FXUS66 KLOX 151848
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
1148 AM PDT Tue Oct 15 2024

Updated Aviation Discussion

.SYNOPSIS...15/924 AM.

Cool temperatures along the coast and above normal temps at
inland locations today. An upper level low will bring widespread
cooling and possible drizzle on Wednesday and Thursday. Moderate
to locally strong northwest to north winds will shift to the
northeast by Friday and last through the weekend, bringing warm
and dry conditions to coastal and valley areas.

&&

.SHORT TERM (TDY-THU)...15/945 AM.

***UPDATE***

The 24-hour temperature change of cooler along the coast and
warmer at far inland locations is indicative of the trend
expected for today when the coasts are expected to finish 4-8
degrees below normal and the interior maybe 4-8 degrees warmer. No
impactful changes to the previous discussion, with wind and
possible light rain or drizzle being the focus of the forecast
period.

***From Previous Discussion***

This morning's marine layer is about 1500 ft deep and a 3mb push
to the east along with a weak eddy have brought stratus to all of
the coasts and most of the vlys. Clearing will be fairly slow
today but by late morning most of the area should be sunny. The
low clouds will likely be hanging just off the coast. A weak ridge
will push in to the area today and the rising hgts and subsidence
assoc with it will raise most temperatures a few degrees compared
to ydy. A little offshore push across the Central Coast will bring
about 6 degrees of warming to most locations there while the
deeper than normal marine layer will cool the coasts south of Pt
Conception by few degrees. The deep marine layer will bring a
split personality to the temperatures today with the csts/vlys 4
to 8 degrees blo normal and the interior 4 to 8 degrees above
normal.

A weak trof will move into and across the state late tonight and
through the day Wednesday. The lowering hgts and weak lift form
this trof will lift the marine layer to over 3000 ft and stratus
clouds will cover all of the csts/vlys and xtnd up the coastal
slopes. There will be enough lift to produce areas of drizzle esp
south of Pt Conception. Clearing Wednesday will be a slow to no
affair with many coastal locations seeing no sun at all. Max temps
will fall 2 to 4 degrees across the csts/vlys and 4 to 8 degrees
across the interior. Most csts will see max temps in the 60s and
the vlys will see 70s.

Decent NW to N winds will develop late in the afternoon or early
in the evening in the wake of the weak trof. The strongest winds
will be in the Antelope Vly and its western foothills as well as
the SBA south coast (esp the western half) wind advisories are
likely (70 percent chc) for these two areas will gusts from 45 to
50 mph.

A weak eddy is also forecast to form early Thursday morning and
this will bring another round of low clouds to the csts/vlys of
VTA and LA county and probably SE SBA county. Strong NW winds will
push marine layer into the Santa Ynez vly where stratus will form
and then back-build into the rest of western SBA county. Drizzle
will again be a morning concern. The deep marine layer and
increasing onshore flow to the east will keep the stratus (perhaps
turning to stratacu in the afternoon) going through most of the
day across VTA and LA counties.

Most areas will see another 3 to 6 degrees of cooling (not the SBA
south coast, however, where N to S offshore flow will bring 3 to 6
degrees of warming). Max temps across the csts and vlys will only
be in the 60s and lower 70s or 8 to 12 (locally 15) degrees blo
normal.

An inside slider is fcst to move down the NV/CA line Thu night and
early Friday morning. There will be another round of strong winds
across the Antelope Vly and SBA south coast. There is a small (15
to 20 percent) that the weak trof assoc with the inside slider
will interact with the deep marine layer and produce some light
rain across LA county late in the evening or in the predawn hours
Friday. Rainfall amounts would not amount to anything much a
couple hundredths as best.

.LONG TERM (FRI-MON)...15/316 AM.

There is much better agreement between the deterministic mdls and
the ensemble spreads have shrunk as well. So there is now decent
confidence in the long term forecast.

The inside slider will swoop into AZ Friday afternoon and will set
up a burst of northerly flow across the area. A low level 70 mph
700 mb jet will run down the backside of the low and over SBA
county. The 12Z N to S gradient will turn rapidly offshore to
near 5 mb. There is not much of a sfc push from E to W and the
upper support is mostly N to S, so this will not be a Santa Ana
wind event it will be a strong N wind event. Localized gusts
between 55 and 65 mph are likely over the most favored mountains
and foothills including southern Santa Barbara County, the I-5
Corridor, and the Antelope Valley. The north flow will bring 5 to
10 degrees of cooling to the interior. The csts/vlys will warm 4
to 8 degrees as the winds downslope and warm from the mtns.
Despite the warming almost all of the area will be several degrees
blo normal (many degrees across the interior)

Look for a little bit of NE winds on Saturday morning. Very likely
under advisory levels. Still enough to eliminate the threat of
marine layer clouds. hgts will rise as a weak ridge will move in
from the west. The rising hgts and offshore flow will combine to
bring 4 to 8 degrees of warming to most of the area.

Mdl disagreement begins to creep in for the Sun/Mon fcst but
either way the weather will be benign. If the GFS solution is
right max temps will end up a little warmer than fcst. There will
be weak offshore flow in the morning and there will not be much in
the way of morning low clouds. The much weaker onshore flow will
bring noticeable cooling to the csts/vly on Sunday with 3 to 6
degrees of warming for the interior due to further hgt rises. Max
temps will change little on Monday.

&&

.AVIATION...15/1847Z.

At 1820Z at KLAX, the marine layer was around 3000 ft deep.

High confidence in TAFs for KPMD and KWJF.

Moderate confidence in coastal and valley TAFs. There is a 20-30%
chance cigs do not clear today for Ventura and LA County coastal
sites, and a 30% chance of a few hours of VFR conds at KSBA from
22Z-01Z. Timing for the return of cigs may be off by +/- 90
minutes for coastal sites, and +/- 3 hours for KPRB, KBUR, and
KVNY.

KLAX...Moderate confidence in TAF. There is a 30% chance cigs do
not clear today. There is a 15% chance of an east wind component
reaching 6 kt from 13Z-16Z.

KBUR...Moderate confidence in TAF. Flight cats may be off by 1
category at times, and the timing for the return of cigs may be
off by +/- 3 hours.

&&

.MARINE...15/229 AM.

Across the Outer Waters (Central Coast to San Nicolas Island),
Small Craft Advisory (SCA) level conditions or higher are
expected much of the time through Fri night, with the exception
for brief lulls in the late overnight hours in the southern half
of the Outer Waters thru Wed. By late Wed, there is a 20-30%
chance of Gale Force winds for the northern waters off the Central
Coast, followed by a 50-70% chance of Gales for all the Outer
Waters Thurs morning through Fri night. Strongest winds are
expected Thurs evening/night. Seas of 10 to 15 feet are expected
Thu and Fri.

Nearshore along the Central Coast, SCA conditions are likely
during the afternoon/evening hours today and Wed (60-70% chance),
and then continuously from Thu through Fri night. There is a 20%
chance of Gale Force winds Wed evening and a 40-50% chance
Thursday thru Friday night. Seas 10 to 15 feet possible Thursday
and Friday for the western portion.

Across the Santa Barbara Channel, there is a 30% chance of SCA
level winds across the western/southern portions of the Channel
during the afternoon/evening hours today, and a 50-60% chance on
Wed during the same time frame. SCA winds are likely (50-70%
chance) Thu through Fri, with a 20-30% chance of Gales Thurs thru
Fri in the far western portion of the Channel. Seas are likely to
peak around 7 to 12 feet across the channel Thursday and Friday.

For the nearshore waters off the Los Angeles and Orange County
coasts, high confidence in winds and seas staying under SCA levels
through Thurs morning. Thurs afternoon through Fri is a 40-50%
chance of NW-N SCA winds and steep seas. Fri night into Sat
morning, winds will shift to the NE, with a 20-30% chance of
reaching widespread SCA level. Seas of 6 to 10 feet will be
possible Thursday night into Friday.

Overall, winds and seas are trending to be sub-Advisory over the
weekend, with the exception of the southern inner waters Sat.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory in effect until 3 AM PDT Wednesday for
      zones 340-346. (See LAXCFWLOX).
PZ...Small Craft Advisory in effect until 9 AM PDT Wednesday for
      zone 645. (See LAXMWWLOX).
     Small Craft Advisory in effect until 9 AM PDT Thursday for
      zones 670-673-676. (See LAXMWWLOX).
     Gale Watch in effect from Thursday morning through late
      Friday night for zones 670-673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Rorke/jld
AVIATION...Schoenfeld
MARINE...Lewis/Schoenfeld/Smith
SYNOPSIS...jld

weather.gov/losangeles

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