344
FXUS66 KLOX 032356
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
456 PM PDT Wed Sep 3 2025

UPDATED AVIATION SECTION

.SYNOPSIS...03/130 PM.

Heat relief is coming. Temperatures will slowly lower through
Friday, including the abnormally warm overnight temperatures.
Monsoonal moisture will remain over the region through Thursday,
but the risks for significant impacts have lowered. Slight warming
on track Saturday through Monday, then a likely big cool down to
follow.

&&

.SHORT TERM (TDY-SAT)...03/157 PM.

Clouds are bubbling up over the mountains from Santa Barbara
County to Los Angeles County, but they look rather flat. With all
of the current activity matching the modeling well, and not a
single model projecting any thunderstorms or rain over our area,
will be dropping the Flood Watch early. Still keeping the 10 to 20
percent chance of thunderstorms for each afternoon through
tomorrow over the Los Angeles and Ventura County Mountains as the
convective parameters are still there, but the chance for
everything to line up for flash flooding is extremely low. The
latest consensus of tracks for the remnants of Tropical Storm
Lorena continues to push it further to the east of our area. This
is still something to monitor, but still looks like to be any part
of our story. As a result, precipitable water values should fall
below one inch by Friday, and the thunderstorm threat is below
mentionable by then. Not seeing any appreciable monsoonal surge
chances through at least the middle of next week.

The high pressure center that brought all the heat stretching back
to last week will continue to weaken through Friday or Saturday.
Onshore flow and pressure gradients will also trend more and more
onshore each day through Saturday. This will all lead to a steady
lowering of daytime temperatures. More significantly, with the
monsoonal moisture steadily declining each day, night time
temperatures and overall mugginess will noticeably improve each
day. As such, the current Heat Advisories will be allowed to
expire on time at 6pm this evening with no changes or extensions
planned.

Other than that, we are looking at a pretty benign rest of the
week. The flow aloft will turn from moist southeast today to dry
southwest by Saturday. Some gusty Sundowner winds will form each
evening, as well as some gusty onshore winds over the interior,
but nothing looks to approach Advisory levels.

.LONG TERM (SUN-WED)...03/220 PM.

High pressure aloft will peak on Sunday or Monday (around 590
decameters) with onshore pressure gradients weakening to around +1
millibars. This should allow temperatures to push back up to a few
degrees above normal. Thankfully overnight temperatures will
change little due to the dry airmass (nothing like the very warm
nights we have been having). The risk for Heat Advisories is
close to zero.

More and more of the ensemble projections (on the order of 70%)
are now on board for a large trough of low pressure quickly
dropping over the west coast on Tuesday then moving very slowly
for the rest of next week. This surely means an extended period of
temperatures much below normal from Tuesday onward and a likely
deep and expansive marine layer. Some solutions have the core of
the low cutting off and drifting right over southern California on
Friday. Such a solution could bring a few showers but we have some
time to figure that out.

&&

.AVIATION...03/2351Z.

Due to a national METAR outage, there will be limited or no
amendments until observations are restored.

At 2305Z at KLAX, the marine layer was 500 ft deep. The top of
the inversion was at 2400 ft with a temperature of 27 C.

High confidence in VFR TAFs for KPRB, KBUR, KVNY, KPMD, and KWJF.

Low confidence in arrival of low clouds for KOXR and KCMA. There
is a 40% chance for no low clouds tonight. If low clouds arrive,
40% chance for LIFR conds.

Moderate confidence in remaining TAFs. Good confidence in low
clouds arriving at KSBP and KSMX tonight after 02Z, but arrival
and dissipation may be off +/- 90 minutes. There is a 30% chance
for vsbys less than 1SM. At KSBP, there is a 20% chance for no low
clouds tonight. There is a 15% chance for LIFR to IFR conds at
KSMO, KLAX, and KLGB between 10Z and 17Z.

KLAX...Moderate confidence in TAF. There is a 15% chance of LIFR
to IFR conditions 10Z to 17Z Thursday. No significant east wind
component expected.

KBUR...High confidence in VFR TAF.

&&

.MARINE...03/134 PM.

Moderate to High confidence in current forecast.

For the Outer Waters, Small Craft Advisory (SCA) winds will be
present especially during the afternoon/eve hours across PZZ670,
south of Point Conception, & around the Channel Islands through
the weekend. Relative lulls are expected during the morning hours.
Seas will peak around 7 feet Thursday into Friday, becoming small
over the weekend.

For the Inner Waters along the Central Coast, moderate chances
each day during the afternoon & evening timeframe for SCA level
wind gusts especially across NW portions of PZZ645 and nearshore
Port San Luis through the weekend.

Inside the southern California bight, there is a moderate to high
chance of SCA level winds each afternoon/eve through Thursday
evening - especially across western/southern portions of the Santa
Barbara Channel, near Point dume, & into the San Pedro Channel.
Over the weekend, moderate chances for SCA level winds across the
western portion of the SBA Channel in the afternoon & evening.
Seas will remain small.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory remains in effect until 6 PM PDT this evening
      for zones 88-355>358-368>375-548. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 9 PM PDT this evening
      for zones 645-650-670. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Thursday for
      zones 673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Kittell
AVIATION...Lewis
MARINE...Black
SYNOPSIS...RK

weather.gov/losangeles

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

NWS Flagstaff Office