000
FXUS66 KLOX 070529
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
1029 PM PDT Thu Oct 6 2022

updated aviation discussion

.SYNOPSIS...06/542 PM.

High pressure aloft over the region will bring a warming trend to
Southwest California Friday and Saturday. Temperatures will be
warmer than seasonal levels over the weekend, then a cooling trend
is expected next week as low pressure develops over California.

&&

.SHORT TERM (THU-SUN)...06/824 PM.

***UPDATE***

Once again it was another early return of low clouds to the
coastal portions of the forecast area. The marine layer is around
400 ft deep over the Central Coast and 1500 feet deep over the LA
basin, comparable to this time last night. Combined with not much
change in the overall synoptic pattern, expecting a similar
stratus forecast. Clouds should be able to march into the coastal
valleys again tonight. There is a chance that the inland
penetration over LA and Ventura Counties may not be as far Friday
morning as gradients are expected to trend about 1 mb offshore.
There is once again a chance for patchy dense fog to develop over
the Central Coast overnight into Friday morning with the much
shallower marine layer. As for winds, again there are some breezy
northerly winds across the Santa Ynez range this evening. Winds
should remain fairly benign with gusts 30 mph or less. However, a
couple isolated spots are a bit gustier such as Refugio and
Montecito Hills. Also in the wind department is the potential for
breezy offshore winds over the mountains and wind-prone valleys of
LA and Ventura Counties thanks to the offshore trend. Gusts
should likely stay below 25 mph. There will likely be better
clearing Friday morning thanks to offshore trends. However, a
strong inversion may help keep clouds around some beaches into the
afternoon. With better clearing, temperatures should warm a few
degrees over coastal areas, but stay similar to today over the
valleys. Weak offshore flow should also pump temperatures up a few
degrees over the wind-prone areas of LA and Ventura Counties.
Like today, the best moisture and instability will remain to our
south in association with the upper-level low that has been
anchoring to northwestern Mexico. So could see more cumulus
buildups over the mountains, but likely no thunderstorms.

***From Previous Discussion***

Most of the short range ensemble solutions indicate a 1-3 degree
warmup Saturday with a very light offshore trend. Sunday very
similar but likely just a touch cooler in most areas. Thunderstorm
chances over the eastern San Gabriels have been removed from the
forecast as models are now trending drier. There is still some
instability with the upper low to the south and there will likely
be some cumulus over the mountains, but just not enough moisture.

.LONG TERM (MON-THU)...06/153 PM.

On Monday the upper low over northern Mexico is nudged to the east
as another upper low drops down out of the west coast trough and
into northern California. This one has a little more energy and
will likely bring additional cooling with it through at least mid
week. However, most of the ensembles have steered away from the
deep cutoff low solution and more towards a weak and dry upper low
that will do nothing more than just cool us down to around 5
degrees below normal by Wednesday and increase the marine layer
coverage. The uncertainty now is with how long this low will
linger over southern California. Both the GFS and ECMWF
deterministic runs keep it here through next weekend while about
40% of the model clusters favor a faster shift to high pressure
and warmer temperatures.

&&

.AVIATION...07/0528Z.

At 0500Z at KLAX, the marine layer was around 2200 feet deep. The
top of the inversion was around 4200 feet at a temperature of 24
C.

High confidence in KWJF, KPMD, and KPRB TAFs.

Moderate confidence in remaining TAFs. There is a 30% chance of
VLIFR conditions at KSBP, KSMX, and KSBA through 15Z. For LA and
Ventura County coastal and valley sites, good confidence in
IFR/MVFR conditions. Clearing may occur +/- an hour of forecast
with a 25% chance of no clearing for KOXR and KSBA.

KLAX...Moderate confidence in TAF. Clearing may occur as late as
21Z. An east wind component is expected to remain below 5 kt.

KBUR...Moderate confidence in TAF. There is a 30% chance of IFR
conditions. Clearing may occur as late as 17Z.

&&

.MARINE...06/756 PM.

Moderate to high confidence (70 percent) in Small Craft Advisory
(SCA) level winds tonight through late Friday night, affecting
the waters south of Point Sal to San Nicolas Island. Winds may
subside some Friday morning, but are expected to increase again
Friday afternoon and evening over nearly the same location. Gusty,
near SCA level winds may briefly reach the waters north of Point
Sal Friday afternoon but as of now widespread SCA conditions are
not expected. Winds will fall below SCA levels Friday night, but
strengthen again Saturday afternoon/evening south of Point
Conception (40% chance of SCA level winds).

For the nearshore and coastal waters inside the southern
California bight, winds and seas are expected to remain below SCA
levels. There is a small (30 percent) chance of marginally gusty
SCA winds across the western portion of the Santa Barbara Channel
Friday evening.

Otherwise, a shallow marine layer depth over the coastal waters
will continue to bring a threat of dense fog. The highest chance
of dense fog will be for the waters from Point Sal and northward.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect until 3 AM PDT Friday for
      zones 673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Stewart/MW
AVIATION...Stewart
MARINE...Smith
SYNOPSIS...MW/Smith

weather.gov/losangeles

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