Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 270633
AFDLOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1133 PM PDT Sun Mar 26 2017

...Aviation discussion updated...

.SYNOPSIS...

A weak cold front may bring a few light showers to San Luis
Obispo County and the north slopes, beginning overnight into
Monday. Strong gusty north winds will begin Monday afternoon and
persist into Tuesday morning. A weak ridge and offshore flow will
bring warm and dry conditions by the middle of next week.

&&

.SHORT TERM...(SUN-WED)

Overall, it was a nice day across Southern California. High temps
trended upwards 1-5 degrees with best warming inland. Much of the
coast remained similar to yesterday in respect to high temps.
Plenty of high clouds were also hanging around today ahead of
weakening frontal boundary approaching NW SLO county later this
evening. There were some local gusty W winds occurring across the
western Antelope Valley with isolated gusts to 45 mph near Poppy
Park, and noticed SBA South Coast near Refugio was starting to
see gusts around 35 mph. Not expecting these winds to become
widespread so will hold off on a wind advisory this evening.

As the front reaches our forecast area it will wash out for the
most part. A few areas should recieve some light showers across
nrn SLO county. By Monday morning the main target for showers
will be across the northern slopes of the Santa Barbara, Ventura,
and NW portion of the LA county mtns. What showers that do occur
tonight into Monday will be less then a tenth of an inch. With
northerly flow expected to develop as this upper trough moves
through, clouds will linger across the northern slopes into early
Monday afternoon. The snow level will be around 6500 to 7000 ft as
this quick moving trough plunges through.

The main story for the next few days will be the wind developing
behind the exiting front. The combination of NW flow aloft and a
strong surface high (1030 mb) about 600 NM NW of Pt. Conception
and a 1007 mb low across the Lower Colorado Valley will cause a
strong NW to W surface gradient to develop. Initially, gusty NW
winds will pick up quickly across the Central Coast late Monday
morning with gusts to 35 mph expected. Then, northerly winds will
develop across the mountains and the SBA south Coast by the
afternoon. By Monday evening the potential for strong damaging
winds over 60 mph across the LA/VTU/SBA county mountains, Santa
Clarita Valley and the SBA South Coast will be possible. There
will be good upper level support at 850 mb for the northerly winds
beginning Monday evening into Tuesday morning. A high wind watch
is in effect for the mountains and Santa Clarita Valley are valid
starting Monday early evening through early Tue morning. The
western Antelope Valley might need to be added to the high wind
watch and will look closely at the 00z NAM model run to justify
adding a high wind watch there as well. Expect near advisory level
northerly winds to filter across the San Fernando Valley and into
West LA to Hollywood as well. By Tuesday morning the winds will
begin to shift out of the NE, a more typical Santa Ana wind
direction. There will continue to be decent upper lvl support
through the morning hours. More wind advisories will likely be
needed...especially across the wind prone LA/VTU county coast and
valleys.

***from previous discussion***

The offshore flow will bring a warming trend on Tuesday, with
the warmest valleys expected to climb into the lower 80s. The
warmest day of the week for many areas is expected to be Wednesday
when increased offshore flow at the surface and stronger upper
level ridging combine to bring temperatures approaching 90 degrees
in the warmest valleys.

.LONG TERM...(THU-SUN)

An inside slider will move down the NV/CA state line Thursday and
then into Arizona on Friday. Still a bit questionable how much
cooling this system will bring to the region as GFS maintains
higher heights than EC during this period. GFS and EC models
coming into better agreement on bringing a resurgence of offshore
flow and warming temperatures next weekend, with inland areas
climbing well into the 80s.

&&

.AVIATION...27/06Z...

At 03Z at KLAX... the inversion was based at about 4800 feet. The
top of the inversion was around 6900 feet with a temperature of
eight degrees Celsius.

Overall... Moderate confidence in the current TAFs. MVFR
conditions are possible at most locations overnight other than in
the Antelope Valley. Chances are greatest for terminals along the
Central Coast and along the Los Angeles County coast. There is a
slight chance of showers at San Luis Obispo County terminals
08z-13z. All sites will become VFR by 16z-18z as winds become
strong and gusty through 03z. Antelope Valley sites remain VFR
throughout the forecast period.

KLAX... Moderate confidence in the current TAF. MVFR conditions
are likely 09z-17z otherwise VFR conditions will prevail. Winds
become strong and gusty 21z-03z. No east winds greater than seven
knots are expected.

KBUR... Moderate confidence in the current TAF. There is a less
than ten percent chance of MVFR conditions developing overnight.
Otherwise VFR conditions will prevail.

&&

.MARINE...26/800 PM...

For the Outer Waters, high confidence in current forecast.
Northwest winds will be on the increase through Monday night
with Gale force winds likely Monday afternoon and night.
Gale force gusts are likely through Tuesday morning...but will
diminish a bit Tuesday/Wednesday. However, winds will still
remain at SCA levels through this time. For Thursday and Friday,
there is a good chance that winds will increase to Gale force
again.

For the Inner Waters, moderate to high confidence in current
forecast. For the waters north of Point Sal, high confidence in
winds reaching Gale force Monday afternoon/evening with winds
hovering around SCA levels Tuesday through Friday. For the waters
south of Point Conception, moderate confidence in winds increasing
to Gale force levels Monday afternoon and night (mainly across
western sections) with winds hovering around SCA levels Tuesday
through Friday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect from noon to 9 PM PDT Monday for
      zones 34-35-59. (See LAXNPWLOX).
     Wind Advisory in effect from noon to 6 PM PDT Monday for
      zones 39-52>54-88. (See LAXNPWLOX).
     High Wind Watch in effect from Monday evening through Tuesday
      morning for zones 39-52>54-88. (See LAXNPWLOX).
PZ...Gale Watch in effect from 11 AM PDT Monday through late
      Monday night for zones 645-650-655. (See LAXMWWLOX).
     Small Craft Advisory in effect until 11 AM PDT Monday for
      zones 650-670-673-676. (See LAXMWWLOX).
     Gale Watch in effect from 11 AM PDT Monday through Tuesday
      morning for zones 670-673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK...(WED-SUN)
Another round of strong and gusty northwest to north winds will
be possible Thu night in the mountains and along the Santa Barbara
County south coast, with travel being affected by the winds.

&&
$$

PUBLIC...Kaplan/Gomberg
AVIATION...Kj
MARINE...RAT/Smith
SYNOPSIS...B

weather.gov/losangeles



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