837
FXUS66 KLOX 180955
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
255 AM PDT Tue Aug 18 2026

.SYNOPSIS...18/254 AM.

Night through morning marine layer clouds will be confined to the
coastal areas, mostly north of Pt Conception, through much of
this week. Warmer and drier conditions are expected away from the
immediate coast, with peak heat likely being Tuesday through
Thursday when moderate heat risk is expected in warmest locations.

&&

.SHORT TERM (TDY-THU)...18/255 AM.

Very little change to the forecast thinking for the next 7 days.
A large and very warm upper high stretching from TX to Srn CA will
remain in place through the period. Hgts will be around 594 to
595 dam. SFC gradients will also be fairly static. The W/E
gradient will be weakly onshore during the mornings and moderately
onshore during the afternoons, while the N/S gradient will be
near neutral in the mornings becoming weakly onshore in the
afternoons.

There will not be much of an eddy to generate low clouds south of
Pt Conception so there will only be patchy morning low clouds at
most across the VTA/LA csts as well as the SBA south coast. The
Central Coast will see a fairly robust marine layer cloudy pattern
each morning as the onshore flow up there will be stronger.

Higher than normal hgts, weaker than normal onshore flow and sunny
skies will all combine to bring 2 to 4 degrees of warming today, 1
to 3 degrees on Wednesday and another 1 to 2 degrees on Thursday
for areas south of Pt Conception (The Central Coast will cool some
as the sea breeze increases). Max temps in the vlys, lower mtn
elevations and far interior will range from 95 to 105 degrees or 4
to 8 degrees over normal. The strong inversion, much warmer than
normal sea surface temps and the warm atmosphere will also bring
above normal overnight low temps to much of the area. Most
coast/valley locations will only have lows in the upper 60s to
lower 70s.

The combination of warmer than normal highs and lows will bring
Moderate HeatRisk to many areas. Heat advisories start later this
morning and continue through Thursday for the San Fernando, San
Gabriel, and Santa Clarita Valleys as well as the lower mtn
elevations. The VTA county valleys, and the Santa Monica mtns will
also need heat advisories starting Wednesday. Additionally, there
is a small chance that heat advisories will need to be extended
into Friday. Please see the product LAXNPWLOX for all of the
details.

Gusty north winds will affect southwest Santa Barbara County and
the I-5 corridor near the Grapevine each evening and overnight.
The gusts should almost all be below advisory levels with only a
chc of isolated advisory level (45 mph) gusts in the Gaviota area.

.LONG TERM (FRI-MON)...18/159 AM.

All medium range mdls agree that the upper high will shift to the
four corners area by Friday, which will set up SE monsoon flow
over Southern CA. This SE flow will allow precipitable Water
values to approach 1.5" across southern L.A. County starting
Friday afternoon. This influx of moisture will allow for a 5-10
percent chance of showers or thunderstorms to to develop over the
LA County mountains and Antelope Valley Friday afternoon through
the weekend. Hgts fall a to 592 dam and there will be an increase
in mid and high level clouds as well. These two things will likely
bring 1 to 3 degrees of cooling. Future shifts will have to weigh
the opposing effects of the cooler temps vs the increased
humidities and consider extending the heat advisories for one more
day. Right now this appears to be about a 30 percent chc.

The upper high will shift slowly eastward Saturday through Monday
and hgts will fall to about 590 dam. The onshore gradients do not
change much so the pattern of plenty of morning low clouds over
the Central Coast and minimal low clouds for areas south of Pt
Conception should continue. 1 to 2 degrees of cooling each day
should bring most max temps down to a few degrees under normal by
Monday.

&&

.AVIATION...18/0955Z.

At 0822Z at KLAX, the marine layer was 600 feet deep. The top of
the inversion was 2300 feet with a temperature of 28 C.

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

Fair confidence in TAFs for KSBP and KSMX. VFR conds could arrive
+/- 1 hour from fcst time. There is a 25 percent chc of 1/4-1/2SM
vsbys 11Z-15Z.

Moderate confidence in the remainder of TAFs with a 30 percent
chc of IFR cigs at any given site 13Z-17Z.

KLAX...Moderate confidence in TAF. There is a 30 percent chance
of BKN008 conds 13Z-17Z. No significant easterly wind component
is expected.

KBUR...High confidence in CAVOK TAF.

&&

.MARINE...18/253 AM.

For the Outer Waters, high confidence in current forecast. Small
Craft Advisory (SCA) level winds are expected through Saturday.
Building short- period seas will also affect the Outer Waters,
rising to the 6-9 foot range.

For the Inner Waters north of Point Sal, moderate confidence in
current forecast. Through Wednesday, there is a 30-40% chance of
SCA level winds in the afternoon and evening hours. For Thursday
through Saturday, there is a 50-70% chance of SCA level winds in
the afternoon and evening hours.

For the Inner Waters south of Point Conception, moderate to high
confidence in current forecast. For the western half of the Santa
Barbara Channel, there is a 60% chance of SCA level winds late
this afternoon and tonight. Then there is a 30-40% chance of SCA
level winds during the afternoon to evening hours Wednesday
through Saturday. Elsewhere south of Point Conception, high
confidence in winds and seas remaining below SCA levels through
Saturday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory in effect from 10 AM this morning to 8 PM PDT
      Thursday for zones
      38-88-343>345-351-353-371>373-375-376-379-380-548. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT Wednesday for
      zones 670-673-676. (See LAXMWWLOX).

&&

$$

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

weather.gov/losangeles

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