Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 222235
AFDLOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
235 PM PST Wed Feb 22 2017

.SYNOPSIS...

Gusty winds and possible precipitation for the mountains into
Thursday morning. Elsewhere the clouds will decrease into Friday
and temperatures should stay below normal into Tuesday. One low
will arrive by Saturday night with precipitation into Sunday.
Then another low moves in on Monday and will continue the
precipitation into Tuesday.

&&

.SHORT TERM...(TDY-SAT)

Strong northwesterly flow is highlighted well on visible satellite
with streams of cloud development pushing up against the mountains
of the southern San Joaquin Valley. A good illustration as well of
the high moisture level of that air mass. It helps support the
forecast of mountain showers for this evening and overnight.
Updated model runs... though... have not only kept the high
humidities in the region but have also shown a much colder airmass
moving through tonight through Friday. This will drop snow levels
much lower than previously thought and will likely bring snow down
to the Grapevine section of Interstate 5 (the Tejon Pass).
There are indications of possibly one to two inches of snow at
pass level overnight. This will bear close watching and it is
entirely possible that a Winter Weather Advisory will need
to be issued this evening for the likelihood of snow through the
Tejon Pass.

While the possibility of snow below the Tejon Pass level is still
developing... the likelihood of strong and gusty winds through
the mountains through late Thursday morning looks more certain. The
strong winds are in part due to the cold dense airmass that would
be squeezing through the passes and canyons. The affected
mountains are the Santa Barbara... Ventura... and Los Angeles
County Mountains. In addition... strong and gusty winds are
expected in the Antelope and Santa Clarita Valleys and below
passes and canyons along the Santa Barbara South Coast this
afternoon and tonight. Areas along the Central Coast will be
affected primarily this afternoon and evening prior to the winds
turning more northerly.

Winds and mountain showers may linger a bit on Thursday and there
may be elevated winds through the Los Angeles County mountains
Thursday evening. However wind advisories are not expected at
this time. Conditions will continue to improve into Friday and
much of Saturday and though below normal... temperatures will be
warmer on Friday and Saturday.

The next storm system will begin to move into the region on
Saturday along the Central Coast. There may be a few periods of
light rain after midday but most of the precipitation should hold
off until Sunday.

.LONG TERM...(SUN-WED)

Precipitation will develop over the region on Sunday but there
continues to be uncertainty regarding how much and when. The
probability of rain has decreased across the region in general
though it still looks as though most locations should get wet.
Precipitation would begin along the Central Coast then move
southward through the day. However there had been a chance of an
extra shot of precipitation in the afternoon and evening into
Ventura and Los Angeles Counties and that is what has diminished
with recent model runs. The low appears to get hung up off shore
and then brings the extra shot of moisture in with the Monday
storm system instead. This would be helpful to the Academy Award
event planned for Sunday afternoon and evening but would make
Monday a messier weather day. Will need to see if this change
gets carried through into later model runs before making major
adjustments to the forecast package.

After a wet Monday and early Tuesday... a weak ridge will help
bring drier and warmer conditions to the region on Wednesday.

&&

.AVIATION...22/1800Z.

At 1632Z, there was no marine inversion at KLAX.

Poor confidence in the 18z TAFs. Some TAFS will have ceiling
changes this afternoon as a layer of stratocumulus develops in
some of the valley locations. Skies should clear out after dark.

KLAX...Moderate confidence in 18Z TAF. After 20Z, moderate
confidence in VFR conditions prevailing. This evening, after 02Z,
there will likely be some northerly cross winds with a 30% chance
of cross winds exceeding 25 knots.

KBUR...Moderate confidence in 18Z TAF. After 20Z, poor confidence
in VFR conditions. There is a 40 percent chance of sct v bkn
ceilings. There is a 30% chance of light turbulence/LLWS
developing after 02Z.

&&

.MARINE...22/200 PM...

For the Outer Waters, high confidence in current forecast.
Northwest winds will increase today, reaching Small Craft Advisory
(SCA) levels, with the SCA level winds continuing through Thursday
night. Winds and seas will diminish on Friday, but southerly winds
will increase on Saturday/Sunday with a high likelihood of SCA
conditions developing.

For the Inner Waters, high confidence in current forecast. West to
northwest winds will increase today, reaching SCA levels, with the
SCA level winds continuing through Thursday evening. On Friday,
winds and seas will diminish below SCA levels. However on
Saturday, southerly winds will increase to SCA levels north of
Point Sal with southeasterly winds increasing to SCA levels south
of Point Conception on Sunday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory in effect until 3 PM PST this afternoon
      for zones 34-35. (See LAXCFWLOX).
     Wind Advisory in effect until 9 PM PST this evening for zones
      34-35. (See LAXNPWLOX).
     Wind Advisory in effect until 10 AM PST Thursday for zones
      39-52>54. (See LAXNPWLOX).
     High Surf Advisory in effect until 9 PM PST Thursday for
      zones 40-41-87. (See LAXCFWLOX).
     Wind Advisory in effect until 3 AM PST Thursday for zones
      59-88. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 PM PST Thursday for
      zones 645-670-673-676. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PST Thursday for
      zones 650-655. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK...(SAT-WED)
Precipitation and wind are expected Saturday through Tuesday.

&&
$$

PUBLIC...Kj
AVIATION...Sweet
MARINE...Sweet
SYNOPSIS...STu

weather.gov/losangeles


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