-- Discussion containing changed information from previous version are highlighted. --
599
FXUS66 KLOX 220038
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
538 PM PDT Tue May 21 2024

.SYNOPSIS...21/236 PM.

Higher chances of sunshine with slight warming is expected Wednesday
as onshore flow weakens. Then cooler with increasing marine layer
clouds again the latter half of next week, followed by a warming
trend starting Sunday.

&&

.SHORT TERM (TDY-FRI)...21/204 PM.

The broad positively tilted trough will persist over the region
with minimal changes through Thursday. Onshore flow decreased
today, resulting in a break from cloudy skies. This morning some
coastal areas saw sunny to partly cloudy sunrises, followed by
complete clearing across the region (except for the eastern Santa
Barbara south coast) by the afternoon. Very low confidence in the
low cloud forecast tonight into tomorrow morning. There is a
30-50% chance of sunny skies by the mid Wednesday morning for the
majority of coastal areas, and will offer the best opportunity for
sunny skies Santa Barbara County South Coast through Friday.
By Wednesday afternoon, NW to W winds will strengthen across the
Antelope Valley and foothill and the I-5 cooridor. At this time
winds will likely remain below advisory levels, with gusts 25 to
40 mph common.

Thursday, the wide upper level trough will intensify, and onshore
gradients will increase. Marine layer clouds will likely linger
longer into the day, especially near the coast, and this will
cause temperatures to trend downward by around 1 to 3 degrees.
Highs will be 3 to 6 degrees below normal, locally up to 10
degrees.

Friday a shortwave trough, embedded in the larger troughing
pattern, will quickly pass over the region. This disturbance may
support night to morning marine layer drizzle for coastal areas
and a 5-10% chance of afternoon showers/thunderstorms for interior
mountains. Significant onshore flow and a cooling airmass aloft
will drop temperates to 6 to 10 degrees below normal (locally up
to 13 degrees). Friday will likely be the coldest day of the
forecast period, with daytime highs in the low- to- mid 60s for
coasts, around 65-70 for valleys, and mid 70s for deserts.

.LONG TERM (SAT-TUE)...21/226 PM.

The GFS and ECMWF are in good agreement for the weekend into
early next week. By Saturday, the shortwave trough will have
exited the region, with the board upper level trough remaining.
Typical deep marine layer clouds are likely to extend across the
coasts and valleys, with minimal chances of clearing for coastal
areas. Onshore gradients will maintain gusty winds across the
interior areas during afternoon and evening, particularly for the
Antelope Valley and foothills.

Sunday through Tuesday, upper level heights are expected increase,
resulting in a weak ridging pattern. The marine layer clouds will
lower in height, due to the higher pressure, and will not reach
as far inland. The warm airmass aloft combined with the reduction
in the influence of marine layer clouds, will result in a general
warming trend for all areas, excluding near coastal locations.

&&

.AVIATION...
-- Changed Discussion --
22/0035Z.

At 2343Z at KLAX, the marine layer was 1400 ft deep. The top of
the inversion was at 4800 feet with a temperature of 16 C.

High confidence in KPMD, KWJF, and KPRB TAFs.

High confidence elsewhere through 03Z, then low confidence.
Timing of cigs may be off by 3 hours and off by 1 flight cat.
There is a chance that VFR conditions prevail for KBUR(30%),
KVNY(30%), KCMA(20%), KOXR(20%), and KSBA(30%). There is a 20%
chance of no clearing at KLAX and KSMO through the period.

KLAX...High confidence in TAF through 03Z, then low confidence.
There is a 20% chance that cigs tonight will hold off until at
least 09Z. There is a 20% chance of no clearing through the
period Good confidence that any east wind component will be 5
knots or less.

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

&&

.MARINE...21/132 PM.

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 through early this evening 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 20% 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 continue to subside
through Wed. Larger than usual breaking waves nearshore and
stronger currents near most harbor entrances will become less
common during this time frame.

&&

.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...Schoenfeld/Munroe
AVIATION...Lund
MARINE...DB/Schoenfeld/RM
SYNOPSIS...Gomberg/Schoenfeld

weather.gov/losangeles

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