830
FXUS66 KLOX 291001
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
301 AM PDT Tue Sep 29 2026

.SYNOPSIS...29/227 AM.

Beach impacts from Tropical Cyclones well south of the region are
expected today in the form of high surf, beach erosion, and
possible coastal flooding. A major heat wave will begin to develop
today and will peak Friday and over the weekend with dangerously
hot temperatures and periods of weak Santa Ana winds.

&&

.SHORT TERM (TDY-THU)...29/227 AM.

The upper low is currently over SE CA and is headed to the east.
It will continue to bring northerly flow aloft to Srn CA through
the day. At the sfc building sfc high pressure to the NNE will
bring about 4 mb of offshore flow from the north and 1 to 2 mb
from the east. The offshore flow and reinforcing upper level flow
will bring low level advisory gusts (35 mph to 45 mph) to the mtns
as well as the SBA south coast. Local gusts to 35 mph will affect
portions of LA and VTA counties as well. The offshore flow and
rising hgts will bring a warming and drying trend to entire area.
Most areas will see a 4 to 8 degree bump up in temps today with
max temps topping out in the 80s across the csts and upper 80s to
mid 90s in the vlys.

For Wednesday and Thursday an east Pac ridge will build into the
state and raise hgts to 588 dam. There will only be weak offshore
flow Wednesday morning with onshore flow in the afternoon. By
Thursday there will be onshore flow through the day. An eddy is
forecast to spin up each evening which will likely bring some
patchy low clouds to the LA beaches while the onshore flow to the
east will create some morning stratus across the portions of the
Central Coast. The weaker offshore flow on Wednesday will lead to
1 to 3 degrees of cooling across the csts and vlys, but the
increased hgts will lead to about 5 degrees of warming for the
mtns and far interior. Despite the better onshore flow on Thursday
the increased hgts and subsidence from the upper will allow all
areas to warm 2 to 4 degrees with the only exception being the
Central Coast which will see little change. Look for 80s and and
few 90 degree readings across the csts on Thursday with the vlys
reaching the lower to mid 90s. These max temps are 4 to 8 degrees
above normal.

.LONG TERM (FRI-MON)...29/228 AM.

As has been mostly the case for both August and September the
forecast focus will be on the heat. A large dome of high pressure
will sit atop of the state and bring 590 dam hgts to Srn CA. The
ridge does break down on Monday but will only drop to 588 dam. The
forecast problem lies in the sfc pressure gradients where there
remains a large range of possibilities. Right now the most likely
scenario is for there to be be 2 or 3 mb of offshore flow in the
mornings and 1 mb of onshore flow in the afternoon. This would
result in highs in the 80s and lower 90s across the csts and mid
90s to 102 degrees in the vlys. These kind of max temps are 10 to
15 degrees above normal. There is a 30 to 40 percent chc that
there will be stronger offshore flow in the mornings and no
onshore flow in the afternoons. This scenario would generate a
long duration 3 day heat event with highs 90 to 100 across the
csts and 100 to 110 degrees in the vlys. The vlys will have the
typical low humidities assoc with offshore flow. There could be
more humidity across the csts, however, if the offshore push is
not that strong due to the high sea sfc temps. Heat headlines are
a near certainty for this period the only question is weather they
will be heat advisories or heat warnings.

There will be a few degrees of cooling on Monday as the ridge
relaxes some, but max temps will remain 10 or more degrees above
normal.

The EC-AI mdl remains very steadfast in its prediction that well
above normal temps will persist through the 1st 2 weeks of
October.

&&

.AVIATION...29/0929Z.

At 0822Z at KLAX, there was no marine layer or inversion.

High confidence in VFR TAFs for KPRB, KWJF, KPMD, KSBA, KBUR, KVNY,
and KCMA.

Good confidence in remaining TAFs with a only a 10 percent chc of
IFR cigs 12Z-16Z.

KLAX...Good confidence in TAF. There is a 10 percent chance of
BKN008 conds 12Z-16Z. High confidence in no significant east wind
component.

KBUR...High confidence in VFR TAF.

&&

.MARINE...29/151 AM.

High confidence in Small Craft Advisory (SCA) winds and steep
seas affecting the outer waters through late tonight. Local Gale
Force gusts will be possible at times, especially this afternoon
and evening for the outer waters south of Point Conception and
north of Point Sal. Nearshore waters along the Central coast will
see SCA winds and steep seas this afternoon and evening.

For the inner waters south of Point Conception, SCA winds are
expected across much of the Santa Barbara Channel and portions of
the inner waters adjacent to Los Angeles and Orange Counties
this afternoon into tonight.

Southerly swell from Polo (SSE) will continue to affect the
region through today and tonight. These swells will create larger
waves and surf nearshore, which could impact some south exposed
harbor entrances.

Conditions are likely to improve to below SCA levels Wednesday
into next weekend, except for occasional northwest SCA winds near
Point Conception in the afternoon/evening hours.

&&

.BEACHES...29/151 AM.

Southerly swell from Hurricane Polo will continue to affect our
coastline today. This swell timing will line up with very high
tides though this morning. Some south-facing shores are more
vulnerable because of the lingering erosion effects from Hurricane
Marie earlier this month.

Surf heights across Los Angeles and Ventura Counties around 4-7
feet are expected today, while the Santa Barbara south coast
should see surf in the 2-4 foot range. High tides are peaking
around 7 feet (MLLW) in the late morning hours - which is higher
by almost a foot over astronomical tides due to ongoing effects of
El Nino.

While this swell is slightly smaller than the swell from Marie,
there is still significant concern of Coastal Flooding over
vulnerable south-facing beaches. The areas of most concern include
Avalon, Long Beach, Malibu, and to a lesser extent Santa Barbara.

South-facing beaches should plan for shallow flooding of seawater
over low lying beach walkways, parking lots, and roads as well as
potential for significant beach erosion. Very localized damage to
structures is possible in the most vulnerable areas. Minor tidal
overflow may affect west facing beaches due to very high tides.

Beach Hazards Statements (BHS) are in effect for Santa Barbara
south coast through Wednesday. A Coastal Flood Advisory and High
Surf Advisory are in effect for LA and Ventura through Tuesday
afternoon. A BHS may need to be issued for the LA and Ventura
coasts for Tuesday afternoon through Wednesday (lining up with
Santa Barbara) due to the very high tides.

The East Pacific Hurricane Season is forecast to remain active,
with with additional southerly swells and surf/coastal flooding
impacts possible again next week.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Coastal Flood Advisory in effect until 5 PM PDT this
      afternoon for zones 87-354-362-366. (See LAXCFWLOX).
     High Surf Advisory in effect until 5 PM PDT this afternoon
      for zones 87-354-362-366. (See LAXCFWLOX).
     Wind Advisory in effect until 6 AM PDT early this morning for
      zones 349>353-376>378. (See LAXNPWLOX).
     Beach Hazards Statement in effect through Wednesday afternoon
      for zones 349-350. (See LAXCFWLOX).
PZ...Small Craft Advisory in effect from 2 PM this afternoon to 11
      PM PDT this evening for zone 645. (See LAXMWWLOX).
     Small Craft Advisory in effect from 2 PM this afternoon to 1
      AM PDT Wednesday for zones 650-655. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Wednesday for
      zones 670-673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Rorke
AVIATION...Rorke
MARINE...Phillips
BEACHES...Phillips
SYNOPSIS...MW

weather.gov/losangeles

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