Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 05/04/22

Area Forecast Discussion

National Weather Service Los Angeles/Oxnard CA

 813 PM PDT Tue May 3 2022

.SYNOPSIS...03/1158 AM.

Patchy low clouds and fog will return to many beaches through
Wednesday morning, then warmer weather is expected to continue
through the rest of the week. Temperatures will trend downward for
the upcoming weekend with breezy onshore winds each afternoon.

&&

.SHORT TERM (TUE-FRI)...03/812 PM.

58***UPDATE***

Overall, a very quiet evening across the forecast district. Latest
satellite and surface observations indicate clear skies for all
areas. Current AMDAR soundings indicate marine inversion around
1600 feet deep. As for winds, just seeing some early evening gusts
in the 15-25 MPH range.

For the immediate short term, main focus will be on the marine
layer stratus and winds. Overnight, a decent marine inversion
should remain in place. However at the same time, weak northeast
flow will be developing overnight. So, expect some stratus to
develop along the coast, but confidence is moderate at best, due
to the offshore flow. Any stratus that develops should be confined
to the coastal plain of Ventura/LA counties. As for the winds,
offshore gradients will only be weak overnight and upper level
support is limited. So, expect any northeasterly winds to remain
below advisory levels with the marine inversion likely preventing
any winds from surfacing across the immediate coast.

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

***From Previous Discussion***

It took longer than expected, but clouds finally scattered out
shortly after lunch for the majority of the coastal areas. The
boundary layer remains fairly moist though south of Pt Conception
with a stubborn marine layer up to 3500 feet, which has hardly
budged since 12Z.

Pressure gradients are trending offshore and northerly winds were
rather light in the mountains. Model data continues to indicate
northeast winds becoming stronger across Ventura and Los Angeles
Counties toward morning and at least light offshore winds will
reach within a couple of miles of the ocean. However, expect low
clouds and patchy fog to return in a similar fashion tonight from
Santa Barbara southward, along with areas of dense fog in the
Santa Ynez Valley by sunrise. The offshore winds will be brief and
rather insignificant Wednesday, but enough to bring much warmer
air down into the valleys and inland coastal areas with highs of
82 to 92 degrees. The winds do turn back onshore in the afternoon
with cooling at the coasts, where it will more difficult to reach
80 degrees.

High pressure builds over the southwest California through
Thursday then becomes very broad across all of the desert
Southwest through Friday. Heights do build to 582-585dm, however,
the onshore pressure gradients strengthen to 8 or 9mb during that
time. Expect temperatures to remain pleasant at the coast with
bouts of night and morning low clouds, with continued warm
conditions of 80-90 degrees across interior valleys. Gusty
southwest winds will be likely through the highway 14 corridor to
the Antelope Valley foothills, especially Thursday and Friday
afternoons. Sundowners will make a return across the western Santa
Ynez Range by Thursday night.

.LONG TERM (SAT-TUE)...03/1242 PM.

For the longer range will be relying heavily on the ensemble
suites that start out showing very good mean 500mb anomaly consistency
in a cold low pressure trough entering the Pacific Northwest and
northern Great Basin by Sunday. This trough will have reinforcing
cold air associated with it for a much cooler, breezy week ahead
with a large scale trough remaining over much of the West through
at least next Wednesday. The details get a little muddier with the
amount of cooling and any potential moisture this far south,
however, several ECM ensemble members in recent model runs have
held onto a few hundredths of precipitation over the area early
next week. The deterministic ECM looks a little more baggy with
the trough over CA compared to other models, therefore, a better
potential for moisture. The NBM data only puts in a 10 percent
chance of any precipitation next Monday and the uncertainty is
great enough to leave this as the official forecast for now.

The main impact will be gusty west-northwest winds for many areas
including the coastal waters late Saturday through the early part
of next week. The other impact will be the colder than normal
temperatures starting Sunday and continuing through Wednesday.

&&

.AVIATION...04/0312Z.

At 0310Z, the marine inversion at KLAX was based at 1900 feet.
The top of the inversion was 4100 feet with a temperature of
19 degrees Celsius.

Overall, high confidence in 06Z TAFs north of Point Conception as
well as the deserts. Low to moderate confidence for coastal and
valley sites south of Point Conception. Lower confidence due to
the uncertainty of the marine layer stratus developing overnight.

KLAX...Overall, moderate confidence in 06Z TAF. High confidence
in CAVU conditions through this evening. For tonight, moderate
confidence in return of MVFR CIGs, but low confidence in potential
timing of return (could be +/- 3 hours of current 12Z forecast).
No significant easterly wind component is expected.

KBUR...Overall, moderate confidence in 06Z TAF. High confidence
in CAVU conditions through this evening. Overnight, there is a 30%
chance of MVFR CIGs 12Z-16Z.

&&

.MARINE...03/812 PM.

For the Outer Waters, moderate to high confidence in current
forecast. High confidence in Small Craft Advisory (SCA) level
winds through tonight then conditions dropping below SCA levels
Wednesday and Wednesday night. From Thursday through Sunday, high
confidence in SCA level winds and seas. Additionally, there is a
50% chance of widespread gale force winds Friday night through
Sunday.

For the Inner Waters north of Point Sal, moderate to high
confidence in current forecast. High confidence in SCA level winds
tonight then conditions dropping below SCA levels Wednesday and
Wednesday night. For Thursday through Sunday, high confidence in
SCA level winds. Additionally, there is a 30% chance of gale force
winds Saturday and Sunday.

For the Inner Waters south of Point Conception, moderate to high
confidence in current forecast. Tonight through Thursday night,
generally high confidence in winds/seas remaining below SCA levels
although there is a 30% chance of SCA level winds Thursday evening
across the western half of the Santa Barbara Channel. For Friday
through Sunday, high confidence in SCA level winds developing
across western sections on Friday then spreading across the entire
southern Inner Waters Saturday and Sunday. Additionally, there is
a 30% chance of Gale force winds Saturday and Sunday.

&&

.BEACHES...03/1251 PM.

A long-period southerly swell and an increase in northwest swell
could bring high surf conditions with hazardous rip currents to
the central coast as early as Thursday, and to beaches south of
Point Conception by Sunday. Also, locally generated short period
swells may develop this weekend, potentially increasing beach
hazards for many coastal areas.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect until 3 AM PDT Wednesday for
      zones 645-670-673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...EB/RAT
AVIATION...RAT
MARINE...RAT
BEACHES...Sweet/Munroe
SYNOPSIS...EB

weather.gov/losangeles

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