Area Forecast Discussion
Issued by NWS Los Angeles, CA
FXUS66 KLOX 031403
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
603 AM PST Sat Dec 3 2016
Strong Santa Ana winds will continue this morning in some areas
of Los Angeles and Ventura counties before diminishing through
this afternoon. High pressure aloft will build in from the Eastern
Pacific supporting gradual warming on Sunday. A deepening trough
of low pressure will likely bring cooler conditions with some
coastal areas getting low clouds. Locally gusty north winds
shifting northeast by the middle of next week.
Strong and damaging winds continued last evening through early
this morning with High Wind Warning Gusts between 58 and 83 mph
across the San Gabriel Mtns and adjacent foothills including
La Canada and Newhall Pass. Winds overall remained quite gusty in
the usual wind prone areas of a Santa Ana for LA/VTU counties.
Latest Water Vapor Imagery indicated a closed upper low just
entering Old Mexico around 240 miles s-se of Yuma AZ. Winds are
expected to remain quite strong over LA/VTU counties this
morning. We will lose some of the upper level support as the upper
low continues to move farther south and east over Mexico. However the
surface gradients between LAX-DAG are trending stronger offshore
and should be around -5 mb this morning. High wind warnings will
remain in effect for the same areas today through mid afternoon.
This includes the mountains of LA/VTU including the Santa Monica
Mtns as well as the Ventura County Valleys and Santa Clarita
Valley. wind advisories will also remain in effect for the same
areas as yesterday as well including Catalina Island where gusty
ofshore winds should continue to bring choppy seas into the harbor
through this morning. Strongest winds will occur through late
this morning. Winds will then begin to diminish some late this
afternoon through this evening. There will continue to be
critical fire danger due to the strong winds and lower relative
humidities through this afternoon as red flag warnings will stay
in effect through early this evening. Strongest winds will occur
through late this morning then diminish some through the afternoon
hours. High temps will warm across the entire forecast area with
best warming in the mountains and valleys. as much as 10 to 14
degrees of warming in some mountain locations with most areas up 4
to 6 degrees.
For Sunday, expect additional warming as an upper lvl ridge will
build in from the Eastern Pac while the upper low continues push
further into Mexico. The offshore flow will be much weaker in the
mornnig...then turn onshore by Sunday afternoon for coast and
valleys. Best warming will be across inland areas while coastal
areas should be only a degree or two warmer. Highs will be in the
upper 60s along the coast to the lower to mid 70s for inland
coastal areas and valleys. By Monday the upper ridge will begin to
flatten out as another upper level trough begins to slide down the
Pac NW into the Great Basin. Yes, another inside slider. Some
northerly flow will develop as the trough moves through. There
will be enough moisture across the San Joaquin Valley that some
moisture will bank up against the nrn slopes of the mountains
sunday night into Monday. Also, and eddy will develop across the
SOCal bight and some low clouds have been reintroduced into the
forecast for the LA/VTU coastal areas. There is a chance that low
clouds could remain offshore, but most models are showing this
feature occurring. With the continued onshore flow and marine
layer influence...expect widespread cooling. 2-6 degrees for coast
and valleys, with around 4-8 degrees of cooling for interior areas
and lower mountain elevations.
The trof will continue to deepen slightly Tuesday and will bring
some additional cooling to most areas. Increasing northwest across
the outer waters should help an eddy develop over the SOCal bight
allowing for some low clouds to develop across the LA County coast
and possibly as far north as Oxnard. But NW winds across SBA
County should keep low clouds to the south. Most areas will be down
about 5 degrees from Monday. Then turning warmer Wed-Fri as weak
ridging and offshore flow return. The tail end of a cold front may
just brush the Central Coast Friday afternoon but precip should
remain north of SLO County.
At 1115Z, there was no marine inversion present at KLAX.
Clear skies with VFR conds expected across the entire forecast
area through the period. There will be strong and gusty ne winds
across much of L.A. and VTU Counties through early afternoon, with
areas of LLWS and mdt to stg UDDF.
KLAX...High confidence in the 12Z TAF with VFR conditions
expected through the period. There is a 20 percent chance of N
winds of 10 to 15 knots through 19z this morning. There will
likely be some LLWS near the airport this morning.
KBUR...High confidence in the 12Z TAF with VFR conditions
expected through the period. There is a 20 percent chance of N to
NE winds sustained at or above 20 knots or gusts at or above 30 kt
through 19z this morning. There will likely be some LLWS near the
airport this morning.
High confidence in SCA level NE winds across the southern inner
waters, eastern SBA Channel and eastern portions of the southern
Outer Waters through early this afternoon. Seas will be rough and
choppy with a short period. Good confidence that conds will drop
below SCA levels by mid afternoon.
Across the northern two thirds of the outer waters, winds
will be close to SCA levels through Sun but will probably remain
just below. There is a 20 percent chance that a SCA will be needed
for these late areas this afternoon and evening. Seas will likely
increase to SCA thresholds across the outer waters on Sunday, then
both seas and winds will likely meet SCA thresholds there Sun
night through at least late Tue. A SCA for hazardous seas will
likely be needed across the nrn inner waters Sun through Mon.
.FIRE WEATHER...03/600 am.
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...Freeze Warning in effect until 8 AM PST this morning for zone
37. (See LAXNPWLOX).
Wind Advisory in effect until 2 PM PST this afternoon for
zones 40-41-87-547. (See LAXNPWLOX).
High Wind Warning in effect until 2 PM PST this afternoon for
zones 44>46-53-54-88. (See LAXNPWLOX).
Red Flag Warning in effect until 6 PM PST this evening for
zones 240-241-244>246-254-288-547-548. (See LAXRFWLOX).
PZ...Small Craft Advisory in effect until 2 PM PST this afternoon
for zones 650-655-676. (See LAXMWWLOX).
.HAZARD POTENTIAL OUTLOOK...(MON-FRI)
No significant hazards expected.