National Weather Service Text Product Display

Area Forecast Discussion
Issued by NWS Los Angeles, CA
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FXUS66 KLOX 010542 AAA
AFDLOX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
942 PM PST Tue Jan 31 2017

...update for new aviation discussion...

.SYNOPSIS...
A low will approach by Wednesday evening for possible
precipitation for Santa Barbara County and northward. The chance
of precipitation should spread into Ventura and Los Angeles
Counties on Thursday and Friday, and linger in the mountains on
Saturday. Another low may bring possible precipitation from Sunday
night into late Monday. Temperatures will hover around normal into
early next week.

&&

.UPDATE...

Generally quiet wx covered the forecast area this evening with
mostly clear skies for most areas altho some hi clouds were moving
into SLO/SBA Counties. The latest fog product imagery shows low
clouds and fog over the coastal waters off the Central Coast and
along and off the San County coast, with dense fog being reported at
KSAN. The NAM was forecasting s to se flow over the SoCal bight
overnight into Wed morning, with the possibility of the low clouds
and patchy dense fog expanding up the coast to L.A./VTU Counties
late tonight into Wed morning. Otherwise, mostly clear skies with
some hi clouds at times can be expected across southwestern CA thru
the night.

&&

.SHORT TERM...(TUE-FRI)

Synoptically, the upper level ridge that has been mostly
stationary over our area is shifting east ahead of a cutoff low
presently west of northern california.

By Wednesday, A strong 540 DM low will be around 850 miles west
of San Francisco. This low will then transit to the NE keeping
the best storm dynamics to the north of our forecast area. There
will be some increasing clouds on Wednesday ahead of the storm
system that will mostly affect areas N of Point Conception by very
late Wednesday night or early Thursdsay morning with light to
locally moderate rain. Rain will begin in the NW portion of SLO
county then spread across most areas N of Point Conception by
Thursday afternoon. As the front moves past Pt. Conception, it will
weaken considerably and rain amounts should be very light across
VTU and LA counties through Friday. Rainfall totals for LA county
should be less than a tenth of an inch in most areas Thursday.
Slightly higher possibly around the San Gabriel Foothills and Vtu
County. At this point, not expecting any flooding issues for the
recent burn areas as hourly rainfall rates will be not high.

Coasts and valleys will have a hard time making out of the 60s,
on Wednesday with cooler conditions across the higher terrain.
Southerly winds will freshen on Wednesday and it could be fairly
breezy on the Santa Barbara south coast by late afternoon.

Thursday brings another 2 to 5 degrees of cooling as the rain
spreads over much of our forecast area, although it looks to stay
focused on coastal areas south of Point Conception.

There will continue to be residual moisture moving in across the
forecast area on Friday, with LA County actually having a better
shot of measurable rain compared to Thursday. Nonetheless, not
expecting much more precip over LA/VTU counties. There will be
some additional rainfall over SBA/SLO counties. By the time this
system moves out late Friday night, most areas N of Point
Conception should have received a quarter to half inch, while
LA/VTU should remain less than a quarter inch.

There will be gusty SW winds across the Antelope Valley and
continued gusty SE to S winds across all areas N of Point
Conception on Friday.

.LONG TERM...(SAT-TUE)

Clearing is expected on Saturday, but still expecting partly
cloudy skies...especially across inland areas, valleys, and
mountain areas. With the return of some sun there is a slight warm
up for the weekend before the next system arrives in the early
hours of Monday.

Both the EC and GFS are in pretty good agreement regarding another
storm moving across the forecast area late Sunday night through
Monday. This storm looks like it will be stronger than the
Thursday rain, including possible instability. Pops cover our
forecast area for the day. Snow levels should be around 5500 to
6000 ft. With this system still almost a week away will hold off
on details and rainfall totals.

&&

.AVIATION...01/0535Z

At 0401Z, there was a surface-based inversion at KLAX. The top of
the inversion was around 1300 ft with a temperature of 18 deg c.

Generally hi confidence overall in the 06Z TAFs, except moderate
confidence in LIFR cigs at KSMX, KLAX and KLGB early to mid Wed
morning, with a 50 percent chance of these cigs developing. There is
also a 50 percent chance of MVFR vsbys at KSBP Wed morning.
Otherwise, VFR conditions can be expected at all the airfields thru
Wed evening.

KLAX...Generally hi confidence overall in the 06Z TAF, except
moderate confidence in LIFR cigs from 14Z to 17Z Wed morning, with a
50 percent chance of these cigs developing. There is also a 60-70
percent chance of LIFR/MVFR cigs from 08Z-12Z Wed night. Otherwise,
VFR conditions can be expected at the airfield for much of the
forecast period.

KBUR...Hi confidence in the 06Z TAF with VFR conditions expected
through Wed evening.

&&

.MARINE...31/800 PM.

High confidence that winds and seas will remain below SCA levels thru
early Wed, then south winds will increase Wed afternoon and Wed night
ahead of a frontal system. Good confidence in SCA conditions across
the outer waters and northern inner waters Wed afternoon thru Thu night
or Fri morning. There is a 20-30% chance of Gale force winds across
the northern two outer waters zones late Wed night thru Thu evening.

There is a 30-40% chance of SCA conds across the SBA channel Thu and
Thu night, and a 20% chance of SCA conds across the southern
inner waters Thu afternoon into Thu night.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.

&&

.HAZARD POTENTIAL OUTLOOK...(FRI-TUE)
A chance of rain for most of the area on Thursday and Friday with
a stronger system arriving Sunday night into Monday morning. None
look to be significant flooding threats at this time.

&&

$$

PUBLIC...jld/Sirard
AVIATION...Sirard
MARINE...Sweet/Sirard
SYNOPSIS...Stu

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