803
FXUS66 KLOX 080307
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
807 PM PDT Mon Sep 7 2026

.SYNOPSIS...07/601 PM.

A significant southerly swell will cause hazardous surf
conditions at the beaches through at least Tuesday. Isolated
showers will continue at times through Tuesday. The combination of
increasing heat and humidity across the area will cause moderate
to major impacts, focused over the coasts and valleys Tuesday
through at least Thursday.

&&

.SHORT TERM (MON-THU)...07/806 PM.

***UPDATE***

Here are the top ten rainfall totals for this event:

PRELIMINARY PRECIPITATION TOTALS

.TOP RAINFALL AMOUNTS FROM ALL LOCAL AREAS
OPIDS CAMP (LA COUNTY)....................... 1.86
STUNT RANCH (LA COUNTY)...................... 1.58
CHILAO SOUTH (LA COUNTY)..................... 1.57
BEL AIR (LA COUNTY).......................... 1.56
CHILAO (LA COUNTY)........................... 1.56
MONTE NIDO (LA COUNTY)....................... 1.53
BURBANK (KBUR) (LA COUNTY)................... 1.46
SEPULVEDA CYN AT MULH (LA COUNTY)............ 1.45
BEVERLY HILLS (LA COUNTY).................... 1.42
CRYSTAL LAKE (LA COUNTY)..................... 1.41

For more totals see RRMLOX:
forecast.weather.gov/product.php?site=lox&issuedby=LOX&product=RRM

Isolated showers will linger across LA county through the evening.
For Tuesday, 10-25% chance of showers and thunderstorms across all
four counties mainly focused along the Central Coast. For Wednesday
and Thursday, a slight chance of showers and thunderstorms (10-15%)
will stay confined over the local mountains - Lockwood valley and
eastern San Gabriels. 5% chance or less across rest of the interior.

One key note I want to emphasis is that humidity levels will be
rather extreme across the LA Basin for the upcoming heat focused
Tuesday through Thursday. Wednesday will have the highest risk for
heat illness. Some model projections such as the ECWMF has dewpoint
values in excess of 75 degrees with less cloud cover which would
push the LA Basin area into the WARNING category. However, there
is still quite the spread in dewpoints and cloud cover thus will
stay with heat advisories for now (20-30% chc of an upgrade to an
Extreme Heat Warning). Stay tuned for future updates.

***From Previous Discussion***

Now that the main rain event from Tropical System Marie is behind
us, the focus of the forecast pivots to the the upcoming heat
event. While remnants of Marie will remain well off the
California Coast over the next few days, a ridge of high pressure
will build into the region from the east over the next several
days. Temperatures will trend upwards each day through Wednesday,
when 500 mb heights and the light offshore winds will peak. For
most areas Wednesday will be by far the warmest day of the event,
most noticeably along the Central Coast including Santa Maria and
San Luis Obispo, except the Santa Barbara South Coast may see the
warmest temperatures on Thursday due to an increase in Sundowner
winds in the area.

Heat Advisories are in effect Tuesday through Thursday for Los
Angeles County beaches and coastal valleys, and the Santa Monica
Mountains. Wednesday Heat Advisories are expanded to include the
Ventura County coasts and valleys, the Santa Clarita Valley, and
all of Santa Barbara and San Luis Obispo Counties. Widespread
highs will peak in the 90s (including near some coasts) to low
100s. Due to Marie`s influence on the area, humidity will be
elevated which will significantly increase the HeatRisk and
discomfort. The moisture will impact overnight low temperatures,
which will remain very warm (widespread 70s with even some 80s in
the foothills). Mid and high cloud coverage will serve to moderate
heat impacts at times, and the overall event will be relatively
short compared to other heatwaves we have seen so far this summer. This
heat may feel comparable or even slightly worse to recent heat
waves, especially near the coast. Those working or recreating
outdoors as well as those without air conditioning are advised to
follow the forecast, stay hydrated, and seek cooling centers when
possible. There is around a 20-30 percent chance of the Heat
Advisories being upgraded to Extreme Heat Warnings on Wednesday.
This will depend some on the anticipated cloud coverage. The
coastal areas along the Central Coast are of particular concern on
Wednesday, where temperatures may reach 100 degrees or higher for
some locations (20+ degrees above normal).

Tropical Storm Marie is currently centered 750 miles southwest of
Los Angeles, continuing its northwest movement well offshore of
southern California. Even so, moisture and south swells remain in
the area. There is an ongoing, significant hazard across south
facing beaches, with strong and potentially deadly rip currents
(see coastal hazards for details). As for more rain, there is a
slight chance (5-15%) of thunderstorms focused over LA and Ventura
County through this afternoon, and then tomorrow focused over
Ventura Santa Barbara Counties and the Central Coast (and coastal
waters). This is due to the very high PWATs brought into the
region by Marie, combined with any sources of lift. Minor
scattered shower are possible through Tuesday. Then by Wednesday,
shower and thunderstorm activity will likely become confined to
the highest mountains as the strengthening ridge caps and slightly
dries out mid-levels of the atmosphere.

.LONG TERM (FRI-MON)...07/226 PM.

There is the potential for Heat Advisories to be extended on
Friday, however there is high uncertainty for this time period.
Ridging is favored to continue for the area on Friday, but 500 mb
heights will not be as high as previously, and onshore flow will
be stronger thus increasing the cooling seabreeze. By the weekend,
near normal temperatures appear likely. Troughing off the coast
may reestablish at times, keeping the door open for additional
tropical moisture to shuttle into southwest California.

&&

.AVIATION...08/0112Z.

At 2355Z at KLAX, there was no marine layer. A surface inversion
had a top near 1800 feet, with a temperature of 28 degrees C.

Low to moderate confidence in the Central Coast sites where the
marine layer coverage is lower certainty. Dense fog is likely at
KSMX (60%) and possible (20%) at KSBP. The timing of low CIGs and
VSBY could differ +/- 2 hrs from TAF times. In addition, there is
a slight chance of showers and thunderstorms along the Central
Coast, and portions of Santa Barbara, Ventura and LA Counties 12Z
Tue through 00Z Wed. CIGs and especially VSBY could lower during
any storms that occur, with a chance of brief heavy showers.

KLAX...Moderate confidence in the 00Z TAF. Stratus CIGs are not
expected but there is a slight chance of -SHRA (and a non-zero
chance of -TSRA) between 12Z to 00Z. Any showers could produce
locally gusty winds and brief moderate to heavy rain. No
significant east wind component expected.

KBUR...Moderate confidence in the 00Z TAF. There is a slight
chance of -SHRA (and a non-zero chance of -TSRA) between 12Z to
00Z. Any showers could produce locally gusty winds and brief
moderate to heavy rain.

&&

.MARINE...07/805 PM.

For the waters south of the Channel Islands, there is a slight
chance of thunderstorms through this evening. Any thunderstorm
that storms could produce local gusty and erratic Gale Force
winds and seas, brief heavy downpours, and dangerous cloud-to-
surface lightning. An additional slight chance of thunderstorms
will affect portions of the waters Tuesday, mainly in the western
Santa Barbara Channel and northward.

For the Outer Waters, below Small Craft Advisory (SCA) level
winds and seas are expected into Wednesday, except for local
advisory level gusts around Point Conception each afternoon and
evening. Wednesday night through Friday, SCA winds are likely
much of the time, especially over the southern zones near and
south of Point Conception.

For the Inner Waters north of Point Sal, there is a 60% chance
of SCA winds Thursday afternoon through Friday.

For the Inner Waters south of Point Conception, localized areas of
borderline SCA winds are likely Tuesday afternoon and evening,
nearshore along the LA County coast and through the San Pedro
Channel. The focus for SCA winds will shift to the western Santa
Barbara Channel Thursday into the weekend.

A south swell is impacting the area, although beginning to
subside. This swell may still cause increased currents and surges
in vulnerable harbors. Breaking waves may impact some south facing
harbor entrances, particularly for Ventura and Los Angeles
Counties.

&&

.BEACHES...07/726 PM.

There is a slight chance of thunderstorms across the Los Angeles
County beaches through this evening. Any thunderstorm that forms
could produce local gusty and erratic winds and seas, brief heavy
downpours, and dangerous cloud-to- surface lightning. Additional
thunderstorm chances are expected early Tuesday morning through
the afternoon hours, affecting mainly the Central Coast and Santa
Barbara South Coast, but with a non-zero chance further south.

A south swell from tropical storm Marie is beginning to subside,
but with continued coastal impacts likely through Tuesday. High
surf will affect south- facing beaches of Ventura and Los Angeles
counties, peaking at 4-7 feet with local sets to 8 feet through
Tuesday afternoon. Very strong rip currents will continue as
well. The highest surf is along Zuma Beach and the Long Beach
area. HIGH SURF ADVISORIES remain in place for Los Angeles and
Ventura Counties, with BEACH HAZARDS STATEMENTS in effect for
Santa Barbara and San Luis Obispo Counties.

Moderate coastal flooding has occurred and will continue around
high tides for south facing shores. The actual observed tides
have been running about 6 inches above predictions, with the
evening tides likely near or exceeding 7 feet. As the surf begins
to diminish, the coastal flooding will subside somewhat.

Expect beach erosion, flooded sandy beach areas, bike paths, and
parking lots, as well as low-lying roads. Of particular concern
will be the Alamitos Peninsula area in Long Beach where coastal
flooding will potentially cause local damage to structures near
times of high tide. Other areas of concern the next couple of
days include Catalina Island, and Oxnard to Malibu (including the
Pacific Coast Highway near Point Mugu). COASTAL FLOOD ADVISORIES
remain in effect for Los Angeles and Ventura Counties where the
best combination of tides and waves will occur, but Santa Barbara
and San Luis Obispo Counties could also see some isolated issues.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory in effect from 10 AM Wednesday to 8 PM PDT
      Thursday for zones 38-88-340>358-374-375. (See LAXNPWLOX).
     Coastal Flood Advisory in effect until 11 PM PDT Tuesday for
      zones 87-354-362-366. (See LAXCFWLOX).
     High Surf Advisory in effect until 11 PM PDT Tuesday for
      zones 87-354-362-366. (See LAXCFWLOX).
     Beach Hazards Statement in effect through Tuesday evening for
      zones 340-346-349-350. (See LAXCFWLOX).
     Heat Advisory in effect from 10 AM Tuesday to 8 PM PDT
      Thursday for zones 362-366>373-548. (See LAXNPWLOX).
PZ...NONE.

&&

$$

PUBLIC...Schoenfeld/Black
AVIATION...Ciliberti
MARINE...Black/Lund/Ciliberti
BEACHES...RS/Gomberg/KL/CC
SYNOPSIS...Munroe/Schoenfeld/Ciliberti

weather.gov/losangeles

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