417
FXUS66 KLOX 221619
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
919 AM PDT Wed Oct 22 2025

.SYNOPSIS...22/905 AM.

A low pressure system moving over the area will keep temperatures
on the cooler side day with a chance of showers over the
mountains. Dry and much warmer conditions are expected Thursday
and Friday before cooling returns over the weekend.

&&

.SHORT TERM (TDY-FRI)...22/918 AM.

***UPDATE***

The first salvo from this complex upper low has moved out of the
area to the east and north, and with the possible exception of a
shower or brief thunderstorm over the Ventura/Santa Barbara
mountains this afternoon, the weather today will be relatively
quiet. A second upper low will be passing through this afternoon
giving us that slight chance of mountain showers but otherwise no
other impacts aside from it being a cooler day. The marine layer
deepened as expected to around 2500 feet but the instability in
the low and mid levels likely contributed to the early break up of
the low clouds. However, despite the added sunshine today, the
strong onshore trend of over 5mb will keep highs on the cooler
side today.

***From Previous Discussion***

Decent north flow develops this evening as the northerly return
flow from the departing low sets up. Gusty N winds will develop
through I-5 corridor and western Antelope Vly foothills. Slightly
less strong north winds will also develop across the SBA south
coast. Right now it looks like the wind gusts will come in just
under advisory levels.

A ridge will rapidly build into the state on Thursday. The rising
hgts and northerly offshore flow will join up to bring 4 to 8
degrees of warming to almost all of the area.

Northerly flow will continue Thursday night. Enough to cause some
canyon winds and to scare off the marine layer, but advisory level
gusts are not a concern.

A Chamber of Commerce Day arrives on Friday. The ridging aloft
will continue and hgts will rise to 584 dam. Northerly offshore
flow will persist as well. Look for an additional 3 to 6 degree of
warming under sunny skies. Max temps will end up in the 70s across
the csts and in the 80s in the vlys.

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)...22/258 AM.

Much cooler conditions are slated for the weekend as a trof drives
through the PACNW and sets up NW flow over the state. At one point
an embedded disturbance was fcst to bring some rain to SLO/SBA
counties but that idea had passed and now all that is expected is
partly to mostly skies as mid and high level clouds drift
overhead. Also a switch to onshore flow may bring back some
morning marine layer stratus. Lowering hgts and a return to
onshore flow will bring 2 to 4 degrees of cooling each day to most
areas.

The change of seasons is quite apparent as the weather pattern
becomes much more changeable.

A ridge, fast on the heels of the trof will move in on Monday and
continue into Tuesday. Moderate northerly offshore flow will
develop along with the ridge and Monday will feature gusty
northerly canyon winds. There is not much (if any) upper or
thermal support so its likely that the gusts will not reach
advisory levels. The offshore push should eliminate the marine
layer cloud threat, The rising hgts and offshore push from the
north will also bring 1 to 3 degrees of warming.

The EC favors a Santa Ana pattern on Tuesday with about 5 mb of
offshore flow from both the E and N (still no upper level or
thermal support). The GFS favors a more northerly wind event. Most
ensembles lean towards the northerly wind event solution. Offshore
flow, ridging and plenty of sunshine will bring 3 to 6 degrees of
warming to most cst/vly locations warming them up to 2 to 4
degrees above normal.

&&

.AVIATION...22/1120Z.

At 0721Z at KLAX, the marine layer depth was 1400 feet. There was
an inversion at 1900 feet with a temperature of 17 C, with
multiple inversions above it.

High confidence in TAFs for KWJF and KPMD.

Moderate confidence in TAFs for KSMX, KSBP, KOXR, KCMA. Clearing
times may be off +/- 2 hours and return may be off +/- 3 hours for
KSMX and KSBA. 20% chance for VFR conds to prevail after 18Z at
KSMX and KSBP.

Low confidence in remaining TAFs. Chance for MVFR cigs at KSBA
(30%), KBUR (20%), and KBUR (25%) through 18Z. 30-40% chance for
no low clouds tonight at KSMO, KLAX, and KLGB. Clearing times may
be off +/- 2 hours and return may be off +/- 4 hours.

There is a 10-20% chance for -SHRA and or -TSRA at any site
through the end of the period.

KLAX...Low confidence in TAF. 30% chance for no low clouds this
morning. Otherwise, clearing times may be off by +/- 2 hours and
return of low cloud tonight may be off +/- 4 hours. 15% chance for
-SHRA or -TSRA any from late this morning through tonight. No
 significant east wind component expected thru this morning
 morning, but there is a 30% chance reaching 8 kts between 07Z-17Z
 Thursday.

KBUR...Low confidence in TAF. 25% chance for MVFR cigs through
18Z. 15% chance for -SHRA or -TSRA any from late this morning
through tonight.

&&

.MARINE...22/908 AM.

A shower or thunderstorm will remain possible into the afternoon
for the waters off the Central Coast.

A long period northwest swell will continue to bring Small Craft
Advisory (SCA) 10+ foot seas through this evening to the waters
beyond 20 miles from shore, then likely again Friday through the
weekend.

High confidence in abnormally gusty west winds bringing SCA winds
20-30 knots and choppy seas to the waters south of Point
Conception later today, including all of the Santa Barbara Channel
down to San Pedro. High confidence in winds remaining at SCA
levels Thursday through at least Friday, but returning to a more
traditional coverage area (Central Coast to San Nicolas Island).

&&

.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 1 PM this afternoon to 3
      AM PDT Thursday for zone 650. (See LAXMWWLOX).
     Small Craft Advisory in effect from 1 PM this afternoon to 9
      PM PDT this evening for zone 655. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Thursday for
      zone 670. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Friday for
      zones 673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...MW/Rorke
AVIATION...Lewis
MARINE...RK
SYNOPSIS...MW

weather.gov/losangeles

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

NWS Flagstaff Office