Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 04/30/22

Area Forecast Discussion

National Weather Service Los Angeles/Oxnard CA

 902 PM PDT Fri Apr 29 2022

.SYNOPSIS...29/709 PM.

Low clouds and fog will stay confined to the coastal areas on
Saturday morning. Stronger onshore flow will return Saturday
evening pushing low clouds further inland by Sunday morning. Above
normal temperatures on Saturday will return to normal by Sunday
morning.

&&

.SHORT TERM (FRI-MON)...29/859 PM.

Weak upper level ridge of high pressure over the region tonight,
will give way to a weak upper level trough passage over the area
on Saturday afternoon/evening. This will translate into stronger
onshore gradients between LAX-Daggett over the weekend, leading
to gusty onshore winds across the interior. Current satellite
imagery showing mostly clear skies across the forecast area this
evening. Latest ACARS data showing marine layer depth around
1500 feet across the LA basin this evening, down considerably
from earlier this morning. With a weak eddy circulation in place,
the highest probability of low clouds developing overnight into
Saturday morning will be across the LA basin, with a chance of
low clouds extending up to the Ventura county coast by morning.
The shallower marine layer will lead to some warming across the
interior with many valley and desert locations topping out in the
lower to mid 80s.

By Saturday night, the upper level trough passes through our
region, with increasing northwest flow aloft behind the system.
This will also tighten the northerly offshore pressure gradients
on Saturday night, especially across Santa Barbara county where
the Santa Barbara-Santa Maria pressure gradient is expected to
peak at -4.5 mb. This will likely result in advisory level wind
gusts of 35 to 50 mph on Saturday night across the western
portions of the Santa Barbara south coast and adjacent Santa Ynez
range. The focus of strongest winds will be near Gaviota and
Refugio.

*** From previous discussion ***

Looking at 5-10 degrees of cooling away from the coast Sunday,
thanks to the new airmass and strong onshore flow. Gusty northwest
winds persist for the Santa Barbara South Coast, and will develop
over spots along the I-5 Cooridor early Sunday. The current
forecast looks on track, with only minor adjustments to increase
the coverage of marine layer clouds Saturday night and Sunday
night.

.LONG TERM (TUE-FRI)...29/144 PM.

Onshore flow with marine layer clouds appears to the the dominant
feature in the extended period. The forecast shifts between
ridging Monday, a weak trough passage Tuesday, and ridging again
Wednesday. Thursday could see the strongest onshore flow with the
GFS deterministic model forecasting an LAX-DAG onshore gradient
near 11 mb. However, ensembles appear to struggle with strength of
the low system moving through Thursday so lower confidence in
what sort of winds will occur. There is also a non-zero chance of
precipitation starting Thursday night but as of now, no
significant accumulations are expected.

&&

.AVIATION...30/0008Z.

At 2355Z, the marine inversion at KLAX was based at 1500 feet.
The top of the inversion was 3700 feet with a temperature of 18
degrees Celsius.

Overall, moderate to high confidence in 00Z TAF package. For all
sites from Santa Barbara northward, as well as the deserts, high
confidence in VFR conditions through the TAF period. For the LAX
Basin sites, moderate confidence in current forecast due to
uncertainties in marine layer heights and timing. There is also
a 20 percent chance of IFR cigs reaching KOXR on Saturday morning.

KLAX...Overall, moderate confidence in 00Z TAF. Through this
evening, high confidence in VFR conditions. For tonight, moderate
confidence in return of MVFR CIGs, but low confidence in timing
(could be +/- 3 hours of current 12Z forecast). No significant
easterly wind component is expected.

KBUR...Overall, moderate to high confidence in 00Z TAF as VFR
conditions are expected through the TAF period. There is a 30%
chance of IFR/MVFR CIGs 12Z-16Z.

&&

.MARINE...29/831 PM.

For the Outer Waters, high confidence in Gale Warnings continuing
across zones 670/673 through at least Saturday night, with
gale warnings expanding to zone 676 by late Saturday
afternoon/night. For Sunday through Tuesday, high confidence in
Small Craft Advisory (SCA) level winds and seas with a 50-60%
chance of Gale force winds (especially across PZZ670/673). On
Wednesday, there is a 40% chance of SCA level winds across PZZ670.

For the Inner Waters north of Point Sal, moderate to high
confidence in current forecast. Tonight through Tuesday, high
confidence in SCA level winds, especially during the afternoon and
evening hours. There is a 30% chance of Gale force winds on
Saturday then again on Monday. On Wednesday, high confidence in
winds and seas remaining below SCA levels.

For the Inner Waters south of Point Conception, moderate to high
confidence in current forecast. For the western half of the Santa
Barbara Channel, there is a 70% chance of SCA level winds during
the afternoon and evening hours Saturday through Monday.
Otherwise, high confidence in winds and seas remaining below SCA
levels across the southern Inner Waters through Wednesday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect until 3 AM PDT Saturday for
      zone 645. (See LAXMWWLOX).
     Gale Warning in effect until 3 AM PDT Sunday for zones
      670-673. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 PM PDT Saturday for
      zone 676. (See LAXMWWLOX).
     Gale Warning in effect from 3 PM Saturday to 3 AM PDT Sunday
      for zone 676. (See LAXMWWLOX).

&&

$$

PUBLIC...Gomberg/Phillips
AVIATION...Gomberg
MARINE...Gomberg/RAT
SYNOPSIS...TF

weather.gov/losangeles

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