Naples, California Weather Forecast Discussion

495
FXUS66 KLOX 210245
AFDLOX
Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
745 PM PDT Sat Sep 20 2025
.SYNOPSIS...20/352 PM.
Monsoonal moisture will begin to move north again on Sunday, and
a return of showers and thunderstorms will be possible as early
as Sunday afternoon and evening over the mountains. Any shower
activity for the coastal and valley areas will likely hold off
until Tuesday.
&&
.SHORT TERM (SAT-TUE)...20/745 PM.
***UPDATE***
Latest satellite and surface observations indicate stratus/fog
beginning to develop across the coastal plain with clear skies
elsewhere. Current sounding data indicates marine inversion
hovering around 900 feet in depth.
For the immediate short term, only issue will be the behavior of
the marine layer stratus. Overnight, models indicate lowering H5
heights as upper low establishes itself offshore. So, the
inversion should deepen a bit overnight and stratus should push a
bit further inland, but still mainly affect the coastal plain.
There will be some patchy dense fog this evening, but it should
gradually dissipate as the inversion deepens. So, do not plan on
any Dense Fog Advisories at this time (but this possibility will
need to be monitored by the night shift). Otherwise, no issues
with any other sensible weather parameters are expected overnight.
Current forecast has good handle on the immediate short term. So,
no significant updates are expected.
***From Previous Discussion***
The respite between monsoonal surges continues today with just
some light cumulus over the mountains and lingering stratus along
portions the coast. For the most part this pattern will continue
at least another day. Forecast soundings do indicate a slight
uptick in instability across the mountains Sunday afternoon so
there is a 15-20% chance of a storm developing there. Otherwise
Sunday will feel a lot like Saturday with temperatures within a
few degrees of normal for this time of year.
The forecast predictability starts dropping off Monday into
Tuesday as another semi-cutoff upper low moves into position about
500 miles southwest of LAX and begins to pull up moisture from
the next tropical wave off Mexico. This wave is not as strong as
the last one and by most accounts PW`s are expected to peak about
a half inch less than the last one. However, there is still enough
instability and moisture for scattered showers and thunderstorms.
The most likely period would be Monday night into Tuesday. Highs
Monday could potentially warm up several degrees if the latest NAM
showing a 2mb offshore trend is correct. However, most of the
guidance suggests little change Monday and the official forecast
reflects little change as well.
With the increasing humidities and likely more cloud coverage and
possible showers temperatures Tuesday in most areas should be
cooler, possibly much cooler. However, if the clouds and moisture
don`t pan out the forecast is likely too cool.
.LONG TERM (WED-SAT)...20/216 PM.
Models are mixed on how long it will take for this next upper
low, which is creating the conduit for northward moving monsoonal
moisture, to move east. To account for the slower moving solutions
shower chances are in the Wednesday forecast as well, but more
than likely any additional precipitation Wednesday will be
confined to the mountains. With that in mind, temperatures
Wednesday should recover back to normal levels with increased
sunshine.
The rest of next week looks benign with temperatures near normal.
Will likely get a return of marine layer stratus as the air mass
stabilizes but that could take a few days. Most of the models are
showing high pressure aloft building back in next Thu/Fri for
slightly warmer temperatures and less humid conditions.
&&
.AVIATION...20/2243Z.
At 2200Z at KLAX, the marine layer was 900 ft deep. The top of
the inversion was at 2900 feet with a temperature of 22 degrees
Celsius.
For the 00Z TAF package, high confidence in valley/desert TAFs,
but moderate confidence in coastal TAFs. For coastal TAFs, high
confidence in return of CIG/VSBY restrictions, but low to moderate
confidence in timing of flight category changes.
KLAX...Moderate confidence in 00Z TAF. Timing of flight category
changes could be +/- 3 hours of current forecasts. No significant
easterly wind component is expected.
KBUR...High confidence in 00Z TAF. There is a 10-15% chance of
IFR/LIFR conditions 08Z-16Z.
&&
.MARINE...20/734 PM.
For the Outer Waters, moderate to high confidence in current
forecast. Small Craft Advisory (SCA) wind gusts are expected (60%
chance) from late today into Sunday afternoon for the waters S
and W of the Channel Islands. Another round of SCA level wind
gusts will be possible at times (50% chance) Tuesday afternoon and
evening for the southern waters. Otherwise, conds are expected to
remain below SCA levels through Thursday night.
For the Inner Waters north of Point Sal, moderate to high
confidence in current forecast. Conds are largely expected to be
below SCA levels through Thursday night, However, there is a
20%-30% chance of SCA level wind gusts at times on Sunday and
again Tuesday afternoon and evening.
For the Inner Waters south of Point Conception, moderate confidence
in current forecast. SCA level winds have ended this evening
evening across the western/southern portions of the Santa Barbara
Channel. There is a 40-50% chance of SCA conds again each
afternoon and evening Tuesday through Thursday night. Otherwise,
winds and seas should generally remain below SCA levels through
Thursday night.
A closed upper level low will draw tropical moisture from the
south over the coastal waters early next week. Rain chances could
begin over far southern portions of PZZ655/676 Sunday afternoon,
but as of now coverage looks to be limited. For Monday & Tuesday,
widespread showers with the potential for thunderstorms may affect the
coastal  waters, with the highest impacts likely south of Point
Conception.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect until 3 PM PDT Sunday for zone
      673. (See LAXMWWLOX).
     Small Craft Advisory in effect until 9 AM PDT Sunday for zone
      676. (See LAXMWWLOX).
&&
$$
PUBLIC...MW/Thompson
AVIATION...RAT
MARINE...Sirard/Ciliberti
SYNOPSIS...MW/Hall
weather.gov/losangeles
Experimental Graphical Hazardous Weather Outlook at:
https://www.weather.gov/erh/ghwo?wfo=lox

NWS LOX Office Area Forecast Discussion