Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 251630

930 AM PDT Thu May 25 2017

The low will push the marine layer...possible precipitation and
below normal temperatures farther inland into Saturday. A high will
build in over the weekend to push the marine layer back to the coast
with above normal temperatures for early next week. Another low may
approach near midweek for increasing clouds and cooling trend.



The marine lyr has deepened on schedule, now up to 4500` south of
Pt Conception and 3500-4000` up north. The only real question now
is has it deepened enough to actually get a reverse clearing
pattern where it clears better at the coast but stays cloudy
inland. Based on the visible satellite imagery this morning it
doesn`t appear that we`re headed for that situation today, but
tomorrow might prove to be a better setup for that with some
additional deepening expected with the trough and some PVA aloft.

Otherwise, no big changes to the forecast through the middle of
next week as the models have been pretty consistent showing a
ridge developing late in the weekend and another trough for the
middle of next week.

***From previous discussion***

The deep marine layer and a little PVA from the upper trof will
bring a better chance of drizzle to the area tonight. In fact the
PVA when combined with the orographic lift provided by the
foothills will bring a chc of light rain to the coastal slopes esp
for the San Gabriels.

Friday will be much like today. The onshore flow will be a little
weaker and and the trof will be to the east so there will be a
little better clearing and maybe a little warmer temperatures away
from the coast.

A more typical marine layer pattern sets up for Saturday. There
will be moderate onshore flow and fairly deep marine layer capped
by a weak to moderate inversion. Low clouds will make it into the
vlys but there will be total clearing by mid or late morning. Max
temps will rebound 3 to 6 degree but will still be a few degrees
blo normal.


The little ridge that moved into the area Saturday will continue
to grow and will smoosh the marine layer down and mostly out of
the vlys. Max temps will climb to near normal at the coasts and
above normal inland.

The ridge will exit the area Monday but not so fast that it will
bring any cooling to the area in fact due to the warmer overnight
airmass max temps will likely climb a few more degrees across most

The EC and GFS agree that an upper low will form near SRN CA Tue
and Wed but they do not agree on exactly where it will set up. The
EC has the upper low closest to SRN CA and it would produce a
cooler cloudier scenario. The GFS has the upper low a hundred
miles of so south of KSAN. If the GFS comes to pass there will be
much less clouds with warmer temps. For this forecast favored the
cooler EC soln.



At 0935Z, the marine inversion at KLAX was based at 3200 feet. The
top of the inversion was 4300 feet with a temperature of 17
degrees Celsius.

Overall, moderate confidence in 12Z TAF package. There is a 30%
chance that CIGs this afternoon could increase to VFR levels and a
20% chance that CIGs could scatter out across coastal and valley
TAF sites. For tonight, high confidence in return of MVFR CIGs,
but only moderate confidence in timing.

KLAX...moderate confidence in 12Z TAF. There is 30% chance that
CIGs will increase to VFR levels 20Z-02Z and a 10% chance that
CIGs could dissipate 20Z-03Z.

KBUR...moderate confidence in 12Z TAF. There is 30% chance that
CIGs will increase to VFR levels 20Z-02Z and a 10% chance that
CIGs could dissipate 20Z-03Z.


.MARINE...25/900 AM.

High confidence sub-Small Craft Advisory (SCA) conditions through
Friday. Southwest winds up to 20 KT are expected near the coast
from Ventura to Orange County this afternoon and evening...which
will create locally choppy seas. Typically gusty northwest winds
should reform over the weekend...with SCA certain from the Central
Coast to San Nicolas Island...and short period seas for the Santa
Barbara Channel and Santa Monica Basin. There is a 30 percent
chance for SCA conditions over the western half of the Santa
Barbara Channel on Sunday.


CA...Wind Advisory in effect from 1 PM this afternoon to 9 PM PDT
      this evening for zone 37. (See LAXNPWLOX).
     Wind Advisory in effect until 9 PM PDT this evening for zone
      59. (See LAXNPWLOX).


No significant hazards expected.



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