FXUS66 KLOX 062055

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

.SYNOPSIS...06/948 AM.

High pressure aloft over northern California will bring a warming
trend 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 (TDY-SUN)...06/132 PM.

The upper low that was over southern AZ has moved west to the
northern part of the Gulf of California. This was partly to blame
for the increased marine layer depth across the southern part of
the forecast area while the Central Coast had another morning of
dense fog and low cloud bases. Onshore gradients continue to
decrease but low clouds are not moving far offshore and are poised
to move in quickly this evening.

By Friday morning offshore gradient trends and some warming of
the lower levels should lead to a reduction of the marine layer
depth and less inland penetration of the low clouds, followed by a
warming trend most areas of 3-6 degrees. Then not a lot of change
over the weekend. 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.



At 1717Z, the marine layer was around 1700 feet deep at KLAX. The
top of the inversion was near 2700 feet with a temperature around
25 degrees Celsius.

High confidence in the current forecast for desert terminals.
Low-to-moderate confidence in the current forecast for coastal and
valley terminals. Given current satellite imagery, clouds are
expected to clear from most sites, however, there is a 30% chance
cigs will fail to clear from KOXR and KLAX. An early return of
IFR to MVFR conditions should be expected, possibly spreading back
into immediate coastal terminals between 23Z and 04Z.

KLAX...MVFR conditions will persist through at least 18Z. There
is a 30 percent chance that MVFR conditions may linger through
through the day, with a higher chance of clearing delayed as late
as 20Z. East wind component is expected to remain below 6 kt
through the period.

KBUR...Moderate confidence in 00Z TAF, with some lingering lower
visibilities this morning. Expecting an early return of cigs, with
lower confidence in arrival and clearing times of cigs.


.MARINE...06/137 PM.

Moderate to high confidence (70 percent) in Small Craft Advisory
(SCA) level winds this afternoon and tonight, primarily affecting
the waters south of Point Sal to San Nicolas Island. There is
moderate (50-60 percent) chance of another round of SCA level
winds on 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 (50% 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
this evening and Friday evening, and a slight chance (10 percent)
Saturday 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.


PZ...Small Craft Advisory in effect until 3 AM PDT Friday for
      zones 673-676. (See LAXMWWLOX).





Experimental Graphical Hazardous Weather Outlook at:

Chino Hills, Ca. Weather | www.ChinoHillsWeather.com