Duarte Weather

632
FXUS66 KLOX 240928
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
228 AM PDT Mon Aug 24 2026

.SYNOPSIS...24/158 AM.

Very hot conditions will dominate the week, with a high risk for
heat illness. Patchy night through morning low clouds and locally
dense fog will be confined to coastal areas, mainly north of
Point Conception.

&&

.SHORT TERM (TDY-WED)...24/158 AM.

The story this entire week will be the heat.

A 597 dam upper high will sit, quasi-stationary, over NM
through the period. Hgts over Srn CA will be around 593 dam all
three days. At the sfc the E/W gradient will oscillate between
near very weak onshore flow in the morning to mdt onshore flow in
the afternoon. In the N/S direction there will be weak onshore
flow each afternoon, but in the mornings there will be increasing
offshore flow.

The strong high pressure aloft, weak offshore flow from the north
and lack of an eddy will limit the amount of low clouds south of
Pt Conception each morning. The Central Coast will have more low
clouds but since the marine layer will be squashed to under 800 ft
there will be areas of dense fog each morning.

There will not be too much in the way of winds given the lack of
strong sfc gradients. The only exception will be the SBA south
coast where there will be Sundowners each night. There is a chc
that the gusts will reach advisory levels Tuesday night.

But still, everything is about the heat. Today may be a few
degrees cooler than it was ydy as the upper high wobbles slightly
to the east. Max temps will still end up 6 to 12 degrees above
normal. Vly temps will rise to 96 to 106 degrees. Heat advisories
are in effect for the vlys, lower mtn elevations and far interior.

The offshore flow from the north increases on Tuesday as does the
offshore flow across the Central Coast. This will bring 1 to 3
degrees of warming to most areas, except for the Central Coast
which will see a 8 to 12 degrees of warming. Vly Temps will end up
between 100 and 110 degrees. Inland coastal areas such as DTLA,
LGB and SLO will have max temps in the 90s. Heat advisories may be
needed for these inland coastal areas.

Another increase in the offshore flow from the north and across
the Central Coast will add another 1 to 3 degrees of warming to
most of the area. Triple digit heat will cover almost the entire
forecast areas save for the beaches which will still have highs in
the 80s and the Central Coast which will see max temps in the
upper 80s and 90s. Of note: The EC is still forecasting offshore
flow from both the east and north and if this were to happen max
temps would be even higher in the vlys and significantly higher
across the csts. This scenario seems less likely now, however, as
the NAM does show continued onshore flow to the east. It is almost
a certainty that all of the heat watches will be converted to
warnings and much of the rest of the area will be covered with
heat advisories.

One last heat reflated issue, due to the very warm atmosphere and
powerful inversion under the upper high, overnight low temps will
also be 6 to 12 degrees over normals with some vly areas
experiencing 80s for the bulk of the night. These low temps will
add to the heat risk as people who lack air conditioning will not
be able to cool off overnight.

.LONG TERM (THU-SUN)...24/158 AM.

Not much change in the upper levels on Thursday and Friday. The
sfc gradient problem in the E/W direction remains with the EC
remaining significantly offshore while the GFS keeps it onshore.
Given how the NAM is tracking the gradients it seems the best bet
is for onshore gradients, but weaker than the GFS is forecasting.
All mdls show offshore flow from the north, but again the EC is
much stronger.

Thursdays temps will be very similar to Thursday`s with most max
temps 10 to 15 degrees above normal. High confidence that all of
the heat warnings and advisories will continue.

The current forecast for Friday shows some cooling. This is a low
confidence forecast and depends on the gradient forecast. There is
a very good chc that temps will be very similar to Thursday`s
values.

The overnight lows will continue 8 to 12 degrees above normal and
this will greatly exacerbate the heat risk as there will be no
time for people`s body to release the heat stress.

Very hot sundowners across southern SBA county remain a concern
as well. A decent N to S gradient will set up over the county each
evening and gusty north canyon winds will develop. These hot
winds could drive max temps into the 100-105 degree range and
could also keep temperatures in the 80s until almost dawn.

Better confidence in a noticeable cooling trend for the weekend.
Both the EC and GFS agree that troffing will move into the west
coast and force the upper high to the east. Hgts will fall to 590
dam Sat and then to 588 dam on Sun. More importantly both mdls
show a return to onshore flow from both the South and West. Look
for 2 to 4 degrees of cooling on Saturday and an additional 3 to 6
degrees on Sunday. Even with the cooling, Sunday`s max temps will
end up 2 to 4 degrees above normal south of Pt Conception. The
Central Coast will fall a few degrees blo normal.

&&

.AVIATION...24/0917Z.

At 0822Z at KLAX, the marine layer was 500 feet deep. The top of
the inversion was at 2500 feet with a temperature of 30 C.

High confidence in TAFs for KPRB, KSBA, KOXR, KCMA, KSMO, KWJF
and KPMD.

For KSBP and KSMX, timing of flight category changes could be +/-
2 hours of current forecast.

For KLGB, there is a 10-15% chance of LIFR/IFR conditions
12Z-16Z.

KLAX...Low confidence in TAF with a near 50 percent chc of no low
clouds. No significant easterly wind component is expected.

KBUR...High confidence in CAVU TAF.

&&

.MARINE...24/158 AM.

For the Outer Waters, high confidence in current forecast. Today
through Friday, Small Craft Advisory (SCA) winds are expected to
continue although the winds will drop briefly across PZZ670
tonight and Monday. Short period SCA level seas (5 to 7 feet at
6-8 seconds) will continue along with the gusty winds. Wednesday
into Thursday, larger seas approaching 7-9 feet are likely.

For the Inner Waters north of Point Sal, moderate to high confidence
in current forecast. Today through Monday night, high confidence
in winds and seas remaining below SCA levels. For Tuesday through
Friday, there is a 50-70% chance of SCA level winds each afternoon
and evening.

For the Inner Waters south of Point Conception, moderate to high
confidence in current forecast. For a majority of the southern
Inner Waters, high confidence in winds and seas remaining below
SCA levels through Friday. The only exception will be the western
half of the Santa Barbara Channel where there is a 60-80% chance
of SCA level winds Monday through Friday, mainly in the late
afternoon and evening hours.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory in effect until 10 AM PDT Tuesday for zones
      38-87-88-349>358-362-366>376-378>380-548. (See LAXNPWLOX).
     Extreme Heat Watch in effect from Tuesday morning through
      Friday evening for zones
      38-87-88-349>358-362-366>376-378>383-548. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 4 AM PDT Tuesday for
      zones 673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Rorke
AVIATION...Rorke
MARINE...RAT/Ciliberti
SYNOPSIS...RK

weather.gov/losangeles

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

NWS LOX Office Area Forecast Discussion