Area Forecast Discussion
Issued by NWS Los Angeles, CA
FXUS66 KLOX 022120
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
120 PM PST Fri Dec 2 2016
Moderate to strong Santa Ana winds will flow through portions of
Ventura and Los Angeles Counties through Saturday. Portions of
Santa Barbara County will have breezy winds. Temperatures will be
below normal for at least the next week but will warm slightly
during the next few days with Sunday as the warmest day.
Strong Santa Ana event in progress and expected to continue
through Saturday. No major changes to the forecast with the
afternoon update either short or long term. So far there has been
a stronger northerly component to the wind event versus east but
that is expected to change tonight as surface high pressure
continues to strengthen over the Great Basin. The NAM continues to
advertise stronger northeast winds around the 850mb level tonight
into early Sat than we had earlier today supporting the idea of a
stronger easterly component. So some areas that are more
susceptible to northerly winds may see slightly weaker winds
tonight while other areas will be stronger. Overall about the
same with peak gusts around 70 mph in the San Gabriels. So no
changes to the status of the wind headlines and hazards tonight
and Saturday. As many of the other Santa Ana wind events have done
this season dust from the Sand fire will continue to reduce
visibilities across the San Fernando Valley and Santa Monica
mountains. This will likely continue through the duration of this
Temps will warm up slightly Saturday as the cold advection
decreases. Best warmup will be in the mountains and deserts which
feel the impact of the cold advection the most and don`t have the
downslope heating effects to offset.
Warmer again Sunday with the ridge nudging in from the west. Most
coast/valley areas will be in the 70s. Still lingering northeast
winds through the morning as LAX-DAG gradient still well over -4mb
but fairly strong onshore trends should put an end to the Santa
Ana winds by afternoon.
The ridge weakens Monday as a trof moves into the Pac NW. Not
quite as much cooling as we thought a few days ago but most
coast/valley areas should be in the mid to upper 60s. Possibly
some marine lyr clouds returning to coastal LA County Monday
The trof deepens slightly Tuesday and will bring some additional
cooling to most areas. Increasing northwest flow with the trof
should limit any marine lyr cloudiness to LA County at most. Most
areas 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 1550Z, there was no marine inversion at KLAX.
Through the TAF period, VFR conditions will continue for all TAF
sites. Strong northeast flow through the period will create gusty
surface winds (especially across Ventura and Los Angeles
counties). Additionally, there will be areas of moderate LLWS and
KLAX...high confidence in VFR conditions through the period.
Moderate confidence in wind forecast as there is a 40% chance of
north to northeast winds exceeding 10 knots through this
afternoon and again Saturday morning. LLWS will be likely through
KBUR...high confidence in VFR conditions through the period.
Moderate confidence in wind forecast as gusty northerly winds will
erratically surface through this evening. LLWS and turbulence will
be issues through the TAF period.
For the Outer Waters, moderate to high confidence in current
forecast. Small Craft Advisory (SCA) level winds will continue
through tonight, before diminishing on Saturday (although SCA
level northeast winds may continue across the southern Outer
Waters through Saturday afternoon).
For the Inner Waters, moderate to high confidence in current
forecast. For the waters north of Point Sal, winds and seas will
remain below SCA levels through Saturday night. For Sunday through
Tuesday, there is a good chance of SCA level winds and seas. For
the waters south of Point Conception, Gale Force winds will
continue through this evening with SCA level northeast winds
continuing tonight and Saturday. For Sunday through Wednesday,
winds and seas are expected to remain below SCA levels (although
there is a chance of local SCA level gusts across the western half
of the Santa Barbara Channel in the afternoon/evening hours).
.FIRE WEATHER...02/900 am.
Strong upper level flow coupled with high pressure over the Great
Basin will continue to produce a strong Santa Ana wind event to
Los Angeles and Ventura Counties through Saturday. 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.
Over the coastal and valley areas (including the Santa Monica
Mountains), humidities will generally lower into the 10 to 15
percent range today and 8 to 12 percent range on Saturday.
Red flag conditions are expected this afternoon through Saturday
afternoon as a result. Red Flag Warnings are in effect for
coastal and valley areas of VTU and L.A. Counties through Sat
Over the mountains, the cold temperatures will keep relative
humidities generally above 20 percent today, but should lower
into the 10 to 20 percent range on Saturday. As a result, the
mountains will NOT have a Red Flag Warning today (though there is
an elevated risk with the strong winds) but the Los Angeles County
Mountains will be under a warning on Saturday. With weaker winds
and the same humidity issues, The Ventura County Mountains will
remain out of the Red Flag Warning.
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 from 2 AM to 8 AM PST Saturday for
zone 37. (See LAXNPWLOX).
Wind Advisory in effect until 2 PM PST Saturday for zones
40-41-87-547. (See LAXNPWLOX).
High Wind Warning in effect until 2 PM PST Saturday for zones
44>46-53-54-88. (See LAXNPWLOX).
Wind Advisory in effect until 6 PM PST this evening for zone
59. (See LAXNPWLOX).
Red Flag Warning in effect until 6 PM PST Saturday for zones
240-241-244>246-288-547-548. (See LAXRFWLOX).
Red Flag Warning in effect from 6 AM to 6 PM PST Saturday for
zone 254. (See LAXRFWLOX).
PZ...Gale Warning in effect until 9 PM PST this evening for zones
650-655. (See LAXMWWLOX).
Small Craft Advisory in effect until 3 AM PST Saturday for
zones 670-673. (See LAXMWWLOX).
Small Craft Advisory in effect until 2 PM PST Saturday for
zone 676. (See LAXMWWLOX).
.HAZARD POTENTIAL OUTLOOK...(MON-FRI)
No significant hazards expected.