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Southwest California area forecast discussion 
National Weather Service Los Angeles/Oxnard California
150 PM PST Thursday Dec 25 2014

..new marine discussion...

Synopsis...

The blustery north winds will become northeasterly by Friday for
clear skies into the weekend with very cold temperatures in wind
protected areas. The clouds will increase early next week as a
dynamic cold low slides in with possible precipitation...gusty
winds...and cools the temperatures to below normal through midweek.

&&

Short term (today-sun)...skies were clear today except for a few
stratocu above the la County mountains winds will remain to be the main
issue over the next few days. Have downgraded the high wind warnings
across the sba/VT/la County mountains and sba South Coast to wind
advisories that will continue through much of Friday
afternoon...except through middle morning for the sba County mountains and
adjacent South Coast. There will continue to be a few isolated gusts
to 60 miles per hour across the usual outliers such as Whitaker Peak while
Malibu Hills could see isolated gusts to 60 miles per hour as well this
afternoon. Northerly winds will also continue to affect the Santa
Clarita...San Fernando valleys as well through this evening with
gusts to 40 miles per hour. Portions of West Los Angeles will experience winds
gusts to 30 miles per hour through early this evening.

Winds will begin to shift later this evening to a more traditional
Santa Ana northeast direction and persist into Friday afternoon.
This will bring more widespread winds across Ventura County valleys
and the northwestern portion of the San Fernando Valley. Winds
should die down across the la basin when this occurs. Some gusty
winds are likely across the San Gabriel valley foothills as
well...but should remain below Wind Advisory thresholds. As for the
winds through the short term...there should be a brief lull in the
winds Friday late afternoon through the early evening hours...then
another shot of cold air pushing into the High Desert will reinforce
stronger Santa Ana winds. Strong wind advisories will likely be
needed once again Friday night into Saturday. High temperatures will remain
quite cool on Saturday into the lower 60s while the Antelope Valley
might reach 50 degrees. These cold Santa anas will also reach Avalon
at Catalina Island...which will affect mariners who anchored in the
Bay.

The 24 hour change in temperatures was impressive ranging from 10 to 25
degrees cooler across the forecast area. Most coast and valleys will
only reach the lower to middle 60s today...while interior areas will be
even cooler.

For tonight ... will be a few interior areas that will be
dealing with hard freeze issues late tonight into Friday
morning...then once again Friday night into Saturday morning. Expect
low temperatures to be between 24-28 degrees across slo interior valleys
and Cuyama Valley. This will be the first significant freeze for
these areas. The Antelope Valley will see temperatures down to the lower
20s in wind protected areas as well. A hard freeze warning will
not be issued for the Antelope Valley as there have been two hard
freezes back in late November. Freeze warnings have also been issued
for the Santa Ynez Valley and the Ojai Valley with low temperatures
expected to be between 28 and 32 over the next few nights and early
mornings as well.

Overall...expect continued colder than normal high temperatures through
Sunday with a broad chilly northerly flow aloft. Highs will remain
in the 60s on Sunday. Winds will decrease for a brief time.

Long term (mon-thu)...both the GFS and European model (ecmwf) are in agreement that
a very cold and dynamic upper low will be retrograding towards
Southern California early next week and remain over the region into
at least Wednesday. At least that is what the last two model runs
were advertising. Reluctantly...in coordination with our neighboring
office have added slight chance probability of precipitation to the forecast beginning next
Tue-Wed. The reason I am reluctant about this...is just 24 hours
ago...the upper low was setting up just to the east of the forecast
area which had the potential to bring a damaging wind event to
la/vtu counties due to great upper level support. So that being
said...would not be surprised if models take the upper low back to
the east which would change the forecast from chance of rain...to
strong winds. So stay tuned. One thing for sure...it will be
extremely cold with this next upper low. Snow levels could be low
enough where the Santa Monica Mountains and Santa Clarita could see a
dusting. The timing of this upper low will be tricky as
well...especially with new years evening and people camping out for the
rose parade. Stay tuned as we get closer to this feature early next
week and get a better handle on what to expect. Ohio and...merry
Christmas.



&&

Aviation...25/1800z.

At 1736z...there was a surface based inversion with a top at 1800
feet and temperature of 13c.

Except for some MVFR to IFR conds on northern slopes of the l.A. And
vtu County mountains...expect VFR conds through the period. Gusty northwest to north
winds will affect much of Los Angeles County and sba County through
this morning. There will be areas of low level wind shear and strong uddf through the
morning. Winds will begin to diminish this afternoon.

Klax...high confidence in VFR conds through the period. Lower confidence
in the wind forecast. Gusty north Crosswinds will affect the Airport through
about noon...with occasional gusts to 25 knots. Expect some low level wind shear and MDT
to strong uddf this morning.

Kbur...high confidence in VFR conds through the period. Low confidence
in the wind forecast. Winds will likely be highly variable today. Expect
some low level wind shear and MDT to strong uddf this morning.

&&

Marine...25/200 PM PST.

For the outer waters...low to moderate confidence in gale force
northwest winds continuing through this evening. For tonight through
Saturday...the flow will turn north to northeast. At this time there
is moderate confidence in winds remaining at small craft levels
tonight through Friday morning...then below small craft levels
Friday afternoon through Saturday.

For the inner waters...moderate confidence that Small Craft Advisory
level winds will continue through this evening. Winds and seas
will subside tonight. Winds will shift to NE across the inner waters
late tonight. There is a 30 percent chance that the northeast winds
will reach small craft levels Friday morning near shore from Ventura
south to Santa Monica as well as waters east of Catalina Island.
Catalina Island faces another potential bout of northeast winds on
Saturday morning.

&&

Lox watches/warnings/advisories...
freeze warning (see laxnpwlox).
Wind Advisory (see laxnpwlox).
Gale Warning (see laxmwwlox).
Small Craft Advisory (see laxmwwlox).
High surf advisory (see laxcfwlox).
High rip current risk (see laxsrflox).

&&

$$

Public...Kaplan
aviation/marine...Sweet
synopsis...seto

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