Area Forecast Discussion
Issued by NWS Los Angeles, CA

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541
FXUS66 KLOX 230515
AFDLOX

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

.SYNOPSIS...

A weak weather system will bring some rain and snow to the
mountains through Thursday morning, along with gusty winds to many
areas. Otherwise, dry and cool weather can be expected through
Saturday. A couple of low pressure systems will bring rain and
continued cool weather to the area Saturday night through early
next week.

&&

.SHORT TERM...(WED-SAT)

Energy from a trough of low pressure over the Great Basin will
continue to move over the region this evening and into late
tonight. Shower activity earlier has ceased across most of the
area, except for the northern slopes of the mountians where clouds
and showers are developing. PoPs will remain in the forecast for
most valley and interior areas as some clouds are still lingering
and popping up as the colder air aloft punches in. With model
solutions indicating instability nosing into the mountains after
midnight, a wind advisory was converted to a winter weather
advisory due to the threat of accumulating snowfall and the
potential for icy roads in combination with the winds that were
already forecast to occur. With high-resolution NCEP WRF ARW and
NMM cores and latest NAM-WRF generating QPF values across the
northern slopes of the mountains, two to four inches of snow are
possible across the Los Angeles and Ventura County Mountains.
Local amounts up to seven inches cannot be ruled out across
higher peaks. Accumulating snow are forecast to occur on the
Grapevine later tonight, possibly impacting travel on Interstate
5.

Otherwise, winds will continue across portions of Los Angeles
County and across Southern Santa Barbara County. Gusty winds
likely will linger into Thursday night for most areas and the wind
advisories will likely be need to be extended or reissued by
future shifts for the Santa Clarita Valley and Southern Santa
Barbara County areas. A Wind Advisory will likely need to replace
the Winter Weather Advisory for the Los Angeles and Ventura County
Mountains.

***FROM PREVIOUS DISCUSSION ***

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...23/0000Z.

At 00Z, there was no marine inversion at KLAX.

VFR conditions should persist throughout the period, except for a
chance of IFR to MVFR conditions at KPRB. Periods of moderate to
strong wind shear and turbulence are possible through 20Z at
terminals south of Point Conception.

KLAX... VFR conditions are expected throughout the period.
Periods of moderate wind shear and turbulence are possible at KLAX
between 16Z and 20Z. There is a 50 percent chance of north winds
greater than 20 knots between 03Z and 08Z.

KBUR...VFR conditions are expected throughout the period. Periods
of moderate wind shear and turbulence are possible at KBUR through
16Z.

&&

.MARINE...22/900 PM.

Gusty winds and short-period hazardous seas will occur through at
least Thursday morning across the coastal waters, and possibly as
late as Thursday evening. A gale warning was added for near gale
force wind gusts and the threat of gale warning level winds will
continue through late tonight. Winds and seas will start to slowly
subside on Thursday into Friday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory in effect until 8 AM PST Thursday for zone
      39. (See LAXCFWLOX).
     Wind Advisory in effect until 10 AM PST Thursday for zones
      39-41-52-88-547. (See LAXNPWLOX).
     High Surf Advisory in effect until 9 PM PST Thursday for
      zones 40-41-87. (See LAXCFWLOX).
     Winter Weather Advisory in effect until 10 AM PST Thursday
      for zones 53-54. (See LAXWSWLOX).
     Wind Advisory in effect until 3 AM PST Thursday for zone 59. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 9 PM PST Thursday for
      zones 645-655-670. (See LAXMWWLOX).
     Gale Warning in effect until 3 AM PST Thursday for zones
      650-673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK...(SAT-WED)

More rain and wind is expected over the weekend.

&&

$$

PUBLIC...Hall/Kj
AVIATION...Hall
MARINE...Hall
SYNOPSIS...Sirard

weather.gov/losangeles



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