663 
FXUS66 KLOX 120333
AFDLOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA 
833 PM PDT Wed Oct 11 2017

.SYNOPSIS...
Coastal low clouds and slightly cooler temperatures overall will 
return to the region through Thursday. Gusty northerly winds will
develop across portions of the forecast area by Friday with gusty
offshore flow likely returning for the weekend. This will bring 
warmer temperatures into early next week for coast and coastal
valleys. Another low may approach by Tuesday for a cooling trend 
and increasing coastal low clouds into midweek.

&&

.SHORT TERM...(WED-SAT)

There were a few low clouds along the L.A. County coast this 
evening, otherwise mostly clear skies prevailed across the forecast 
area. A weak eddy is expected to develop over the SoCal bight 
overnight and help to expand low clouds over the Bight and into the 
L.A. County coast. Otherwise, offshore flow will increase over 
SLO/SBA Counties overnight with the low clouds remaining s of Point 
Conception. This will result in mostly clear skies over much of the 
forecast area thru the night. Locally gusty nw to n winds can also 
be expected below and thru the passes and canyons of SBA County S 
coast and mtns thru the night.

Broad upper level troffiness will persist over srn CA tonight thru 
Fri, then upper level ridging will start to move into the area later 
Fri night and Sat.

Some low clouds are expected over the L.A. County coastal areas Thu 
night into Fri morning, and possibly Fri night and early Sat. 
Otherwise, mostly clear skies will prevail over the forecast area 
thru Sat.

Offshore flow will prevail over SLO/SBA Counties night and morning 
hours thru Sat. Increasing northerly gradients should also bring 
gusty northwest to north winds each evening to the SBA County S 
coast and mtns thru Fri night, with some advisory level gusts 
possible below and thru the passes and canyons mainly W of Goleta. 
Offshore gradients will increase Fri night and Sat as well, with 
gusty NW winds possible in the mtns along the I-5 Corridor Fri 
night, then shift N and spread to the eastern VTU County vlys, Santa 
Clarita Vly, San Fernando Vly and Santa Monica mtns later Fri night 
into Sat morning. It looks like the winds will shift to the NE and 
increase Sat afternoon and extend to the coastal areas of VTU County 
and the L.A. County coast from Malibu to the Hollywood Hills. 
Advisory level wind gusts will be possible at times during the 
period.

Temps across the forecast area are expected to be near normal to 
slightly below normal on Thu, then warm to near normal to slightly 
above normal for many areas Fri and Sat. Highs in the warmest vlys 
and inland coastal areas should reach the mid 70s to around 80 on 
Thu, low to mid 80s Fri, and mid to upper 80s on Sat. 

***FROM PREVIOUS DISCUSSION***

.LONG TERM...(SUN-WED)

High pressure will build over the area through Monday then break
down Tuesday as a new trough pushes onshore over the Pac NW.
Northerly gradients will weaken Sunday but east/west gradients
will peak on Sunday before decreasing Monday and turn onshore 
Tue/Wed. Temperatures will likely peak in most areas Sunday with
the combination of the high pressure aloft and offshore flow, then
some cooling for coast/valleys Monday as gradients trend onshore
and an earlier sea breeze develops. Cooling will spread all the
way inland Tue/Wed as westerly flow aloft returns and onshore flow
increases. Temperatures will drop back to normal Tue and possibly
a tad below normal Wed. Will probably see some low clouds 
returning to coastal areas at some point around mid week.

&&

.AVIATION...11/2345Z...

At 2259Z, the marine inversion at KLAX was 1200 feet deep. The top 
of the inversion was at 2400 feet with a temperature of 20 degrees 
Celsius.

Generally hi confidence in the 00Z TAFs, except moderate confidence 
at KSMO, KLAX and KLGB. There will be VFR conditions likely through 
the TAF period at most airfields. However, for KSMO, KLAX and KLGB, 
it looks like IFR/MVFR cigs will develop later tonight and persist 
thru late Thu morning, except until early Thu afternoon at KLGB. The 
timing of the onset and dissipation of the low clouds may be off +/- 
an hour or two. Otherwise, VFR conditions will prevail at these 
airfields thru Thu afternoon. Gusty sw winds will continue through 
early this evening at KWJF and KPMD.

KLAX...Moderate confidence overall in the 00Z TAF. IFR/MVFR cigs 
will develop later tonight and persist thru late Thu morning. The 
timing of the onset and dissipation of the low clouds may be off +/- 
an hour or two. Otherwise, VFR conditions will prevail thru Thu 
evening.

KBUR...Generally hi confidence in the 00Z TAF with VFR conditions 
likely through Thu afternoon.

&&

.MARINE...11/800 PM.

Generally good confidence in the current forecast. Gale force 
winds will prevail in zone 670 tonight through Thursday evening, 
with Small Craft Advisory (SCA) winds tonight increasing to Gale 
force in zone 673 Thursday morning and persisting through Thursday
evening. The winds will diminish to SCA levels and continue into
Sat. SCA winds will spread into zone 676 on Thu and continue into
Sat as well.

SCA level winds should affect zone 650 Thu night and Fri morning,
otherwise advisories/warnings are not expected over the inner
waters through Sat.

&&

.FIRE WEATHER...11/300 PM...

For tonight through Saturday morning, an increasing northerly 
surface pressure gradient will generate gusty north winds across 
the area. The northerly winds will be on the weak side tonight 
with gusts around 30 mph across southern Santa Barbara county as 
well as the Interstate 5 corridor. In these areas, relative 
humidity will exhibit decent recoveries tonight. However across 
northern San Luis Obispo county, drier air will begin moving in 
tonight. So with the expected northerly winds and drier air, there
will be elevated fire weather conditions across northwest San 
Luis Obispo county tonight and Thursday morning.

During the day on Thursday, the northerly winds will increase and
remain at moderate levels through Saturday morning. Wind gusts
between 35 and 45 mph are expected across the Santa Ynez range 
and adjacent coastal foothills as well as the Interstate 5 corridor
Thursday evening through Saturday morning. As the winds increase, 
very dry air will filter into the area with widespread relative
humidity in the teens and single digits expected Thursday and Friday
afternoon with poor recovery overnight. This combination of gusty 
winds and very low relative humidity will result in an extended period 
of critical fire weather conditions and a Red Flag Warning has been
issued for these areas Thursday evening through Saturday morning. There
is a possibility that critical fire weather conditions could move into 
the Santa Clarita and San Fernando Valleys as well as the Santa Monica
Mountains. So, a Fire Weather Watch has been issued for these areas 
Thursday evening through Saturday morning.

By Saturday morning, the winds turn to the northeast and a weak to 
moderate Santa Ana wind event is expected Saturday and Sunday. Very
dry air will remain in place this weekend. So, there will be the 
possibility of critical fire weather conditions across Ventura and
Los Angeles counties.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Red Flag Warning in effect from 8 PM Thursday to 10 AM PDT
      Saturday for zones 239-252>254. (See LAXRFWLOX).
     Fire Weather Watch in effect from Thursday evening through
      Saturday morning for zones 246-288-547. (See LAXRFWLOX).
PZ...Gale Warning in effect until 9 PM PDT Thursday for zone 670.
     (See LAXMWWLOX).
     Small Craft Advisory in effect until 9 AM PDT Thursday for
      zone 673. (See LAXMWWLOX).
     Gale Warning in effect from 9 AM to 9 PM PDT Thursday for
      zone 673. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK...(SAT-WED)
Gusty northerly winds will bring the potential for critical fire 
weather conditions Saturday, especially the mountains and Santa 
Barbara South Coast. Weak to moderate Santa Ana winds could bring 
additional fire weather concerns to LA/Ventura Counties Sunday.

&&

$$

PUBLIC...Sirard/MW
AVIATION...Sirard
MARINE...Sirard
FIRE...Thompson
SYNOPSIS...Sirard

weather.gov/losangeles