Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 271242

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
542 AM PDT Fri May 27 2022

.SYNOPSIS...27/1205 AM.

Weakening high pressure and increasing onshore flow will bring a
cooling trend to the area through the weekend. A persistent
marine layer will continue to affect coastal areas, expanding
into the valleys and coastal slopes of the mountains today and
Saturday. Gusty onshore winds are expected each afternoon and
evening for the mountains and interior valleys. A warming trend is
expected by next Tuesday.


.SHORT TERM (TDY-SUN)...27/301 AM.

A weak trof is moving over the west coast. There is moderate
onshore flow both to north and more so to the east. These two
factors have lifted the marine layer to 3000 or more ft and
stratus clouds cover all of the csts/vlys/coastal slopes as well
as most of SLO county. The afternoon push to the east will be
around 9 mb again and this along with the gentle lift from the
trof will make it a no clearing day at many beaches and slow
clearing elsewhere. That same 9 mb gradient will also produce 40
mph gusts in the Antelope Vly foothills. Lower hgts and a deeper
marine layer will knock 3 to 6 degrees off of max temps today Max
temps will end up 4 to 8 degrees blo normal today.

A little north push develops tonight. It will bring a mild
sundowner and some gusty I-5 corridor winds - very likely sub
advisory. These winds may limit the low clouds across portions of
the SBA south coast although there will be an eddy so it will be
almost a 50/50 cloud/no cloud proposition. Elsewhere the eddy will
bring a similar stratus pattern.

Not that much change in Saturday`s weather compared to today. The
SBA south coast clouds may clear faster with the north flow along
with some warming.

A stronger north push Saturday night and a much weaker eddy will
limit the low clouds with many vly locations remaining clear and
also the SBA south coast. Advisory level gusts will likely
develop across the western portion of the SBA south coast, the I-5
corridor and the NW portion of the Antelope Vly.

Sunday will see much quicker and much better clearing with all
areas under sunny skies by late morning (if not earlier). The lack
of marine layer and north push will bring 4 to 8 degrees of
warming to the coasts and vly. Cool air advection will cool the
interior by 2 to 4 degrees.

.LONG TERM (MON-THU)...27/137 AM.

Both the deterministic GFS and EC as well as their respective
ensembles (GEFS, EPS, GPS) are in good agreement for the xtnd
period which translates to better than average confidence in the
Monday through Thursday forecast.

This weekends trof will shift just far enough to the east to bring
dry moderately fast NW flow aloft to the state.  The N/S grads
turn offshore in the morning and on Monday they will combine with
strongest winds aloft to produce a decent NW to N wind event
across the SBA/VTA/LA mtns as well as the SBA south coast and the
NW portion of the Antelope Vly.

There will be significant reduction in the onshore flow to the
east (The EC actually has a little morning offshore flow). The N/S
gradients will be weakly offshore in the morning and then weakly
onshore in the afternoon. At this time no significant eddy is
forecast and there should not be much marine layer stratus Monday
through Wednesday.

Max temps will not change much Monday but there will be
significant warming both Tue and Wed as the onshore flow weakens
and the marine layer shrinks. By Wednesday the valleys will have
max temps in the mid and upper 80s with a smattering of lower 90s.

Troffing, stronger onshore flow and much more marine layer stratus
return on Thursday and will spark a significant cooling trend.



At 12Z at KLAX, the marine layer was 2600 feet deep. The top of
the inversion was around 4600 feet with a temperature of 19 C.

Low clouds widespread across the entire region except for the
mtns and Antelope Valley. Conds were mostly MVFR, except IFR to
LIFR in the foothills and lower mtns slopes. Skies should clear by
late morning in the valleys and during the afternoon across the
coastal plain. Clouds could linger near the coast through the day.
Expect an early return of low clouds tonight, with clouds
expected in all coastal and valley areas. Conds will be MVFR,
except IFR to LIFR in the foothills.

KLAX...Moderate confidence in the 12Z TAF. There is a 20-30%
chance that cigs will linger through the day. High confidence in
any east wind component will remain under 7 kts through tonight,
then there is a 20-30% chance of SE-E winds reaching 7kt.

KBUR...Moderate confidence in the 12Z TAF. There is a 20-30%
chance that cigs will linger through 21Z. There is a 20-30% chance
that cigs will arrive as early as 03Z.


.MARINE...27/530 AM.

Across the outer waters, after a fairly quite day, Small Craft
Advisory (SCA) level NW winds are expected to spread from north to
south this evening and early tonight, then continue through Sat.
Winds will increase additionally Sat afternoon, and Gale force
winds are possible Sat afternoon all the way thru late Mon night.
SCA conds are expected Tue. Seas are expected to build over the
weekend, becoming dangerous and steep with heights potentially
peaking near 15 feet Sun into Mon.

Across the inner waters north of Pt. Sal, SCA level NW winds are
expected during the afternoon and evening hours Sat thru Mon.
Seas will likely remain above SCA levels when winds drop off at
night. There is a 20-30% chance of Gale force winds Sun and Mon.

Across the Santa Barbara Channel, there is a 20% chance of SCA
level W-NW winds this evening across western portions. SCA level
W-NW winds are likely during the late afternoon through late
night hours Sat through Tue, and may continue most of the time
across western portions. There is a 20-30% chance of Gale force
winds across western portions during the afternoon and evening
hours Sun and Mon.

Across the southern inner waters, there is a 40% chance of SCA
level W-NW winds across western portions late Sat afternoon and
evening, then SCA conds are likely late Sun into Sun night, and
Mon afternoon into Mon night.

Seas across the inner waters will become dangerous and steep with
heights potentially peaking near 10 feet Sunday thru Mon.

Gradual improvement is expected heading into the middle part of
next week.


PZ...Small Craft Advisory in effect from 6 PM this evening to 3 PM
      PDT Saturday for zones 670-673. (See LAXMWWLOX).
     Gale Watch in effect from Saturday afternoon through late
      Monday night for zones 670-673-676. (See LAXMWWLOX).
     Small Craft Advisory in effect from 11 PM this evening to 3
      PM PDT Saturday for zone 676. (See LAXMWWLOX).




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