095
FXUS66 KLOX 050514
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
1014 PM PDT Fri Oct 4 2024

.SYNOPSIS...04/751 PM.

Extended period of hot conditions will continue over the valleys
and mountains into Tuesday, hottest Saturday through Monday.
Widespread cooling Tuesday through Friday. Low clouds will
continue to moderate the coastal areas, with dense fog and low
visibilities at times.

&&

.SHORT TERM (FRI-MON)...04/805 PM.

***UPDATE***

No significant changes to the forecast this evening. Models
continue to advertise weakening of the onshore flow Saturday along
with warming aloft which will be squashing the marine layer a
little more. Friday temperatures ended up being very close to the
NBM 95th percentile forecast, indicating the pattern is firmly on
the higher end of the possible outcomes and see no reason to veer
from that idea for Saturday and likely Sunday as well. Made some
minor edits to the highs for Saturday to follow closely with the
95th percentile forecast, which in most areas was within a degree
or two of the previous forecast.

Still keeping an eye on the mid level moisture offshore associated
with an upper low that has been producing some lightning about
500nm southwest of Pt Conception. Can`t completely rule out an
isolated shower north of Pt Conception but chances are certainly
under 10%.

***From Previous Discussion***

The onshore pressure gradient trends today will turn slightly
offshore tomorrow with slight ridging aloft. As a result, the
brief break in the heat today will be followed by another warm up
over the valleys and lower mountains for Saturday through Monday.
While temperatures will not reach the levels we experienced
earlier this week, expected highs will still be 10 to 20 degrees
above normal. Excessive Heat Warnings will remain in play without
any changes, with the focus over the inland valleys and lower
mountains. Decided to add Heat Advisories to the Santa Ynez Valley
and inland San Luis Obispo Central Coast for the same period as
well. With any offshore flow staying in the mountains and inland
valleys, there is little reason to think that the low clouds and
fog will go away with this event. Most coastal areas as a result
will remain warm but not hot with no plans at this time to add any
Heat Advisories or Warnings. If the marine layer goes poof and
erodes away, this plan will have to be reconsidered. The marine
layer will shrink however, and dense fog will become a significant
travel issue with very low visibilities.

.LONG TERM (TUE-FRI)...04/144 PM.

Relief from the heat is on the way. High pressure aloft will slow
break down as pressure gradients trend onshore. While Tuesday
will remain rather warm, and will remain above normal all week,
temperatures will steadily drop each day through Friday.

&&

.AVIATION...05/0136Z.

Due to a data outage, current marine layer and inversion height
data is not available for KLAX.

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

High confidence in KBUR. There is a 10% chance of VLIFR to LIFR
cigs/vsbys from 07Z until 12Z.

Low confidence in remaining TAFs. VLIFR conds are possible at all
coastal TAF sites, with best chances north of Pt Conception, and
lowest in the LA Basin. VSBYs may vary between categories from
VLIFR to low IFR through 17Z. Cigs arrival times may be 2-4 hours
later than forecast.

KLAX...Low confidence in 00Z TAF. There is a 30% for cigs
VV001-VV002 and/or vsbys 1/4SM to 1/2SM between 06Z and 15Z.
Arrival of cigs may be delayed by 2-4 hours from current TAF. No
significant east wind component is expected.

KBUR...High confidence in 00Z TAF. There is a 10% chance of VLIFR
to LIFR cigs developing from 06Z to 15Z.

&&

.MARINE...04/1011 PM.

For the Outer Waters (off the Central Coast south to San Nicolas
Island), high confidence in the current forecast through Sunday,
as winds will remain below SCA (Small Craft Advisory) levels. For
late Sunday/early Monday through at least Friday, there is a
50-70% chance of SCA level winds and seas. There is a 20% chance
of low end Gale Force winds Monday thru Wednesday.

For the Inner Waters north of Point Sal, high confidence in winds
and seas remaining below SCA levels thru Sunday. Chances for SCA
winds start Tuesday, and are again possible during the afternoon
thru evening hours on Wednesday through at least Friday. There is
a 20% chance for gales Friday afternoon.

For the Inner Waters south of Point Conception moderate to high
confidence in winds and seas remaining below SCA levels through
Sunday morning. There is a 30% chance for SCA level winds during
the afternoon and evening hours on Sunday near Point Mugu and
thru the San Pedro Channel. There is a 20-30% SCA winds for
western portions of the Santa Barbara Channel for Tuesday thru
Wednesday during the afternoon thru evening hours.

A shallow marine layer will continue to generate patchy dense fog
across portions of the coastal waters over the weekend,
especially in the overnight thru morning hours. Visibilities of
one nautical mile or less can be expected.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Excessive Heat Warning remains in effect from 10 AM Saturday
      to 8 PM PDT Monday for zones
      38-88-342>345-351>353-356>358-369>376-378>380-548. (See LAXNPWLOX).
     Heat Advisory in effect from 10 AM Saturday to 8 PM PDT
      Monday for zones 341-348. (See LAXNPWLOX).
PZ...NONE.

&&

$$

PUBLIC...MW/Kittell
AVIATION...Phillips
MARINE...Phillips/Lewis
SYNOPSIS...RK

weather.gov/losangeles

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