355 
FXUS66 KLOX 201629
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA 
929 AM PDT Mon Oct 20 2025

.SYNOPSIS...19/1154 PM.

Dry and uneventful weather will occur today and Tuesday with high
temperatures a little below normal across the coasts and valleys
and a little above normal across the interior. A deep marine
layer will bring clouds and some drizzle to all of the coasts and
valleys on Wednesday. Max temperatures on Wednesday will fall
dramatically with highs only in the mid 60s to lower 70s across
all of the coasts and vlys. Dry and warmer conditions are slated
for the end of the week.

&&

.SHORT TERM (TDY-WED)...20/928 AM.

***UPDATE*** 

With improving conditions we have let the Dense Fog Advisory over
the Central Coast expire at 9 am. Patchy dense fog may continue 
through 10 or 11 am. 

The focus for today will be looking into the Wednesday storm 
which features mainly low chances for showers or drizzle, although
thunderstorms cannot be ruled out especially across the high 
terrain. 

Other weather highlights include a weakening cold front this
weekend with any potential light rain focused across San Luis
Obispo and northern Santa Barbara Counties. Gusty west to
northwest winds may be a bigger impact with this system.

***From Previous Discussion***

Pretty boring weather day today. Srn CA is under a weak ridge with
587 dam hgts overhead. To the SW a large dry upper low is spinning
and not moving much. Near neutral flow at the sfc has not allow
much in the way of marine layer formation or penetration. The high
hgts have smooshed the marine layer low enough to create pockets
of dense fog across the Central Coast and the Santa Ynez Vly where
a dense fog advisory is in effect until 900 am. Otherwise it will
be sunny day with cooler conditions at the coast due to weaker
offshore.

Not much change on Tuesday the upper low will nudge a little
closer as it begins its trek to the NE. There will be a little
more onshore flow and this should result in a little more marine
layer stratus across the coasts. The increased onshore flow will
bring 2 to 4 degrees of cooling to the csts/vlys while the
interior sees little change in temperatures.

On Tuesday night and Wednesday the upper low to the SW will move
to the NW and will move over the area. The lowering hgts and lift
from the lows approach will quickly deepen the marine layer. It
will likely deepen to around 5000 ft. This will bring low clouds
to all of the csts and vlys as well as the coastal slopes and some
mtn passes. The rapid deepening will also likely bring some
drizzle or even light rain to the csts/vlys esp areas near the 
foothills. There is a non zero chance of some mtn convection in
the late morning or afternoon but the exact chc depends on the
track and timing of the low's passage. Will keep convection out of
the fcst for now and will wait for the hi rez mdl window to open
up. One thing is for certain - the falling hgts and clouds will
bring 2 to 4 degrees of cooling to the csts; 5 to 10 degrees for
the vlys; and 8 to 12 degrees for the mtns and interior. Max temps
will end up 5 to 10 degrees blo normal with only upper 60s to mid
70s for highs across the csts/vlys.

.LONG TERM (THU-SUN)...20/1228 AM.

Two days of dry low impact weather on Thursday and Friday. A weak
ridge will nose into Srn CA from the west and hgts will bump up to
about 584 dam. At the sfc there will be weak onshore flow to the
east and weak offshore flow from the north. Night through morning
low clouds will likely affect most of the coasts, but only the
lower vlys. The rising hgts and increased sunshine will lead to 3
to 6 locally 8 degrees of warming on Thursday and 2 to 4
additionaldegrees on Friday. Friday's max temps will come in 
within a few degrees of normal.

Less confidence in the weekend forecast as a very large trof will
cover the entire west coast. A weak front embedded in this system
will move into and then pass through the state Sat night and
Sunday. The most likely scenario favored by most of the ensembles
and the AI infused EC is for cloudy and dry conditions. But 20 to
30 percent of the ensembles do bring light rain to SLO and SBA
counties. Rainfall amounts, if any, will be under a quarter inch
with inconsequential rainfall rates. Max temps will cool 2 to 4
degrees each day with the increased clouds and lowering hgts. Max
temps by Sunday will mostly see highs in the 70s across the csts
and the vlys. These max temps will be 4 to 8 degrees blo normal.

Looking beyond the 7 day forecast it does appear that a decent
wind event is shaping up for Tue and Wed. On Tuesday a north wind
is possible, but on Tuesday it is looking more and more likely
that the first moderate Santa Ana wind event will occur. Nothing
is for sure with a forecast 10 days out, but it will be monitored.

&&

.AVIATION...20/1122Z.

At 0744Z, the marine layer depth was around 900 feet deep at 
KLAX. The top of the marine inversion was near 1700 feet with a 
temperature around 23 degrees Celsius.

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

Moderate confidence in remaining TAFs. Timing of transition to 
VFR may be off +/- 90 minutes. Arrival of low clouds tonight may 
be off +/- 2 hours. 20-40% chance for brief LIFR-IFR conds at 
KOXR, KSMO, and KLAX through 18Z, highest at LA County Coastal 
sites. 20% chance for no cigs KLGB this morning. Chance for VLIFR
to IFR conds at KSBA (10%) KOXR (25%), KCMA (15%), KSMO (30%), 
KLAX (40%), and KLGB (40%) from 06Z-18Z.

KLAX...Moderate confidence in TAF. 20% chance for vsbys of 
2SM-5SM and OVC004-010 cigs through 18Z this morning. 40% chance 
of 1-2SM vsbys and cigs OVC003-006 between 06Z and 18Z Tues. No 
significant east wind component expected.

KBUR...High confidence in TAF.

&&

.MARINE...20/831 AM.

Patchy dense fog is currently observed across portions of the 
coastal waters and is expected to last into late this morning. 
Please refer to the Marine Weather Statement for more 
information.

A moderate to long period northwest swell will continue to bring  
7-11 foot seas to the outer waters and nearshore waters along the
Central Coast through the week. A Small Craft Advisory (SCA) has 
been issued for this afternoon through late tonight as seas are 
expected to reach 10-11 feet for the outer waters adjacent to the 
Central Coast more than 20 NM away from the coast. Period of SCA
level seas will continue off and on through the week. Seas will 
begin to increase to 11-13 feet late Friday through the weekend. 
Seas are expected remain relatively small inside the Southern 
California Bight, although steep and choppy wind waves will occur 
Wednesday.

High confidence in winds remaining remaining relatively light 
through Wednesday morning, then northwesterly winds will increase 
to 20-30 knots across the waters south of Point Conception, 
including the inner waters. Winds inside the Southern California 
Bight will decrease late Wednesday night, but SCA level 
northwesterly winds will continue across the outer waters and 
expand to the north Thursday through Friday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory in effect until 9 PM PDT Wednesday for
      zones 340-346. (See LAXCFWLOX).
PZ...Small Craft Advisory in effect until 9 PM PDT this evening
      for zones 670-673. (See LAXMWWLOX).

&&

$$

PUBLIC...Rorke
AVIATION...Lewis
MARINE...Lewis
SYNOPSIS...30

weather.gov/losangeles

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