Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 210005 AAA
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
405 PM PST Wed Feb 20 2019

updated aviation discussion

.SYNOPSIS...20/115 PM.

Today will be cloudy with a chance of showers and mountain snow
as another storm system moves into the region. The chance of rain
and snow with windy conditions lasts through Thursday, and cold
temperatures could lead to snow at lower elevations. Dry weather
is expected by Friday, and temperatures will gradually warm into
next week.

&&

.SHORT TERM (TDY-SAT)...20/156 PM.

Cold upper low dropping south along the West Coast has already
generated some light showers across the far western portion of
the forecast area, mainly west of a line from Goleta up through
interior SLO County. Expecting these to spread south and east
through the evening, though again the downsloping effects from the
northwest flow over the Transverse ranges will dissipate at least
some of the precip, especially western Ventura County and
southeastern SB County. But even in those areas there should be
some light precip that may or may not result in measurable rain.
This pattern to continue through Thursday with the added potential
of thunderstorms as the air mass becomes slightly unstable. These
could generate some brief heavy downpours with small hail or
graupel just about anywhere but given the overall lack of moisture
with this system we`re not expecting rain rates to pose any issues
for burn areas.

The biggest impact locally will be the extremely low snow levels
and likely significant delays and closures of major roads through
the mountains tonight and Thursday, including Interstate 5
through the Grapevine and possibly even Highway 14 from Santa
Clarita to the Antelope Valley. Some of lower highways could even
be impacted at times including Highway 101 through Cuesta Pass in
SLO County and Highway 154 through San Marcos Pass in SB County.
Interstate 5 likely to be the biggest concern due to the
combination of strong northwest flow pushing the moisture up the
north facing slopes and very cold temps. Could see 3-6" of snow
accumulation at pass level. Thicknesses bottom out at around 526dm
which if true could result in snow down to 1000` or even slightly
lower. A Winter Weather Advisory is in effect for all the
mountains and interior valleys through Thursday evening.

Showers expected to taper off by Thursday night with dry but cold
weather Friday. Will be issuing a Freeze Watch for late Thursday
night into Friday morning for the Central Coast and the valleys of
LA/Ventura Counties as clearing should happen early enough for
temps to drop to near or below freezing in many areas.

Another cold night Friday night followed by a cool but slightly
warmer day Saturday but with temps still a good 5-10 degrees
below normal in most areas.

.LONG TERM (SUN-WED)...20/205 PM.

Pretty quiet through the middle of next week. Temps will remain
below normal through the early next week but then should be
getting very close to normal by Tue/Wed as a ridge of high
pressure sets up along the West Coast that should last at least
through Friday.

&&

.AVIATION...21/0004Z.

At 2330Z at KLAX...there was no marine inversion present.

Moderate confidence overall in the 00Z TAFs. A cold and showery
pattern will prevail thru Thu morning at all the airfields, with
mostly VFR cigs expected with off and on showers. However, there
is a 40% chance that some heavier showers could lower cigs/vsbys
to MVFR at any time during the period. Most of the showers should
end by Thu afternoon with generally hi confidence of VFR
conditions at the airfields at that time. Gusty W to NW winds at
most coastal airfields and at KPMD and KWJF will prevail thru this
evening.

LAX...Moderate confidence overall in the 00Z TAF. Mostly VFR cigs
are expected with off and on showers thru Thu morning. However,
there is a 40% chance that some heavier showers could lower
cigs/vsbys to MVFR at any time during the period. The showers
should end by Thu afternoon with generally hi confidence of VFR
conditions thru Thu evening. Gusty W winds will prevail at times
thru this evening.

KBUR...Moderate confidence overall in the 00Z TAF. Mostly VFR
cigs are expected with off and on showers thru Thu morning.
However, there is a 40% chance that some heavier showers could
lower cigs/vsbys to MVFR at any time during the period. The
showers should end by Thu afternoon with generally hi confidence
of VFR conditions thru that period.

&&

.MARINE...20/136 PM.

For the Outer Waters, moderate to high confidence in current
forecast. High confidence in Small Craft Advisory (SCA) level
northwest winds today through Thursday night with a 70% chance
of SCA level winds continuing through Friday evening. There is
a 30% chance of GALE force gusts this afternoon through Thursday
evening. For Saturday and Sunday, moderate confidence in SCA level
winds continuing.

For the Inner Waters north of Point Sal, moderate to high confidence
in current forecast. High confidence in Small Craft Advisory (SCA)
level northwest winds during the afternoon and evening hours both
today and Thursday. There is a 40% chance of SCA level winds
developing again Friday afternoon/evening. After a lull on
Saturday, there is a 50% chance of SCA level winds Sunday
afternoon and evening.

For the Inner Waters south of Point Conception, moderate to high
confidence in current forecast. High confidence in SCA level west
to northwest winds this afternoon through tonight. For Thursday
and Thursday night, moderate confidence (50% chance) in SCA level
winds continuing. After a lull on Friday and Saturday, there is a
40% chance of SCA level winds across western sections on Sunday.

For all waters, there is a slight chance of thunderstorms Thursday
and Thursday evening.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Freeze Watch in effect from late Thursday night through
      Friday morning for zones 34>36-44>46-88-547. (See LAXNPWLOX).
     Winter Weather Advisory in effect until 10 PM PST Thursday
      for zones 37-38-51>54-59. (See LAXWSWLOX).
PZ...Small Craft Advisory in effect until 3 AM PST Thursday for
      zones 645-650-655. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PST Friday for
      zones 670-673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK (SAT-WED).

No significant hazards expected.

&&

$$

PUBLIC...MW
AVIATION...Sirard
MARINE...Sweet
SYNOPSIS...Phillips

weather.gov/losangeles



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