453
FXUS66 KLOX 071038
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
338 AM PDT Fri Jun 7 2024

.SYNOPSIS...07/337 AM.

Fairly widespread low clouds and nighttime fog will affect areas
near the coast each day into next week, with areas of partial
clearing during the afternoon. While temperatures will be a few to
several degrees below normal close to the coast with onshore
flow, temperatures will be warmer over interior sections.
Precipitation is not expected over the region through at least the
middle of next week.

&&

.SHORT TERM (TDY-SUN)...07/308 AM.

Upper level heights are expected to continue to fall gradually
over the next few days, with a moisture-starved trough reaching
the region by Sunday. However, the overall weather pattern will be
quite similar through the weekend, and dropping daytime high
temperatures will be the most notable difference day-to-day. For
interior locations (i.e., deserts, mountains, and most valleys),
temperatures will fall several degrees each day through the
weekend, bottoming out on Sunday with max temperatures below
normal by around 2 to 6 degrees. One exception will be Paso
Robles, which is likely to see another drastic 10+ degree drop in
temperatures today, as a cool southerly seabreeze will moderate
temperatures. Coastal areas will be much less affected by the
cooling airmass aloft. Strong onshore pressure gradients are
forecasted through the period. This will drive continued marine
layer clouds and strong sea breezes, which will keep temperatures
relatively constant at the coasts through the weekend (mid 60s to
low 70s).

The marine layer is currently around 1700 ft deep with a strong
inversion aloft, which is significant lifting by a Catalina Eddy
compared ydy evening. The lifting will make drizzle possible this
morning for LA and Ventura Counties. Low clouds are currently
creeping inland, and have reached the Santa Clarita Valley and
foothill locations. Clearing is expected to occur by the late
morning or early afternoon each day, except for beaches where
clouds are likely to persist all day. No major changes in cloud
cover through the weekend, except for slight deepening (further
inland extent) each day.

There is good agreement between the GFS and ECMWF that a cutoff
low will to set up to the southwest of SoCal Sunday night. This
cool low pressure system has the potential to disturb the warm
capping inversion and scattering out the marine layer. The more
likely scenario is that the system will lift the marine layer
which would result in overnight- to- morning drizzle.

The strong onshore pressure gradients will continue to drive
southwest winds across the Antelope Valley and foothills. Wind
gusts 30 to 40 mph will be common, and gusts up to 45 mph are
possible for the foothills. A Wind Advisory has been issued for
this afternoon into tonight for the western Antelope Valley
foothills, as the local enhancement for this zone may result in
advisory level wind gusts with little upper level support.

.LONG TERM (MON-THU)...07/338 AM.

Next week there is high model agreement that the dominant
synoptic feature will be a cut off low, that is likely to stall
to the southwest of the region before slowly traveling eastward.
The center of the low pressure system will pass either to the
south or directly over SoCal on Thursday or Friday. Overall
weather conditions will be fairly constant during the period. At
the surface, strong onshore pressure gradients are expected to
continue.

The marine layer pattern will be similar each day, as June Gloom
will prevail. Overnight and morning clouds will extend over coasts
and valleys and up to the foothills. Daytime clearing and
sunshine is likely by midday, except with strong onshore gradients
clouds may continue to cling to the beaches all day. High
temperatures will show dramatic differences from the coasts to the
deserts. Expect 60s to low 70s at the beaches, 70s to low 80s for
the valleys, and in the 90s in the Antelope Valley.

The cutoff low has the potential to lift the marine layer, thus
drizzle is possible each night into morning. During the afternoon,
instability brought about by the low pressure system may yield
cumulus cloud development over the mountains, but with little
mositure, showers are unlikely at this time. Towards the latter
part of the week, when the upper low has a chance of passing
directly over the region, there is a chance that the low pressure
will disturb the capping inversion and scatter out the marine
layer, leading to widespread clearing.

&&

.AVIATION...07/0630Z.

At 0515Z at KLAX, the marine layer was 1000 ft deep. The top of
the inversion was at 4500 ft with a temperature of 25 degrees C.

High confidence in TAFs for KWJF and KPMD

Moderate confidence for all other coastal and valley TAF sites.
There is a 20% chance for brief cigs at KPRB around 12Z. Vis
values will likely change frequently through 14Z. Flight Cat
changes may occur +/- 90 minutes from fcst time. Cig hgts may be
off by 200 ft.

KLAX...Moderate confidence in TAF. VIS will likely vary frequently
between 1SM AND 3SM. Vis in TAF will reflect SFC vis and not the
tall tower vis. There is a 30 percent chc of cigs remaining blo
010. No significant easterly wind component is expected.

KBUR...Moderate confidence in TAF. Low clouds could arrive as late
as 11Z. There is a 25 percent chc of 1/4SM VV002 conds 11Z-15Z.

&&

.MARINE...07/248 AM.

For the Outer Waters, moderate to high confidence in current
forecast. Tonight through Saturday morning, high confidence in
winds and seas remaining below Small Craft Advisory (SCA) levels.
From Saturday afternoon through Sunday night, there is a 50-60%
chance of SCA level winds. For Monday and Tuesday, high confidence
in winds and seas remaining below SCA levels.

For the Inner Waters north of Point Sal, moderate to high
confidence in current forecast. Today through Saturday, high
confidence in winds and seas remaining below SCA levels. For
Sunday, there is a 30-40% chance of SCA level winds in the
afternoon and evening hours. On Monday and Tuesday, high
confidence in winds and seas remaining below SCA levels.

For the Inner Waters south of Point Conception, high confidence
in current forecast. Today through Tuesday, winds and seas are
expected to remain below SCA levels.

Through the weekend, dense fog, with visibility of one mile or
less, will continue to impact the coastal waters north of Point
Conception during the night and morning hours.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect from 3 PM this afternoon to 3 AM PDT
      Saturday for zone 381. (See LAXNPWLOX).
     Heat Advisory remains in effect until 8 PM PDT this evening
      for zones 382-383. (See LAXNPWLOX).
PZ...NONE.

&&

$$

PUBLIC...Schoenfeld/Rorke
AVIATION...Rorke
MARINE...RAT/Phillips/ASR
SYNOPSIS...Cohen/RS

weather.gov/losangeles

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