Area Forecast Discussion
Issued by NWS Los Angeles, CA
FXUS66 KLOX 261208
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
508 AM PDT THU MAY 26 2016
An upper-level trough of low pressure will remain over the region
through early next week. Some weakening of the trough will take
place through Friday and lead to a warming trend, but low pressure
will reform west of the area and bring a cooling trend over the
weekend and into early next week.
Dry NW flow over the state as the weakest of ridges begins to move
into the nw portion of the state. The winds have diminished across
the SBA south coast and the wind advisory has been cancelled.
There will be another sundowner tonight with winds near low level
advisory criteria. There is a moist layer about 4000 feet deep
over the area. There is not much in the way of an inversion and
low clouds have struggled to form. the best stratus is over
western SBA county. Some stratus has formed over the Long Beach
area and the L.A. coast will have patchy low clouds this morning.
The vlys will dawn sunny this morning but the moist layer will
cook up into an afternoon stratcu deck as the morning sunshine
warms the ground. Lower than normal hgts will keep most max temps
3 to 6 degrees below normal.
The ridge will build in tonight and will smoosh the marine layer
as well as strengthening the inversion. Onshore flow will continue
and there will be a weak eddy as well. All of these factors will
add up to a pretty robust stratus layer that will blanket the
coasts and much of the vly area. Max temps will rise about three
degrees but will still be a few degree blo normal.
A saggy baggy trof moves into the area Saturday. But more
importantly an increase in high pressure across nevada will result
in decent offshore trends this will limit the low cloud vly
penetration and also delay the sea breeze some so while there will
be little in the way of warming at the coasts the vlys will see a
nice 3 to 6 degree jump allowing them to finally reach seasonal
EC and GFS are in good agreement for the long term forecast. Both
show trofing (deeper marine layer and cooler) for Sunday. Monday
will be a transition day the weak upper low departs and a
moderately sized ridge nears the coast. Its doubtful that there
will be much of a difference in conditions from Sunday. The ridge
will be over the area both Tuesday and Wednesday. The marine layer
will shrink and there will be limited vly morning clouds. The
marine layer will be smooshed pretty good across the coasts and
there will be a fairly robust inversion atop of it. This will
result in slower clearing for the coastal areas. The vlys will
warm which the coastal temps will change little from day to day.
At 1150Z at KLAX...The marine layer or moist layer was 5300 ft
deep with the top of the inversion at 6900 ft at 8 degrees celsius.
Moderate confidence with the 12z tafs in respect to better
organized marine layer stratus expected over the next 24-hours.
Cigs across the central coast ranged from IFR to MVFR. Lower
confidence for cigs along the coastal areas this morning. With
weak inversion, cigs could scour out earlier than posted. But
better confidence for mvfr/vfr cigs across inland tafs except
desert tafs today. 30 percent chance that ifr/mvfr cigs will not
develop at KPRB tonight into Early Friday morning.
Some llws possible around KSBA between 21z and 7z this eve.
KLAX...Moderate confidence in 12z TAF. There is a 30 percent
chance that MVFR cigs will only develop for a couple hours this
morning. If cigs do develop they will likely move in and out
before finally dissipating between 17Z and 18Z.
KBUR...Moderate confidence in 12z TAF. There is a 30-40 percent
chance that MVFR cigs will not develop through 15z this morning.
If cigs do develop they will likely rise to high MVFR or VFR
categories after 16z
Small Craft Advisories will continue across the outer waters
through Friday morning. SCA wind gusts will develop once again
across the western portion of the Santa Barbara Channel this
afternoon through mid evening hours. There is a 40 percent chance
that the inner waters between Point Piedras Blancas and Point Sal
could need a SCA for this afternoon through evening as well. But
for now have trended to weaker winds for that area. There is a 70%
chance that SCA level winds will affect the outer waters through
this weekend, with reduced confidence for Sunday.
Short period seas with dominant period of 6 to 8 seconds will
build to 8 to 10 feet through Friday under the gusty northwest
winds. Models were also hinting at a larger southerly long period
swell moving into the region in the middle of next week. Still a
ways away, but just wanted to mention.
PZ...Small Craft Advisory in effect from 3 PM this afternoon to 9
PM PDT this evening For zone 650. (See LAXMWWLOX).
Small Craft Advisory in effect until 9 AM PDT Friday For
zones 670-673-676. (See LAXMWWLOX).