-- Discussion containing changed information from previous version are highlighted. --
937
FXUS66 KLOX 011800 AAA
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
1100 AM PDT Sat Jun 1 2024

.SYNOPSIS...01/953 AM.

A persistent marine layer with cooler than normal weather will
remain in place through the weekend as strong onshore flow
continues across the area. High pressure aloft will build in next
week, weaken onshore flow, and bring a warming trend to area. The
hottest temperatures are expected for the interior portions of
the area Tuesday through Thursday.

&&

.SHORT TERM (TDY-MON)...01/958 AM.

***UPDATE***

Marine layer depth back up to 3500 feet this morning across the LA
Basin, sloping down to around 1500 feet north of Pt Conception.
Across southern areas clouds have pushed back up the coastal
slopes and all the way to Acton. Drizzle was persistent enough to
create measurable rain across portions of Ventura and southern
Santa Barbara Counties. Gradients are almost 3mb stronger than
yesterday at this time. All this points to a very slow (if any)
clearing day across coast/valleys, especially south of Pt
Conception, with temperatures 4-8 degrees below normal.

***From Previous Discussion***

A cooler than normal weather pattern is expected to persist
through the weekend as strong onshore flow will remain in place.
The forecast remains near persistence along the coast while
continuing a cooling trend across the interior portions of the
area. Low clouds will likely struggle to clear again today, but
there is a moderate chance that southern Santa Barbara County and
the Ventura County coast could break out of the low clouds this
evening as a northerly surface pressure gradient develops.
Statistics favor portions of the area breaking out of the clouds
late this afternoon and evening, but May Gray has had its grip on
the region with the month of May finishing out cooler than normal.
June is shaping up to start similarly.

Strong onshore pressure gradients will develop gusty onshore winds
in the Antelope Valley and adjacent foothill areas this afternoon
and evening. The latest forecast guidance puts KPMD and KWJF in
the range of advisory outcomes, and a wind advisory was added from
noon today to 9 pm. Certainly, the strongest winds will be
expected in wind-favored locations, such as Lake Palmdale and
Sierra Pelona.

A wind advisory was also added for southwestern Santa Barbara
County tonight as the trough passing by will bring a tightening
northerly pressure gradient. Gusty Sundowner winds will develop
tonight, strongest west of Goleta out toward Gaviota and Refugio
State beaches in the evening. As the northerly pressure gradient
will remain in place for Sunday night and again Monday night, wind
advisories may be needed again the next several nights, possibly
spreading east into the southeastern portion on Monday night. EPS
ensemble members continue to suggest advisory level winds
developing for KSDB on Monday night and into Tuesday morning.

With the trough passing by, high pressure aloft will build into
the region on Monday. A warming trend will establish and the
region will start to heat up.

.LONG TERM (TUE-FRI)...01/444 AM.

The warming trend will turn more significant away from the coast
across the interior portions Tuesday through Thursday. Broad
troughing over the region will dig south of the border and carve
out a cutoff low into the middle to late next week. An upper-level
ridge will nose into southeast California. The air mass will heat
up away from the coast. The latest NBM solutions suggest an 80 to
90 percent chance of KPMD and KWJF hitting the 100 degree mark by
Wednesday. As well, there are low-to-moderate chances of 100
degree days on Tuesday and Thursday with chances climbing for
later in the week over the previous runs. Closer to the coast, the
marine layer depth will shrink some, but strong onshore flow is
progged to remain in place. Thus, night through morning low clouds
and fog will likely remain a staple of the forecast for the
coastal and valley areas through the period. The beaches and
immediate coastal areas could remain shrouded in clouds into late
next week at times.

While not definite, there is an outside chance that given the
southeast flow aloft, an early start to the southern California
Desert Monsoon Season could begin early. EPS solutions highlight a
5-10 percent chance of precipitation at KGXA, KPMD, and KSDB and
pattern recognition of the deterministic GFS solutions suggest a
pattern consistent with such an outcome. For now, the forecast
goes with NBM values, but there is a non-zero chance for late next
week of afternoon and evening showers and thunderstorms.

&&

.AVIATION...
-- Changed Discussion --
01/1759Z.

At 1715Z at KLAX, the marine layer was 2600 ft deep. The top of
the inversion was at 4300 feet with a temperature of 20 deg C.

Moderate to hi confidence in the 18Z TAFs. Low clouds with
IFR/MVFR cigs over the coast and adjacent vlys will clear to near
the coast by early this afternoon, except MVFR conds are likely
to persist thru the afternoon at KOXR and KLAX and possibly KSMO.
IFR/MVFR cigs will likely spread back inland tonight and affect
all coast and adjacent vly airfields including KPRB and continue
into late Sun morning. The timing of the dissipation and onset of
low clouds may be off +/- an hour or two, with the largest
uncertainty of the onset of low clouds tonight for KBUR, KVNY and
KSBA.

For KWJF and KPMD, there is hi confidence VFR conds will continue
thru the TAF period. Gusty SW winds will affect these airfields
for most of the fcst period.

KLAX...Moderate to hi confidence in the 18Z TAF. MVFR cigs will
likely persist this afternoon with only a 20% chance of the low
clouds scattering out. MVFR cigs will continue tonight thru Sun
afternoon. There is a 20% chance of an east wind of 7-8 kt 10Z-16Z
Sun.

KBUR...Moderate confidence in the 18Z TAF. MVFR cigs are expected
until about 20Z then VFR conds will prevail into this evening.
IFR cigs should move back in by 07Z this evening before improving
to MVFR by 17Z Sun. The timing of the dissipation and onset of
the low clouds and changes in flight cats may be off +/- an hour
or two.
-- End Changed Discussion --

&&

.MARINE...01/840 AM.

In the northern outer waters zone (PZZ670), SCA winds will likely
to increase to Gale Force (70% chance) this afternoon and
continue thru late tonight. Then, SCA conds are expected (80%
chance) late tonight thru Tue. There is a 40% chance gales Sun
afternoon/eve. There is a 50% chance of SCA conds Tue night/Wed.

In the southern two outer waters zones, (PZZ673/676), SCA conds
are likely this afternoon (70-80% chance), continuing thru late
Mon night or Tue. There is a 30% chance of gales this eve and
again Sun afternoon/eve from Pt Conception to San Nicolas Island.

In the inner waters N of Pt. Sal, SCA level winds are likely (70%
chance) during the afternoon/eve hours today thru Mon. There is a
40% chance that SCA level conds will continue during the night
thru morning hours thru Mon.

In the inner waters S of Pt. Sal, there is a 60% chance of SCA
winds in western portion of the SBA Channel during the afternoon
and evening hours today and Sun, with a 30% chance Mon. Otherwise,
conds over the inner waters should be below SCA levels thru Wed.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect from 5 PM this afternoon to 3 AM PDT
      Sunday for zones 349-351. (See LAXNPWLOX).
     Wind Advisory in effect until 9 PM PDT this evening for zones
      381-383. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect from 2 PM this afternoon to 9
      PM PDT this evening for zones 645-650. (See LAXMWWLOX).
     Small Craft Advisory in effect until 2 PM PDT this afternoon
      for zone 670. (See LAXMWWLOX).
     Gale Warning in effect from 2 PM this afternoon to 3 AM PDT
      Sunday for zone 670. (See LAXMWWLOX).
     Small Craft Advisory in effect from 2 PM this afternoon to 3
      AM PDT Tuesday for zones 673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...MW/Hall
AVIATION...Sirard
MARINE...DB/Sirard
SYNOPSIS...Hall

weather.gov/losangeles

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