780
FXUS66 KLOX 210941
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
241 AM PDT Mon Sep 21 2026

.SYNOPSIS...21/240 AM.

A weak upper level trough will move over the area today, cooling
temperatures and increasing marine layer stratus. A warming trend
will begin Tuesday and peak on Wednesday, with highs 5 to 10
degrees above normal.

&&

.SHORT TERM (TDY-WED)...21/240 AM.

A high hgt (576 dam) will move over Srn Ca today. The lift from
this low will deepen the marine to about 4000 ft and marine layer
stratus will cover all of the csts and vlys. Some drizzle is
possible this morning esp near the foothills. Look for slow
clearing and a good chance of reverse clearing where the csts
clear faster than the vlys. The deep marine layer, falling hgts
and stubborn widespread clouds will bring 4 to 8 degrees of
cooling to all areas. Highs today across the csts and vlys will
mostly be in the 70s with a smattering of lower 80s. Most max
temps will end up around 8 degrees under normal.

A small ridge will move into the area Tuesday and Wednesday. Hgts
will rise to about 582 dam. More importantly there will be good
offshore trends both days. This will lead to only weak onshore
flow to the east and actual offshore flow from the north in the
mornings. Look for a reduction in the marine layer cloud coverage
as well as much earlier and complete clearing. Max temps will
rise 2 to 4 locally 6 degrees on Tuesday. Due the weakened onshore
flow, Wednesday will see a big 8 to 12 degree jump in temps.

Wednesday`s temps should mostly end up in the 80s across the csts
and in the 90s in the vlys. These max temps are 3 to 6 degrees
above normal except for the Central Coast where there will be
about 10 degrees over normal. There is a 20 to 25 percent chc that
the forecast is not warm enough and max temps will end up high
enough to warrant some heat advisories.

.LONG TERM (THU-SUN)...21/241 AM.

Broad troffing will likely cover the state later this week and
into the weekend. The GFS does favor a ridge on Sunday but the EC,
the EC-AI and many ensembles show the trof hanging on to the
coast.

The onshore gradients will be fairly week through the period and
there will be some weak offshore flow from the north during the
mornings. This and the fact the troffing is not very sharp or
dynamic will likely result in only a patchy marine layer stratus
pattern.

Max temps will cool a little on most of the days, but most temps
will remain a few degrees above normal. Blended ensemble guidance
shows 4 to 8 degrees of cooling on Sunday, but this may be over
done given the 586 fcst hgts and offshore flow from the north in
the morning.

&&

.AVIATION...21/0940Z.

At 0832Z at KLAX, the marine layer was 1900 ft deep. The top of
the inversion was at 4900 ft with a temperature of 19 C.

High confidence in VFR conds for KPMD & KWJF.

Low to moderate confidence in the remaining sites. The timing of
CIG and any VSBY restrictions may be off 2 hrs and flight minimums
by one category. Cigs may bounce between categories. There is a
10 percent chance of -DZ through 18Z.

KLAX...Moderate confidence in TAF. Cigs may vary between 015 and
030 through 18Z. There is a 30 percent chc of no clearing. Any
east wind component is expected remain less than 6kt.

KBUR...Moderate confidence in TAF. There is a 30 percent chc of
BKN015 conds through 14Z.

&&

.MARINE...21/241 AM.

For the outer waters, moderate confidence in the current
forecast. Small Craft Advisory (SCA) level winds are likely
(60-80 percent chance) for the waters around Point Conception
through late tonight. There is a 40-50% chance of SCA wind gusts
west and south of Point Conception Tuesday afternoon and night as
well, otherwise conds will be below SCA levels through Thursday
night. Expect steep, choppy seas with the SCA conditions.

For the inner waters N of Point Sal, moderate confidence in the
current forecast. SCA wind gusts are possible (30-40 percent
chance) during the afternoon and evening today and again Tuesday.
Conds are otherwise expected to be below SCA levels through
Thursday.

For the inner waters S of Point Conception, moderate to high
confidence in the current forecast. Conds are expected to be below
SCA levels for the most part through Thursday night. However, for
the western Santa Barbara Channel, there is a 30-40% chance
this afternoon/evening and Tuesday afternoon/evening.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect until 3 AM PDT early this
      morning for zone 670. (See LAXMWWLOX).
     Small Craft Advisory in effect until 5 AM PDT Tuesday for
      zone 673. (See LAXMWWLOX).

&&

$$

PUBLIC...Rorke
AVIATION...Rorke
MARINE...Ciliberti/RS/RM
SYNOPSIS...MW/Sirard

weather.gov/losangeles

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