830
FXUS66 KLOX 220257
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
757 PM PDT Tue Oct 21 2025

.SYNOPSIS...21/129 PM.

A low pressure system will move over the area later tonight and
Wednesday. It will deepen the marine layer and may create some
light showers and possibly even a thunderstorm. Temperatures will
be much cooler as well. Dry and much warmer conditions are
expected Thursday and Friday before cooling returns over the
weekend.

&&

.SHORT TERM (TUE-FRI)...21/757 PM.

***UPDATE***

Initial wave of mid level moisture has sprung convective showers
on the area, but only one offshore of Morro Bay managed to produce
a few lightning strikes. Rainfall, if any, has been light given
dry lower level air that had to be overcome. We`ll likely see a
break behind this activity by midnight, especially Los Angeles and
Ventura Counties. Further northwest into Santa Barbara and San
Luis Obispo Counties, the closer proximity of the approaching
storm, maintains a slight chance of showers or thunderstorms
overnight.

***From Previous Discussion***

The forecast for the next several days can best be described as
changeable. To start with, an upper low that has been spinning
several hundred miles southwest of LA will finally move onshore
later tonight into Wednesday somewhere between Santa Barbara and
San Simeon. The main impact most will notice is a significant drop
in temperatures as onshore flow returns, creating a 2000-3000
foot marine layer. Some areas may get some morning drizzle out of
the marine layer, but there is also a chance for an isolated
thunderstorm or two, mainly north of Pt Conception and in the
mountains as the upper low slowly traverses the area through the
afternoon. Any shower activity is expected to finish up by late
afternoon/evening, with again most of that being in the mountains
and northern areas.

With the low moving east of LA County Wednesday night, high
pressure is expected to develop behind it along with weakening
onshore flow, creating a rapid warm up back into the 80s in the
valleys and Downtown LA by Thursday and Friday and 70s most
everywhere else except the beaches north of Pt Conception.

.LONG TERM (SAT-TUE)...21/221 PM.

The topsy-turvy weather pattern will continue into the weekend and
through next week. A large upper trough will develop across the
Pac NW over the weekend, pushing the high east and bringing back a
moderate onshore flow that will help drop high temperatures 5-10
degrees in most areas. Will likely see the marine layer returning
as well.

Following that system a strong high pressure ridge will develop
over the eastern Pacific and West Coast areas. Initially this will
result in a strong north to south gradient Sunday night into
Tuesday along with good support aloft creating the potential for
at least advisory level wind gusts in the mountains, the Central
Coast, and southern Santa Barbara County as well as much of the
coastal waters.

Towards the end of that period around Tuesday and continuing into
Wednesday there are increasing signs of what could be at least a
moderate Santa Ana wind event developing as that trough pushes
into the Great Basin while at the same time high pressure
continues to build over the West coast. Some of the ensemble
solutions are already indicating northeast wind gusts between 30
and 50 mph next Tuesday and Wednesday. And with strong high
pressure in place with moderate offshore flow we could be looking
at highs well into the 80s and 90s across coast and valleys.

&&

.AVIATION...22/0106Z.

At 23Z at KLAX, there was no marine layer. There was a surface
based inversion to 2900 feet with a maximum temperature of 21
degrees C.

There is potential for a short-duration showers the TAF sites
00Z through 06Z. Highest confidence for Ventura TAF sites and
northward.

Following 06Z, high confidence in KWJF and KPMD. Low confidence
after 06Z Wed for remaining sites due to uncertainty of marine
layer cig height (+/- 500 feet) and timing (+/- 4 hours) as a
cutoff low works its way into Southern California, which should
provide significant lift to the marine layer. Drizzle will be
possible with clouds, and there will be a 10% chance of VSBY
briefly dropping to 1/2SM-2SM between the hours of 06Z-16Z Wed.
There is a 30% chance of BKN006-BKN015 cigs at KSBA between
06Z-16Z Wed.

KLAX...Low confidence in TAF overall. High confidence in return
of low clouds tonight, but low confidence in cig heights (+/- 500
feet) and timing (+/- 4 hours). There is a 10% chance for brief
showers before 06Z. No significant east wind component expected.

KBUR...Low confidence in TAF overall. There is a 10% chance for
brief showers before 06Z. High confidence in return of cigs
tonight, but timing may be off +/- 4 hours and min cig heights may
be off +/- 500 feet.

&&

.MARINE...21/1247 PM.

A long period northwest swell will continue to bring 10-14 foot
seas to the outer waters and nearshore waters along the Central
Coast into early next week, but a relative lull is likely late
Wednesday into Thursday before another long period swell arrives,
increasing seas to 12-14 feet into early next week. Observed wave
heights have been well over model guidance, thus the Small Craft
Advisory (SCA) has been extended through late Wednesday, with a 20
percent chance to be extended continuously through the weekend.

Northwest winds will increase to 20-30 knots Wednesday across the
waters south of Point Conception, including the Santa Barbara
Channel and possibly the inner waters adjacent to Los Angeles and
Orange counties. Choppy, short period wind waves will occur across
the Southern California Bight Wednesday afternoon through the
late night hours. A SCA has been issued for the Santa Barbara
Channel, and there is a 50 percent chance that one will be needed
for the inner waters adjacent to LA and Orange Counties Wednesay
evening.

Winds will decrease over the inner waters south of Point
Conception Wednesday night but will expand to the remainder of the
outer waters and potentially the nearshore waters adjacent to the
Central Coast Thursday through at least Friday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory in effect until 3 AM PDT Thursday for
      zones 340-346. (See LAXCFWLOX).
PZ...Small Craft Advisory in effect from 3 PM Wednesday to 3 AM
      PDT Thursday for zone 650. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Thursday for
      zones 670-673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...MW/RM
AVIATION...Phillips/Schoenfeld
MARINE...Lewis/Schoenfeld
SYNOPSIS...MW

weather.gov/losangeles

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

NWS Flagstaff Office