30-50
percent chance of SCA level winds on Wednesday afternoon and
evening, increasing to 40-60 percent on Thursday afternoon and
evening. The highest chances will be for the waters beyond 30 NM
offshore.
Inside the southern California bight, winds and seas will likely
remain below SCA levels through Wednesday afternoon, then there is
a 30-50 percent chance of SCA levels winds Wednesday and Thursday
afternoons and evenings. The highest chances will be for the
western Santa Barbara Channel.
Moisture with a tropical disturbance to the south will move
northward late Monday and bring a chance of showers to the
coastal waters from Port San Luis to the Channel Islands. Chances
for showers spread to most of the coastal waters Tuesday into at
least Wednesday, along with the addition of a chance of
thunderstorms. Low confidence exists in the exact timing and
location of showers and thunderstorms. Any thunderstorm that
forms will be capable of producing locally gale force winds and
rough seas, dangerous lightning, heavy rainfall with reduced
visibility, and waterspouts.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect until 9 PM PDT this evening
      for zones 670-673. (See LAXMWWLOX).
&&
$$
PUBLIC...MW/Rorke
AVIATION...Lewis
MARINE...Hall/Lewis
SYNOPSIS...MW
weather.gov/losangeles
Experimental Graphical Hazardous Weather Outlook at:
https://www.weather.gov/erh/ghwo?wfo=lox

NWS LOX Office Area Forecast Discussion