630
FXUS66 KLOX 311754
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
1054 AM PDT Sun Aug 31 2025

UPDATED AVIATION SECTION

.SYNOPSIS...31/357 AM.

A hot air mass will continue over the region through much of the
week as high pressure aloft will remain anchored near the Four
Corners region. Monsoonal moisture will arrive again on Tuesday
and keep a low but present risk of showers and thunderstorms
through the remainder of the week. A cooling trend is possible for
the upcoming weekend.

&&

.SHORT TERM (TDY-TUE)...31/929 AM.

***UPDATE***

The morning soundings showed a surfaced-based inversion at VBG
and a shallow marine inversion around 700 ft deep at LAX, with a
warm layer between about 3000 and 4000 ft where temps reached up
to 80 deg.

Another very warm to hot day in store for the forecast area, with
many areas away from the coast expected to top out between 95 and
105 deg this afternoon. Even the inland coastal plain should
reach into to low 90s. With the hot conditions, Heat Advisories
are in effect for most of the region, and added the northern VTU
County mtns for today and updated areas such as the I-5 Corridor
and other mtn areas to begin the Advisory today instead of
tomorrow. Most of the Heat Advisories will continue thru Tue.

Some low clouds and patchy dense fog was noted over the coastal
waters this morning, while any early morning low clouds and fog
along the coast dissipated quickly after sunrise. Some mid-level
moisture was moving into the area from the SW this morning with
scattered altocu, otherwise mostly sunny skies prevailed which
will continue thru the afternoon.

***From Previous Discussion***

The latest water vapor imagery shows an upper-level ridge of high
pressure centered over south Texas this morning. This ridge will
expand and build into Four Corners Region today and remain in
place through much of the week. A warming trend will continue
through Tuesday as 500 mb heights climb a bit each day. Heat risk
values are starting to tick a little higher and are marginal
enough to extend heat advisories across the Southland to start
later this morning rather than Monday morning.

To the north, heat advisories will go into effect later this
morning as weak offshore flow develops. Breezy Santa Lucia winds
are already in place this morning with gusts between 25 and 30 mph
being recorded this morning. Temperatures will warm to near
dangerous levels today. Some foothills and mountain stations
indicate overnight low temperatures only falling into the mid to
upper 70s and lower 80s, so far.

While some heat advisory headlines extend into Tuesday, there is
a chance that monsoonal moisture could slip in on Tuesday. The
latest deterministic solutions agree well with GEFS ensemble
members to bring a cloudier pattern across the region on Tuesday
with showers chances entering the forecast. This could end up
cutting into temperatures and bring the threat of showers and
isolated thunderstorms to most areas south of Point Conception.
Much will depend how much cloud coverage develops and how much
moisture spills into the region on Tuesday.

.LONG TERM (WED-SAT)...31/354 AM.

High pressure aloft, albeit weaker, will linger over the
southwestern United States into Wednesday and Thursday. A very
warm air mass with added humidity from the Desert Monsoon is
likely to persist. Temperatures above seasonal normals should be
expected into at least Thursday. There is a moderate chance that
heat headlines may be extended into Wednesday or Thursday. With
the increased monsoon moisture and overall hot air mass in place,
Tuesday night may end up being the warmest night of the week,
giving daytime heating a head start for Wednesday. Overnight low
temperatures across much of the LA metro area could remain above
70 degrees, while many foothill and mountain areas may see
overnight low temperatures in the mid 70s to lower 80s, adding to
the heat risk.

A cooling trend should develop on Friday and into next weekend.
The latest ensemble members shows 500 mb height means trending
downward through much of next weekend.

Southeast flow aloft will likely be in place between Tuesday and
Friday. The area will sit on the western edge of the monsoon, and
there will likely be shower and thunderstorms chances in the
forecast each day. The highest chances of showers and
thunderstorms will likely persist across the San Gabriel
Mountains and Antelope Valley, but there is a chance that an
easterly wave could push underneath the ridge into southern
California. Chances for showers and thunderstorms cannot be ruled
out entirely during the long term period.

&&

.AVIATION...31/1753Z.

Around 1722Z at KLAX, the marine layer was 400 ft deep. The top
of the inversion was at 2400 ft with a temperature of 27 C.

Low confidence in TAFs for KSBA, KOXR, KCMA, KSMO, KLAX, and KLGB
due to uncertainty of low clouds. There is a chance for no low
clouds at KSBA (40%), KOXR (20%), KCMA (30%), KSMO (40%), KLAX
(40%), and KLGB (40%). Otherwise, timing of flight cat changes
may be off +/- 3 hours and minimum cig heights may be off +/- 300
feet. There is a 10-30% chance for vsbys less than 1SM, highest
chances at KOXR and KCMA.

High confidence in remaining TAFs. There is a 15% chance for
VLIFR/LIFR conds between 10Z and 17Z at KSMX and KSBP.

KLAX...High confidence in TAF through 03Z, then low confidence
thereafter. There is a 40% chance for no low clouds. If they do
arrive, there is a 25% chance for cigs OVC002-004 and 15% chance vsbys
1/2SM-1SM. Timing of arrival of low clouds may be off +/- 3 hours.
High confidence that any east wind component will remain below 7
kt.

KBUR...High confidence in TAF.

&&

.MARINE...31/812 AM.

High confidence in 20-30 kt NW winds across the Outer Waters from
Point Sal north to Point Piedras Blancas continuing through Labor
Day (Monday). Moderate confidence in the remaining Outer Waters
remaining below Small Craft Advisory (SCA) criteria through Monday
morning, then a 30% chance of winds increasing to SCA levels
during the afternoon and evening hours Monday. Tuesday into
Thursday, the best chances for SCA winds are focused around Point
Conception south to San Nicolas Island, but winds may reach SCA
thresholds everywhere. A relative lull in winds will be likely
each morning.

Moderate confidence in forecast for the nearshore waters along
the central coast. Winds and seas will remain relatively light and
small into Tuesday, but winds look to increase Wednesday and
Thursday afternoon and evening.

Aside from fairly seasonal afternoon and evening localized NW
wind gusts 20-25 kts in the far Western Portion of the Santa
Barbara Channel and 15-20 kts in the San Pedro Channel, light
winds and small seas will be common for the nearshore waters south
of Point Conception through Labor Day. Better chances for more
widespread SCA winds on Tuesday through Thursday during the
afternoon and evenings.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory remains in effect until 6 PM PDT Tuesday for
      zones 38-88-344-345-353-356>358-368>376-378-379-548. (See LAXNPWLOX).
     Beach Hazards Statement in effect through Monday evening for
      zones 340-346-354-362-366. (See LAXCFWLOX).
     Heat Advisory remains in effect until 6 PM PDT this evening
      for zones 341>343-347>349-351-355. (See LAXNPWLOX).
     Heat Advisory remains in effect until 10 AM PDT Monday for
      zone 352. (See LAXNPWLOX).
     Heat Advisory in effect until 6 PM PDT Tuesday for zone 377. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT Tuesday for
      zone 670. (See LAXMWWLOX).

&&

$$

PUBLIC...Hall/Sirard
AVIATION...Lewis
MARINE...Lund/Lewis
SYNOPSIS...Hall

weather.gov/losangeles

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