Weather Service Report


849 
FXUS66 KLOX 011731
AFDLOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA 
1031 AM PDT SAT OCT 1 2016

.SYNOPSIS...
Two upper level troughs will bring increasingly cool and breezy
conditions to the region early this week, with temperatures down
to below normal levels today. It will remain cool on Monday, then
upper level ridging will produce a warming trend through mid week,
with above normal temperatures in most areas Wednesday through
Friday.

&&

.SHORT TERM...(TDY-MON)

Skies are mostly clear across the region this morning. Gusty
winds across southern Santa Barbara County have diminished to less
than 20 mph in most areas. By and large temperatures are down 3 to
5 degrees this morning except for those areas of the Central Coast
which were cooled by fog and low stratus yesterday morning. Pismo
Beach is up 14 degrees from its foggy start yesterday.

*** From Previous Discussion ***

Heights will continue to fall across the region today as the
upper trough extending southward from an upper low off the Oregon
coast pushes toward the region. With falling heights, cooling at
850 mb and 950 mb and increasing W-E onshore gradients, expect
several degrees of cooling in most areas today. Still, the warmest
locations in the valleys of L.A. and VTU Counties could have highs
close to 90 degrees today, but most valley locations will have
highs in the 80s. Good N-S gradients will likely produce some
warming in coastal areas of SLO and SBA Counties today. Also,
expect some gusty northwest winds this afternoon on the Central
Coast, in the SLO County Valleys, and across the south coast of
SBA County from Refugio westward. At this point, expect winds to
remain just below advisory levels, but they will be close, and it
would not be a surprise if advisories are needed in some areas.

Gusty northwest to north winds will affect the Santa Ynez Range
and the adjacent south coast of SBA County below passes and
canyons this evening and early tonight. It could be a marginal
wind advisory event tonight.

The upper low off the coast of Oregon will be replaced by a stronger
elongated upper low dropping southward through the eastern Pacific.
This upper low will be located just off the Oregon coast early
Sunday morning, with a rather sharp trough extending southward.
The WRF suggests that low clouds may be patchy in nature north of
Pt Conception, but it does show an eddy circulation developing
tonight across the Santa Monica Basin, with low clouds in coastal
sections of L.A. County, spreading into coastal sections of VTU
County late tonight. Also, with the marine layer deepening, some
clouds will probably push into at least the San Gabriel Valley
late tonight. Increasingly moist and cyclonic low level flow
across L.A. and VTU Counties could allow for some drizzle late
tonight/Sunday morning.

The trough axis will swing across CA during the day Sunday. The
southern end of rain associated with a frontal system could get
rather close to SLO County on Sunday. The WRF shows clouds
lingering at the beaches of L.A. and VTU Counties well into the
afternoon on Sunday. It will be much cooler across the entire
region on Sunday, with max temps well below normal in most areas.

Increasing w to nw flow aloft and decent subsidence spreading over
the region late Sunday should bring gusty to possibly advisory
levels west winds to the Antelope Valley and northwest winds to
the Central Coast Sunday afternoon and evening. Expect a rather
strong northwest to north wind event across the Santa Ynez Range
and the adjacent south coast of SBA County Sunday evening, and
wind advisories will likely be needed. Gusty nw to n winds will
develop across the Interstate 5 corridor Sunday night, and they
may also reach advisory levels. The north winds will spread into
the western and northern portions of the L.A. County valleys, the
Santa Monicas, and coastal sections of L.A. County below passes
and canyons from Malibu to the Hollywood Hills late Sunday night
into Mon morning. Moist upslope northerly flow could bring a few
showers to the northern slopes of the VTU and possibly far
northwestern L.A. County mountains Sunday night/Mon morning, with
snow showers above 6500 feet or so. The stratus pattern will
likely be patchy in nature as the marine inversion weakens. Monday
will be a rather chills day across most of the region, with max
temps well below normal. 



.LONG TERM...(TUE-FRI)

The upper trough will move eastward Tue and Wed and an upper high
will build into the region. Weak offshore flow should keep skies
clear. There will a significant warming trend Tue and Wed, with
temps back to above normal levels by Wed, then similar temps are
expected on Thu and Fri.



&&

.AVIATION...01/1800Z...

A mid/upper level trough of low pressure upstream will move over
the area. Upper level strong southwest winds will become moderate
to strong west-southwest by 02/00z while mid level light to
moderate southwest winds become moderate west after 02/20z over
the area. Weak onshore pressure gradient through 02/02z and
moderate after 02/20z otherwise weak to moderate northerly
gradient. Base of a weak capping marine inversion was
approximately .8kft this morning with isolated cloud field over
the San Pedro Basin this morning. The inversion base will differ
little and cloud field may become scattered to broken over the
bight Sunday morning.

Marine layer at LAX at 1500Z is 810 feet deep and the inversion
top is at 1533 feet with a temp of 21.2 degrees C.

KLAX...Chance cigs 006 and vsby 4sm br between 02/12-02/16z.

KBUR...Virtually certain current sky/vsby conditions will
persist.

virtually certain - 95-100%
very likely       - 80-95%
likely            - 60-80%
chance            - 30-60%
very unlikely     - 20% or less

&&

.MARINE...01/900 AM...

Northwest wind with small craft advisory conditions will continue from
Piedras Blancas to San Nicolas Island through next week Tuesday. Occasional
gale force gusts are expected each afternoon through Sunday. The
gales force gusts may become frequent south of the Northern
Channel Islands Sunday night through Monday and a gale watch is
in effect. Northwest winds will likely fill in over portions of
the inner basins each afternoon through Monday. There will likely
be a lull in the wind for several hours after sunrise through
Tuesday but small craft advisory for hazardous sea conditions will
likely exist.


&&

.FIRE WEATHER...

01/930 AM.
Gusty sundowner winds with elevated fire danger will impact the
Santa Barbara South Coast and Santa Ynez mountains during the late
afternoon and nighttime hours through Tuesday night. For tonight, 
wind gusts of 30 to 40 mph will mostly be confined to the coastal
and foothill areas west of Goleta (especially in the hills above
Refugio). On Sunday night and Monday night, the winds are
expected to be stronger (peaking between 40 and 50 mph in the
foothills) and more widespread due to increased upper level wind
and thermal support. On Sunday night, the Santa Barbara-Santa
Maria gradient is expected to peak around -4.5 mb. It appears that
humidities will remain well above critical levels during the next
few days, so no Red Flag Warnings are planned at this
time, however large wind driven fires will be possible in moderate
humidity regimes due to the very dry fuels.

Other target areas of stronger winds and elevated fire danger on
Sunday and Monday will be the Antelope Valley and Interstate 5
Corridor, where gusts between 35 and 50 mph will be common. Sunday
night through Monday night, locally gusty northerly winds are
also expected to impact the Santa Clarita and San Fernando
valleys, Santa Monica Mountains, and Hollywood Hills. These gusty
northerly winds with lowering humidities on Monday will also bring
elevated fire danger to these areas as well. 

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect until 3 AM PDT Sunday For zone
      645. (See LAXMWWLOX).
     Small Craft Advisory in effect until 6 PM PDT Sunday For
      zones 670-673-676. (See LAXMWWLOX).
     Gale Watch in effect from Sunday evening through Monday
      evening For zones 673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...JLD
FIRE...Gomberg
AVIATION...30
MARINE...30
SYNOPSIS...Sweet

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