Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 06/24/22

Area Forecast Discussion

National Weather Service Los Angeles/Oxnard CA

 853 PM PDT Thu Jun 23 2022

.SYNOPSIS...23/728 PM.

Mostly clear skies with night through morning coastal low clouds
and patchy dense fog are expected tonight through at least the
weekend. Continued inland heat is expected during the period, with
slightly cooler temperatures at the coast.

&&

.SHORT TERM (THU-SUN)...23/802 PM.

***UPDATE***

Overall, a very quiet early evening across the forecast district.
Latest satellite and surface observations indicate some stratus
across the coastal waters and immediate coast with some lingering
cumulus over the higher terrain. Current AMDAR soundings indicate
marine inversion near 800 feet deep. No significant winds are
observed.

Forecast-wise, no significant issues in the immediate short term.
With sunset, any lingering cumulus buildups will dissipate. So,
overnight, the only clouds of concern will be the marine layer
stratus and fog. Do not expect the inversion to deepen overnight,
so any stratus should only be an issue for the coastal plain.
Given the shallow nature of the inversion, there could be some
patchy dense fog overnight. Night shift will need to watch this
situation, just in case the dense fog becomes more widespread.
Other than the stratus/fog, there should not be any significant
issues overnight.

Current forecast has good handle on the immediate short term. So,
other than minor tweaks to the sky/weather grids, no significant
updates are anticipated.

***From Previous Discussion***

Temperatures today should be less variable with much less shower
activity expected. The low system that drove our convection
yesterday will start lifting east, but a chance of thunderstorms
remains from the Ventura and LA County Mountains to the Antelope
Valley today. The NAM model favors development over the eastern
San Gabriel Mountains that progresses into the Antelope Valley.
Moderate LI and K-index values support convection, with plenty of
MUCAPE available (1400 to 2200 J/kg). PWAT values are limited
however, and are expected to decrease through the afternoon.
Current radar reflectivity shows isolated storms up in Kern
County, very closely aligned with a bullseye of high vorticity
advection. It`s possible that we are too far south for upper
level forcing to trigger convection, but will leave chances in the
forecast until 5PM in case something develops.

The current pattern is rather quite the next few days as the weak
low pushes off to the east. Heights gradually rise, further
compacting the already shallow marine layer. Thus, expecting
recurring night to morning dense fog over the coastal waters to
affect the coasts and valleys tonight through Sunday night/Monday
morning. Cooler temperatures are expected for the coasts, with
hot, dry conditions over interior areas. Rising heights should
also lead to gradual warming of already hot temperatures over the
mountains and deserts from Friday into Sunday. Heat in the valleys
will be a tricker forecast, but values may need to be increased
Saturday, with guidance showing the potential for hot spots to
reach 100 degrees. The most significant heat should occur Sunday,
as winds could become briefly offshore and heights begin peaking
near 591 DM. Therefore, heat advisories may be needed for the
mountain areas.

Flow remains rather weak so not expecting too many wind issues
over the next few days. However, the LAX-DAG onshore gradient is
trending a little stronger in the afternoon so west winds will
become breezy for the Antelope Valley and interior SLO County each
afternoon through Sunday. The SBA-SMX offshore gradient starts to
approach -2 mb, indicating Sundowner winds Saturday night, with a
better chance for advisory level north winds Sunday night along
western portions of the Santa Barbara south coast.

.LONG TERM (MON-THU)...23/240 PM.

The EC and GFS deterministic and especially mean ensembles are in
generally good agreement in the extended period.

The main concerns in the long range will be hot, dry weather and
winds. Morning LAX-DAG pressure gradients Monday indicate very
weak to light offshore flow, and heights continue to rise to
591-593 DM over the Antelope Valley. Guidance suggests the
potential to reach the mid to upper 100s over the interior and the
mid 90s to low 100s for the mountains. Heat advisories may be
required for the mountains on Monday. Heights rise gradually and
level off early next week, supporting continued heat. However,
there is a trade off between rising heights and increasing onshore
flow that will moderate temperatures for the coasts/valleys.

The Antelope Valley may start reaching advisory level winds
Tuesday to Thursday, with onshore flow peaks around Wednesday
afternoon, thanks to an LAX-DAG gradient potentially reaching 7-8
mb. Could also see a continuation of sundowner winds through the
extended period. Also expecting continued marine layer clouds with
a shallow marine layer and the potential for dense fog along the
coasts.

&&

.AVIATION...24/0352Z.

At 0350Z, the marine inversion at KLAX was based at 800 feet.
The top of the inversion was 2000 feet with a temperature
of 28 degrees Celsius.

Low to moderate confidence in 06Z coastal TAFs and high
confidence in valley/desert TAFs. Lower confidence for coastal
sites is due to the uncertainties of the development of marine
layer stratus and associated flight categories.

KLAX...Low to moderate confidence in 06Z TAF. Moderate confidence
in CAVU conditions through this evening. Overnight, moderate
confidence in return of CIG/VSBY restrictions, but low confidence
in timing (could be +/- 4 hours of current 10Z forecast) and
flight category (could range from IFR to VLIFR). No significant
easterly wind component is expected.

KBUR...High confidence in 06Z TAF as CAVU conditions are
anticipate through the period.

&&

.MARINE...23/759 PM.

For the Outer Waters, moderate to high confidence in current
forecast. Good confidence in winds and seas remaining below Small
Craft Advisory (SCA) levels tonight through Friday. However, there
is a 30% chance of SCA level winds around Point Conception this
evening. For Saturday and Sunday, there is a 30% chance of SCA
level winds, especially south of Point Conception (Zones
PZZ673/676). For Monday and Tuesday there is a 50-60 percent
chance of SCA winds over all of the outer waters.

For the Inner Waters north of Point Conception, high confidence
in current forecast as winds and seas are expected to remain
below SCA levels tonight through Sunday, with winds gradually
increasing to SCA levels Monday into Tuesday.

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

A 19 second period south swell of 2 to locally 4 feet is expected
to build into the waters early next week from Tropical Cyclone
Celia, likely peaking Tuesday afternoon through early Wednesday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.

&&

$$

PUBLIC...Phillips/Thompson
AVIATION...RAT
MARINE...Smith
SYNOPSIS...Smith

weather.gov/losangeles

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