002 
FXUS66 KLOX 252358
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA 
358 PM PST Tue Dec 25 2018

.SYNOPSIS...25/100 PM.

There will be dry northwest flow tonight into Wednesday, bringing
clear skies and slightly warmer temperatures to the area. A 
trough of low pressure on Thursday will bring cooler temperatures 
and gusty northerly winds, especially in the mountains. Surface 
high pressure building east of the area may bring cold Santa Ana 
winds to Southwest California on Friday.

&&

.SHORT TERM (TDY-FRI)...25/1250 PM.

Overall, 12Z models in good synoptic agreement through the short
term period. At upper levels, persistent northerly flow will
prevail through Friday. Near the surface, northwesterly flow will
prevail through Friday.

Forecast-wise, northerly flow is currently generating clouds
across interior sections of SLO/SBA counties as well as the
mountains of Ventura/LA counties. Expect these cloudy conditions
to continue through this evening, before clouds dissipate
overnight. There will likely continue to be a threat of some
showers across north-facing slopes through this evening with snow
levels around 4000 feet. So, winter weather conditions will remain
likely and will keep the current WINTER WEATHER ADVISORY in 
effect through 1000 PM this evening. For later tonight through 
Friday, skies are expected to remain mostly clear.

Other issue will be northwest to north winds across the area.
Gust northerly winds will continue across the area through this
evening and will keep current HIGH WIND WARNINGS and WIND
ADVISORIES in effect through 1000 PM this evening. Winds should
diminish late this evening with winds below advisory levels late
tonight and Wednesday. For Thursday and Friday, it looks like
northerly wind will be on the increase again with advisory level
winds likely Thursday through Friday morning in the usual spots
(Santa Ynez Range and Interstate 5 corridor). During the day on
Friday, winds should shift a little more to the northeast and
diminish.

As for temperatures, this pattern will keep temperatures at
seasonable levels through Friday.

.LONG TERM (SAT-TUE)...25/1250 PM.

Overall, 12Z models start out in good agreement then gradually
diverge through the long term period. At upper levels, low will
develop over the Arizona/Mexico border Saturday and Sunday. For
Monday and Tuesday, this feature moves eastward although the ECMWF
is noticeably faster with this progression than the GFS. Near the
surface, varying degrees of offshore flow will prevail.

Forecast-wise, main issue with the extended period will be winds.
Through the period, there will be varying amounts of northeast
winds across the area. At this time, it looks like the best
chances for significant northeast winds will be Saturday and
Sunday as upper level support lines up well with surface
gradients. So, would not be surprised to see widespread 
advisory-level northeast winds across the area with the strongest
winds in the usual spots across Ventura/LA counties. For Monday
and Tuesday, will expect the winds to decrease in strength
although the ECMWF would indicate a continuation of advisory level
winds. Will have to see how the models resolve themselves for
Monday and Tuesday.

Otherwise, mostly clear skies should prevail through the period as
offshore flow limits any stratus formation. Temperatures will
only vary slightly from day-to-day, hovering around seasonal
normals.

&&

.AVIATION...25/2355Z.

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

High confidence in the 00Z TAFs. Gusty NW to N winds are expected
north of Point Conception with gusty west to NW winds further
south, mainly during the evening hours. 

KLAX and KBUR...High confidence in the 00Z TAF with VFR 
conditions through the period. Gusty W winds expected through 03Z
at KLAX and through 05Z at KBUR but timing may differ by 1-2 hours
from taf times.

&&

.MARINE...25/129 PM.

For all the Outer Waters, high confidence in gale force winds
through late tonight. Combined seas are forecast to build up to 
15 to 18 ft through this evening then gradually subside through
Wednesday. Periods will be rather short with choppy seas. There 
is a 50%-60% chance that at least Small Craft Advisory (SCA) 
level winds and/or seas will persist Wednesday through Friday, 
with a 40% chance of gale force winds at times. Winds and seas 
should then remain below SCA levels for Saturday and Sunday.

For the Inner Waters north of Point Sal, high confidence in gale 
force winds through this afternoon, with a 30% chance that gales 
will continue through at least this evening or night otherwise
there is a 70% chance of SCA winds through late tonight. There is
a 40%-50% chance of SCA level winds at times Wednesday thru 
Friday. Winds and seas should then remain below SCA levels for 
Saturday and Sunday.

For the Inner Waters south of Point Conception, high confidence 
in gale force winds through this evening. Very large, steep and 
dangerous waves are expected thru tonight. SCA level wind gusts 
should prevail for a short time late this evening then drop below
SCA levels after midnight. Conditions should be below SCA levels 
on Wednesday and Wednesday night and again on Friday. There will
be a 30%-40% chance of SCA level wind gusts at times Thursday and
again Saturday and Sunday.

&&

.BEACHES...25/134 PM.

A large west-northwest swell continue to bring large surf to the 
Central Coast. Surf of 9 to 12 feet with peak sets up to 14 feet 
can be expected through this evening before slowly subsiding 
through Wednesday morning.

This swell will continue to bring high surf conditions to beaches
south of Point Conception through Wednesday morning. Surf of 5 to
8 feet with sets to 10 feet is expected on west-facing beaches, 
mainly in L.A. and Ventura Counties through this evening then
slowly subside overnight into Wednesday morning. Along the Santa 
Barbara County south coast, local sets up to 6 feet are expected. 
Strong rip currents are expected on all beaches, with a risk of 
sneaker waves and beach erosion.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory in effect until 9 AM PST Wednesday for
      zones 34-35-40-41-87. (See LAXCFWLOX).
     High Wind Warning in effect until 10 PM PST this evening for
      zones 39-52. (See LAXNPWLOX).
     Beach Hazards Statement in effect through Wednesday morning
      for zone 39. (See LAXCFWLOX).
     Wind Advisory in effect until 10 PM PST this evening for
      zones 41-46-59-88-547. (See LAXNPWLOX).
     Winter Weather Advisory in effect until 10 PM PST this
      evening for zones 53-54. (See LAXWSWLOX).
PZ...Small Craft Advisory in effect until 3 AM PST Wednesday for
      zone 645. (See LAXMWWLOX).
     Gale Warning in effect until 9 PM PST this evening for zones
      650-655. (See LAXMWWLOX).
     Gale Warning in effect until 3 AM PST Wednesday for zones
      670-673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK (FRI-TUE).

There is the potential for strong and gusty north to northeast 
winds Saturday and Sunday.

&&

$$

PUBLIC...Thompson
AVIATION...Smith
MARINE...Sirard
BEACHES...Sirard
SYNOPSIS...B

weather.gov/losangeles