Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 08/27/22

Area Forecast Discussion

National Weather Service Los Angeles/Oxnard CA

 818 PM PDT Fri Aug 26 2022

.SYNOPSIS...26/653 PM.

An upper low moving across northern California will bring a
cooling trend to the area through this weekend, with temperatures
dropping below normal. Another significant warming trend is
expected by the middle of next week.

&&

.SHORT TERM (FRI-MON)...26/817 PM.

***UPDATE***

Latest satellite/surface observations indicate stratus/fog
beginning to establish across the coastal plain with clear skies
elsewhere. Current AMDAR soundings indicate marine inversion near
1200 feet deep.

Forecast-wise for the immediate short term, only issue will be the
extent of the marine layer stratus. With continued onshore
gradients, stratus/fog should become widespread across the coastal
plain overnight. With inversion slightly deeper than last night,
any dense fog should be more localized overnight. Do not
anticipate much penetration into the coastal valleys overnight,
based on HREF forecast. Other than any coastal stratus/fog, skies
will remain clear overnight.

Overall, current forecast has good handle on the immediate short
term. So, no significant updates are expected.

***From Previous Discussion***

A quiet few days of weather going into the weekend as a weak low
pressure system moves in the Pac NW. This has already initiated a
cooling trend across the area which will continue through Sunday.
Onshore flow has increased by about 1mb since yesterday and this
also expected to continue. Temperatures are expected to fall to
5-10 degrees below normal in most areas except the far interior
where temps will be near normal. A deepening marine layer will
result in less fog over the coast but also allow low clouds to
push into the valleys as early as Saturday morning and likely even
farther inland Sunday morning. Southwest flow aloft around the
trough to the north will push all monsoon moisture and instability
well to the east so no thunderstorms are expected.

We`ll likely start to turn the corner towards warming Monday as
most model solutions show the upper low lifting out and high
pressure building in from the southeast. The GFS deterministic
model is slower on this transition and thus a little cooler than
the ensemble mean which are favors a faster recovery.

.LONG TERM (TUE-FRI)...26/202 PM.

Ensembles continue to strongly favor a significant warming trend
next week, starting Tuesday and likely peaking Wed/Thu as a 595dam
high pushes over southern California. In addition, onshore flow
will be weakening during that time, limiting the typical seabreeze
cooling effect and allowing at least some of that warming to
reach the coast. Highs expected to climb well into the 90s and
as high as 105 in the coastal valleys and possibly close to 110 in
the Antelope Valley during the hottest days. Coastal areas will be
cooler but still mid 80s to lower 90s likely away from the
immediate coast. There`s a good chance that heat advisories and
possibly even warnings will be needed next week, potentially
including some coastal areas as well depending on how the pressure
gradients respond.

&&

.AVIATION...26/2315Z.

At 2230Z, the marine inversion at KLAX was based at 1100 feet.
The top of the inversion was 3200 feet with a temperature of
27 degrees Celsius.

Overall, low to moderate confidence in 00Z coastal TAFs and
moderate to high confidence in valley/desert TAFs. Lower
confidence for coastal sites due to uncertainty with the behavior
of the marine layer stratus. Low confidence in timing of arrival,
dissipation and category changes of CIG/VSBY restrictions. For
valley and desert TAFs, there is a 20% chance of LIFR/VLIFR at
KPRB and KBUR overnight, but high confidence in CAVU conditions
for other interior sites.

KLAX...Overall, moderate confidence in 00Z TAF. High confidence in
CIG/VSBY restrictions through Saturday morning, but moderate
confidence in flight category (there is a 30% chance of LIFR
conditions overnight) and disspiation (could be +/- 2 hours of
current 18Z forecast). No significant easterly wind component is
expected.

KBUR...High confidence in 00Z TAF. There is a 15-20% chance of
IFR/LIFR conditions 11Z-16Z.

&&

.MARINE...26/815 PM.

Moderate confidence in current forecast, with the SCA over the
waters from Point Conception to San Nicolas Island extended
through 3 AM Saturday. While the winds may diminish by around
midnight, the seas are currently up to 7 feet at 8 seconds, and
this is likely to persist into the early morning hours. For the
Santa Barbara Channel, believe that gusts will likely be near or
below 20 knots, with a few localized gusts to 25 knots possible
over the far western portions. Otherwise, high confidence that the
remainder of the waters will remain below SCA levels tonight
and into Saturday morning.

A return of more widespread, potentially SCA level NW winds from
the waters west of Point Sal to San Nicolas Island is likely
Saturday afternoon and evening, and possible Sunday and Monday
during the afternoon and evening period.

Patchy dense fog is likely over much of the waters tonight into
early Saturday as a shallow marine layer remains in place.

&&

.BEACHES...26/135 PM.

An elevated southerly swell will approach the beaches this
weekend, creating 3 to 6 foot breakers, mainly on south facing
beaches. There will also be an increased threat of strong rip
currents, creating hazardous swimming conditions at affected
beaches. Please see the product LAXCFWLOX for more details.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement in effect from 6 AM PDT Saturday
      through Sunday afternoon for zones 87-354-363-364. (See LAXCFWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT Saturday for
      zones 673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...MW/Thompson
AVIATION...RAT
MARINE...Smith
BEACHES...Sweet
SYNOPSIS...MW/Smith

weather.gov/losangeles

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