Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 04/10/23

Area Forecast Discussion

National Weather Service Los Angeles/Oxnard CA

 853 PM PDT Sun Apr 9 2023

.SYNOPSIS...09/337 PM.

Warmer temperatures are expected to persist through Monday, then a
cooling trend will begin on Tuesday as high pressure moves east
of the area. Further cooling is expected later in the week as a
cold low pressure system moves over the region. This cold low
will bring gusty winds to the coastal waters and a chance of
showers to Los Angeles county on Thursday.

&&

.SHORT TERM (SUN-WED)...09/850 PM.

Upper level ridge of high pressure peaked over the region today,
bringing a warming and drying trend across the interior.
Temperatures climbed into the 80s across the valleys and
deserts. Current satellite imagery showed low clouds and
fog streaming into coastal areas this evening. ACARS data
showing the marine layer depth around 600 feet across the
LA Basin. With such a strong and low inversion in place,
dense fog will be likely across much of the coastal areas
in Los Angeles, Ventura, and Santa Barbara counties where
a dense fog advisory is in effect later this evening through
Monday morning. Another warm day is expected on Monday, with
highs well into the 80s.

*** Update from previous discussion ***

The next low pressure system continues to look on the dry side,
with the first trough associated with the low off the British
Columbia coast passing over the region Tuesday. Gusty northwest
winds develop over the coastal waters, near Point Conception, and
for the I-5 Corridor into the Antelope Valley foothills Tuesday
afternoon. Winds will generally be below advisory levels, however
gusts will approach 45 mph along western portions of the Santa
Ynez range by Tuesday night. Temperatures trend 5 to 10 degrees
colder on Tuesday with stronger onshore flow and falling heights.
Ensemble guidance along with the NAM model suggests a slight
chance (less than 10%) for light rain over unsloped areas in
Ventura and Los Angeles County Tuesday night. Lower confidence in
this so will keep an eye on this to see if guidance still supports
it for the next shift.

.LONG TERM (THU-SUN)...09/246 PM.

The GFS and EC deterministic mdls remain in agreement in a frontal
passage Wednesday night, bringing stronger northerly flow to the
region. Ensembles agree on light rain and mountain snow over Los
Angeles and Ventura County with the main frontal passage. Marine
layer clouds could hang onto the coasts south of Point Conception
Wednesday, but by Thursday the cold air advection will likely
clear out the region. The cooling trend continues through
Thursday, with high temperatures falling to the 50s and 60s.
Temperatures start to rebound Saturday as another ridge builds in.

&&

.AVIATION...09/2357Z.

At 2350Z at KLAX, the marine layer was 800 ft deep with an
inversion top at 2500 ft and temperature of 20 C.

Onshore flow combined with a lowering marine layer inversion
kept low clouds and fog along the immediate coastal areas south
of Point Conception this afternoon, with an expected quick surge
into KSBA, KOXR, KCMA, KSMO, KLAX, and KLGB this afternoon and
evening. Expect a very similar low cloud pattern tonight with
widespread LIFR to VLIFR conditions due to a similarly shallow
marine layer, except there is a 40 percent chance that low clouds
will not make it into the LA valleys.

KLAX...Moderate confidence in 00Z TAF. LIFR cigs have returned to
KLAX late this afternoon and are expected to continue through
Monday morning. There is a 20 percent chance of VLIFR conditions
late tonight into early Monday morning.

KBUR...Moderate confidence in 00Z TAF. There is a 40 percent
chance that cigs will not reach KBUR late tonight into early
Monday morning.

&&

.MARINE...09/830 PM.

In the outer waters, winds and seas are below SCA levels. However,
winds will be at least SCA levels Mon evening thru Thu, with a
50% chance of gale force winds Tue thru Wed.

Across the inner waters north of Pt. Conception, there is a 40%
chance of SCA conds Mon evening. SCA conds will continue to be
likely during the afternoon thru late evening hours Tue thru Thu,
and there is a 30% chance of Gale force winds during the
afternoon/evening hours Tue and Wed.

In the SBA Channel, conds are expected to remain below SCA levels
thru Tue morning. SCA conds are likely late Tue afternoon into
Tue night, especially across western sections, and during the
afternoon thru late night hours Wed and Thu.

Across the southern inner waters, conds are expected to remain
below SCA levels thru Wed morning, then SCA conds are likely much
of the time Wed afternoon thru Thu.

The strong wind during mid week will generate large and steep
seas everywhere, with short periods and ample white-capping.

Widespread dense fog will affect the coastal waters with
visibilities of 1 nm or less tonight into Monday morning.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Dense Fog Advisory in effect until 11 AM PDT Monday for zones
      346>350-354-355-362-366>368. (See LAXNPWLOX).
PZ...NONE.

&&

$$

PUBLIC...Gomberg/Phillips
AVIATION...Gomberg
MARINE...Smith
SYNOPSIS...Phillips/Smith

weather.gov/losangeles

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