258
FXUS66 KLOX 240029
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
529 PM PDT Mon Sep 23 2024

.SYNOPSIS...23/523 PM.

Low clouds and fog will affect coastal areas through the week
with near normal temperatures. Dense fog is likely near the coast
through at least Tuesday. Inland temperatures will remain above
normal through the week, warmest through Tuesday. Otherwise,
quiet weather is expected through the week.

&&

.SHORT TERM (TDY-THU)...23/217 PM.

Low clouds and fog remain parked along the coast this afternoon,
with webcams showing very low visibilities still on the Central
Coast. With no clearing trend apparent to the north, and little
change expected to the onshore push and marine layer depth
tonight, went ahead and issued a Dense Fog Advisory for the
Central Coast and Santa Ynez Valley for later this evening through
Tuesday morning. Other coastal areas may need to be added based
on how the marine layer evolves tonight. Inland of the coasts,
temperatures are up 5 to 10 degrees, with a handful of 100 degree
readings already around the current hot spot around the Santa
Clarita Valley.

Temperatures should be very similar on Tuesday compared to today
with little change to the upper level pattern and an onshore
pressure trend holding off until later in the day. Over the
coastal areas, any trends tomorrow will be based on the
unpredictable behavior of the marine layer. There is good reason
to believe however that temperatures will lower further from Santa
Barbara to Malibu as an the south-to-north pressure trends up,
which usually spells little to no cloud clearing for that area.

A weak low pressure area, currently about 250 miles west of the
Central Coast will change little through tomorrow, then pull
closer towards San Fransisco on Wednesday, before settling back to
just off the coast by Thursday. This will result in some cooling
to the region, most noticeable over the mountains and valleys.
This should also kick off some Sundowner winds with gusts in the
25 to 40 mph range. The change in the upper level pattern and the
Sundowner winds will modify the low cloud pattern and behavior.
Expecting the marine layer to deepen, which will limit some of the
dense fog threat, but the winds will likely bring more hours of
clearing and a later arrival from Santa Barbara to Malibu.

.LONG TERM (FRI-MON)...23/220 PM.

The weak low just off the coast will push further off the coast
on Friday, as a peak-a-boo high to the east pushes closer to
California. This, along with some indications of weaker onshore
flow may bring a few degrees of warming to inland areas.

While fairly benign conditions will continue Saturday into next
week, some of the finer details are a bit muddled. All of the
projections show a trough moving through the Pacific Northwest,
which would pull the weak low parked just off our coast through
southwest California and to the east. A fair amount of the
projections (mix of EPS and GEFS solutions) have this all
happening sometime over the weekend, while the slim majority (mix
of EPS GEFS Canadian) keep the status quo through the weekend with
the change happening Monday or Tuesday. Until that happens,
expected little change to the conditions on Friday, with near
normal temperatures and breezy Sundowners. After that shift
happens, expect further cooling, marine layer expansion, and gusty
onshore flow over the interior areas.

&&

.AVIATION...24/0021Z.

At 2300Z at KLAX, the marine layer was 1000 ft deep. The top of
the inversion was near 2900 ft with a temperature of 32 deg C.

High confidence in desert and KPRB TAFs.

Low to moderate confidence in the KSBP and KSMX TAFs. Timing of
flight cat changes could be off by +/- 2 hours. There 30% chance
of VLIFR conds at both sites between 06Z-15Z.

Low confidence for all other TAFs. Timing of flight cat changes
could be off by +/- 2 hours. Cigs could scatter and reform at
KSBA, KOXR, KSMO, and KLAX through 06Z, and there is a 30-40%
chance of VLIFR conds 06Z-16Z. There is a 30% chance of VLIFR
conds at KCMA 06Z-15Z. There is a 30-40% chance of conds
remaining VFR at KBUR and KVNY, if cigs do arrive, there is a 30%
chance of VLIFR conds after arrival through 16Z.

KLAX...Low confidence in the 00Z TAF. There is a 30-40% chance of
1/2SM FG and VV002, with a 20-30% chance of 1/4SM FG and VV002
cigs 10Z-15Z. High confidence in no significant easterly wind
component.

KBUR...High confidence in TAF through 10Z, then low confidence.
Timing of flight cat changes could be off by +/- 3 hours. There
is a 40% chance of 1/2SM FG VV002 conds 11Z-15Z, with a 20%
chance of 1/4SM FG VV002.

&&

.MARINE...23/213 PM.

High confidence in the current forecast through early Thursday,
then moderate confidence thereafter. Winds and seas will remain
below Small Craft Advisory (SCA) levels through early Thursday,
except for a low-to-moderate (20-30 percent) chance of local SCA
level W-NW wind gusts in the vicinity Point Conception, near Point
Dume and into the San Pedro Channel each afternoon and evening
through Wednesday. There is a moderate (40-50 percent) chance of
SCA level winds Thursday afternoon through Friday for the waters
beyond 10 NM offshore along the Central Coast southeast to San
Nicolas Island. Additionally, there is a 30 percent chance of SCA
level seas across the outer waters building over the weekend.

A shallow marine layer over the coastal waters will bring at
least patchy dense fog to the coastal waters at times through
Wednesday morning. A marine weather statement is in effect through
noon Tuesday, but there is a likely chance that areas to
widespread dense fog will redevelop over the coastal tonight
through Tuesday morning.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Dense Fog Advisory in effect from 9 PM this evening to 10 AM
      PDT Tuesday for zones 340-341-346>348. (See LAXNPWLOX).
PZ...NONE.

&&

$$

PUBLIC...Kittell
AVIATION...Lund/Smith
MARINE...Hall/Lund
SYNOPSIS...Kittell/Smith

weather.gov/losangeles

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