Area Forecast Discussion
Issued by NWS Los Angeles, CA
FXUS66 KLOX 040416
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
816 PM PST Sat Dec 3 2016
Locally gusty Santa Ana winds will diminish through Sunday
morning, but warming will continue due to weak offshore flow. Low
pressure will move through the Great Basin early next week,
resulting in locally gusty north winds and cooler weather. Warming
is likely for mid-week as offshore flow develops. A frontal
system may bring rain north of Point Conception late in the week.
Evening forecast looks to be in good shape. Skies were mostly
sunny today with high temps up 3-6 degrees up across most coast
and coastal valleys. Interior areas were up around 6-10 degrees
while a few lower mountain locations were up as much as 12 to 20
degrees. Mt Wilson went from 43 on Friday to 63 today. Expect
skies to remain clear overnight. Only change this evening will be
adding a freeze warning for the wind protected Ojai Valley for
early Sunday morning. Although there will be a few degrees of
warming tonight compared to last night, lows early this morning
dipped to the upper 20s at Ojai.
Winds across most valleys and coastal areas of Los Angeles and
Ventura counties have diminished to well below advisory levels.
However wind gusts were still slightly below sub-advisory levels
across the LA/VTU county Mtns. Gusts were ranging between 30 and
40 mph with Chilao the one exception where gusts were in the
upper 40s. Winds across the LA county mtns expected be remain a
bit gusty with local gusts reaching advisory levels after
midnight through early Sunday. Some gusty offshore winds will
redevelop across portions of the eastern Ventura County valleys
overnight but should also remain just below advisory levels with a
few gusts reaching 35 mph. Overall, winds should be much weaker
than the past few nights going into Sunday morning.
An upper level low over nwrn Mexico this afternoon will drift e thru
Sun. At the same time, upper level ridging over the eastern Pac will
extend into srn CA, with the ridge axis at its max over the area Sun
morning. The upper ridging will weaken Sun night, with broad upper
level troffiness expected to move into CA on Mon along with a
dissipating cold front into swrn CA. A broad nw flow aloft can be
expected over swrn CA Mon night and Tue, with 500 mb heights around
568 dm or so.
Skies are expected to be mostly clear across the region tonight thru
Mon, except possibly some marine layer low clouds may develop along
the L.A./VTU County coast by Mon morning as an eddy forms over the
SoCal bight. Patchy low clouds and fog may develop in the Salinas
River Vly later Sun night into Mon morning as well.
Some mainly mid level cloudiness is expected over the area Mon night
into Tue morning, with mostly sunny skies Tue afternoon. There
should also be varying amounts of marine layer clouds and fog from
the coast to the vlys of VTU/L.A. Counties Mon night into Tue
morning, altho the 18Z NAM was indicating some offshore flow may
push the low clouds off the coast by early Tue morning.
Gusty ne winds will continue tonight and Sun morning, especially in
the favored areas of VTU/L.A.Counties, but be mostly below advisory
levels. Gusty n canyon winds should affect the SBA County mtns and s
coast Sun night, with gusty nw winds in the L.A./VTU County mtns
along the I-5 corridor, and gusty w to nw winds in the Antelope Vly,
which may linger into Mon morning. Another round of gusty nw winds
should affect the L.A. County mtns along the I-5 corridor Mon
night, with gusty w to nw winds into the Antelope Vly.
Daytime temps are forecast to warm to several degrees above normal
for many areas Sun before cooling to near normal to slightly below
normal on Mon, and to about 4 to 8 deg below normal on Tue. Highs in
the warmest coast and vly areas will be in the 70s on Sun, mid 60s
to around 70 on Mon and mid 60s on Tue. Clear skies and a dry air
mass will bring another round of sub-freezing temps to the SLO
County interior vlys tonight, where areas of frost is expected.
Patchy frost can also be expected tonight in the Ojai vly.
The GFS and EC are in generally good agreement in the synoptic scale
Wed thru Sat. A weak shortwave upper trof should move thru srn CA on
Wed followed by weak upper level ridging into the area Thu thru Sat,
altho the EC is somewhat weaker on Fri.
A weak cold front should move into nrn SLO County Fri afternoon,
then remain stationary over the area thru Sat, bringing mostly
cloudy skies mainly to SLO/SBA Counties, and a slight chance of rain
to nrn SLO County at times. Otherwise, clear to partly clouds skies
should prevail over the forecast area Wed thru Sat. Locally gusty
offshore flow will be possible night and morning hours Tue night
into Thu morning as well.
Daytime temps are forecast to remain about 4 to 8 deg below normal
on Wed, then warm considerably to near normal to slightly above
normal Thu, and to several degrees above normal for many areas Fri
before turning slightly cooler Sat. The warmest vlys and coastal
locations will reach the mid 60s Wed, and generally into the upper
60s to lower 70s Thu thru Sat.
At 0000Z Sunday, the marine layer at KLAX was 700 feet deep with
the top of the inversion at 1250 feet with a temperature of 17
High confidence in VFR conditions for all sites through the TAF
period...except for a 10% chance of lifr conditions at KPRB.
Weaker offshore winds are expected overnight through early Sunday
morning...mainly over Los Angeles and Ventura Counties. Gusty
winds over the L.A. mountains may cause turbulence through around
KLAX and KBUR...high confidence in VFR conditions through TAF
For the Outer Waters, high confidence in current forecast.
Northwest winds are at SCA level over the two northern outer
zones...and the southern outer zone will increase to SCA level by
3 AM Sunday morning. The gusty winds will likely persist through
late Tuesday night. A large, long period northwest swell will
bring hazardous (10+ foot) seas tonight through Monday.
For the Inner Waters, moderate to high confidence in current
forecast. For the waters north of Point Sal, SCA conditions are
expected to develop late tonight as 10+ foot seas move in and
northwest winds increase. SCA conditions are expected to last
through Monday night.
For the waters south of Point Conception, winds and seas are
expected to remain below SCA levels through Tuesday night. However
on Wednesday there is a good chance of SCA level northeast winds
.FIRE WEATHER...02/300 pm.
No changes expected for the current coverage of Red Flag Warnings,
which go through 6pm this evening for the Los Angeles and Ventura
County Valleys and Coasts. The Los Angeles County Mountains will
start at 6am this morning due to higher humidities and colder
conditions, but they will experience elevated risks with the
strong winds until then. The Ventura County Mountains will also
see elevated risks, but any Red Flag Conditions will be localized
and for a short duration.
Though much of the area has received around 1 inch of rain over
the last two weeks, the vegetation (fuels) remain receptive to
large fire growth under red flag weather conditions.
Those handling potential fire ignition sources must exercise
extra caution as extreme fire behavior and rapid fire growth is
expected if any fire were to be started. This includes those
lighting fires for warmth considering the cold conditions.
CA...Red Flag Warning in effect until 3 AM PST Sunday for zone
254. (See LAXRFWLOX).
PZ...Small Craft Advisory in effect from 3 AM to 9 PM PST Sunday
for zones 645-670-673-676. (See LAXMWWLOX).
.HAZARD POTENTIAL OUTLOOK...(TUE-SAT)
No significant hazards expected.