-- Discussion containing changed information from previous version are highlighted. --
496
FXUS66 KLOX 211836
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
1136 AM PDT Tue May 21 2024

.SYNOPSIS...21/231 AM.

Low clouds will continue through the morning with better clearing
this afternoon. More sunshine with slight warming is expected
today and Wednesday as onshore flow weakens. Then cooler with
increasing marine layer clouds again the latter half of next week.

&&

.SHORT TERM (TDY-THU)...21/828 AM.

***UPDATE***

Offshore trends and a deep marine layer has lead to a chaotic
low cloud pattern across southern areas with low confidence
overall in cloud trends through tonight. Have updated the forecast
with the latest thinking, although there is a 30-50 percent
chance that low clouds are delayed to reform tonight and with
skies potentially remaining clear for some coastal areas with
the Santa Barbara South Coast and western Ventura County most
likely to remain clear.

***From Previous Discussion***

Broad scale pos tilt troffing will cover the state and most of the
western CONUS through the next three days. Good offshore trends
will make today the day with the weakest onshore flow. Onshore
flow will increase both Wed and Thu esp in the W to E direction.

Today will likely be the sunniest day due to the weaker onshore
flow and a very weak marine layer capping inversion. Decent N to S
flow across SBA county will keep the south coast cloud free. It
is likely that most of the area will see sunshine in the afternoon
and the evening will also likely be clear for most of the air.
Rising hgts, extra sunshine and weaker seabreezes will all add up
to a noticeably warmer day (4 to 8 locally 10 degrees). Despite
this warming max temps will come in 4 to 8 degrees blo normal.

Clouds will be slower to form tonight but by dawn most of the
coasts and vlys should be covered with stratus. Clearing will
likely be a little slower but almost all of the area will see
sunshine in the afternoon. Higher hgts will bring continued
warming to the interior but the stronger seabreeze will cool the
coasts and to a lesser degree the vlys.

The troffing will be a little more vigorous on Thursday and the
onshore flow will increase to near 9 mb w to e. Look for the
return of a deep vly penetrating marine layer stratus field with
slow to no clearing. Max temps will fall 3 to 6 degrees and will
end up mostly in the mid 60s to lower 70s across the coasts and
vlys. The interior will end up upper 70s and to mid 80s.

.LONG TERM (FRI-MON)...21/317 AM.

For the extended, models and their respective ensembles are in
decent agreement through the period. The broad upper level trof
will continue over the area Fri/Sat. On Sun/Mon weak ridge will
move into the state.

On Fri/Sat look for a May Grey pattern with total marine layer
stratus coverage over the csts/vly and xtnding into the mtn
passes. Clearing will be slow across the vlys and interior coastal
sections while most of the coastlines will remain mired in the low
clouds. The moderate to strong onshore gradients will likely
produce some advisory level westerly winds across interior
sections each afternoon and early evening, especially in the
Antelope Valley foothills.

For Sunday/Monday, increasing heights will smoosh the marine
layer down which will decrease the inland penetration. Also with
rising thicknesses and less marine influence, a warming trend can
be expected for all areas except right at the beaches.

&&

.AVIATION...
-- Changed Discussion --
21/1835Z.

At 18z at KLAX, the marine layer was 3300 ft deep. The top of the
inversion was at 4000 feet with a temperature of 15 C.

High confidence in KPMD, KWJF, KPRB.

Generally high confidence elsewhere through 03Z, with low
confidence after 06Z, due to uncertainty in timing and coverage of
low cigs. Timing of cigs may be off by 3 hours with a 30% chance
that VFR conditions prevail for KBUR, KVNY, KCMA, KOXR, and KSBA.

KLAX...High confidence in TAF through 03Z with low confidence
after 06Z. There There is a 20% chance that cigs tonight will
hold off until at least 09Z. Good confidence that any east wind
component will be 5 knots or less.

KBUR...High confidence in TAF through 07Z with low confidence
after 09Z. There is a 30% chance that conds will remain VFR
tonight.
-- End Changed Discussion --

&&

.MARINE...21/834 AM.

Moderate confidence in forecast, except low-moderate confidence
for the inner waters N of Pt. Sal and in the western SBA Channel.

In the outer waters, Small Craft Advisory (SCA) level winds and
seas will become widespread today and continue much of the time
thru Sat. There may be a lull in the winds during the very late
night thru morning hours, especially Thu night/Fri morning. There
is a 30% chance of gales Wed afternoon/eve.

In the inner waters N of Pt. Sal, there is a 30% chance of SCA
level winds this afternoon/eve, and a 40-50% chance during the
afternoon/eve hours Wed. SCA level winds are likely during the
afternoon/eve hours Thu and Sat.

In the inner water S of Pt. Sal, there is a 30% chance of SCA
level winds in western portions of the SBA Channel this
afternoon/eve, then a 40-50% chance during the afternoon/eve
hours Wed thru Sat. Otherwise, SCA conds are not expected.

A long period south to southwest swell will subside late tonight
into Wed. This will create larger than usual breaking waves
nearshore and stronger currents near most harbor entrances.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement in effect through Wednesday afternoon
      for zones 87-362-366. (See LAXCFWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT Friday for
      zones 670-673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Rorke
AVIATION...Munroe
MARINE...DB/Schoenfeld
SYNOPSIS...Gomberg

weather.gov/losangeles

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