939
FXUS66 KLOX 031445
AFDLOX

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

.SYNOPSIS...03/259 AM.

Very warm conditions will continue through this evening, then
temperatures will lower some through the end of the week.
Monsoonal moisture will remain over the region through Thursday,
bringing risks of strong winds, brief heavy downpours, lightning,
and fire starts over Los Angeles County.

&&

.SHORT TERM (TDY-FRI)...03/259 AM.

Quite weather covers Srn CA at the moment. Skies are clear and
temps are above normal and its a little on the humid side. There
is hardly any upper flow over the area as the upper high that was
over UT ydy has weakened considerably. There is little to no
marine layer clouds this morning and also very little in the way
of mid and high level debris clouds. The extra sunshine and lack
of marine layer will bring 1 to 3 degrees of warming to most
areas. This warming along with the continued higher than normal
humidity will bring advisory level heat to most areas away from
the beaches. There is still enough moisture left in the atmosphere
(1.25" PWATs) to bring a chance of afternoon TSTMs over the VTA/LA
mtns as well as the Antelope Vly. Any TSTM that forms will move
very slowly due to the very weak steering flow and this will
enhance the potential for flash flooding. A Flash Flood Watch is
in effect for the VTA/LA mtns as well as the Antelope Vly

Things begin to settle down on Thursday. Weak flow will remain
aloft as the area will sit under the eastern edge of an E Pac
high. Hgts will fall to 588 dam about 3 dam lower than today.
There will also be a significant increase in onshore flow both to
the east and north. despite the increase in onshore flow, there
will likely not be much of any marine layer stratus in the morning
as there is just no source of lift. Most max temps will cool 3 to
5 degrees and while max temps will end up several degrees over
normal it will not be advisory level heat. It will also be less
humid making things feel even better. Just enough moisture at the
higher levels to bring a slight (20 percent) chc of TSTMs to the
mtns in the afternoon.

Hgt fall further to 585 dam on Fri. Onshore flow will continue to
increase. Low cloud will likely form across many of the coasts.
The flow will be from the west and will be dry eliminating the
TSTM threat. Most areas will cool an additional 2 to 4 degrees.
Max temps away from the beaches in the cstl areas will be in the
upper 70s to mid 80s, while the vlys will mostly end up in the
upper 80s to mid 90s.

.LONG TERM (SAT-TUE)...03/307 AM.

Benign weather on tap for the four day xtnd period. Broad troffing
will move into the western states over the weekend and then the
trof will sharpen early next week. There will be onshore flow
through the period with a moderate onshore push to the east in the
afternoons. The marine layer clouds will likely cover most of the
coasts and may xtnd into the lower vlys. But other than the
morning stratus skies should be mostly clear.

Max temps will fall another 1 to 3 degrees over most of the area
(The Central Coast will warm some as there will be weaker onshore
flow there). This cooling will bring most max temps down to 2 to 4
degrees blo normal. After Saturday`s cooling there will be little
day to day change in temps.

&&

.AVIATION...03/1109Z.

Around 09Z, the marine layer depth was around 500 feet deep at
KLAX. The top of the inversion was near 2000 feet with a
temperature around 28 degrees Celsius.

A national METAR outage continues across the region, and there
will be limited or no amendments until observations are restored.

Moderate confidence in the current forecast for coastal terminals.
Higher confidence in the current forecast for valley and desert
terminals. There is a moderate to high chance of LIFR to IFR
conditions through 16Z, and again after 08Z Thursday for coastal
terminals. There is a low chance of thunderstorms at Los Angeles
County terminals, highest for the desert terminals.

KLAX...There is a 30 percent chance of LIFR to IFR conditions
through 16Z, and after 08Z Thursday. There is a 10 percent chance
of a thunderstorms between 20Z and 02Z. Any east winds will remain
less than 7 knots.

KBUR...There is a 10 percent chance of a thunderstorms between
20Z and 02Z. No wind impacts are expected at this time.

&&

.MARINE...03/744 AM.

Moderate confidence in the current forecast. Higher confidence in
the forecast for seas relative to winds.

For the waters southwest through northwest of the Channel Islands
and the nearshore waters along the Central Coast, there is a
high-to-likely chance of Small Craft Advisory (SCA) northwest
winds through at least Thursday evening. The highest chance will
be for the waters from around Point Conception south to San
Nicolas Island with elevated chance offshore of the Monterey-San
Luis Obispo County border. There is a moderate-to-high chance of
SCA level winds each afternoon and evening over the weekend,
increasing to a high chance for early next week.

Inside the southern California bight, there is a moderate-to-high
chance of SCA level winds each afternoon and evening through
Thursday evening, highest across the western/southern portion of
the Santa Barbara Channel and into the Anacapa Passage, near Point
Dume, and into the San Pedro Channel. Winds and seas should drop
below SCA levels over the weekend, but start to increase again
early next week.

&&

.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).
     Flood Watch in effect through this evening for zones 379>383. (See LAXFFALOX).
PZ...Small Craft Advisory in effect from 3 PM this afternoon to 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...Rorke
AVIATION...Hall
MARINE...Hall/Black
SYNOPSIS...RK/CC

weather.gov/losangeles

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