Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 190309
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
809 PM PDT Fri Oct 18 2019

.SYNOPSIS...18/806 PM.

Gusty northerly winds are expected especially over the Santa
Barbara South Coast and portions of Ventura and LA County
Saturday. By Saturday night, winds gradually shift northeast,
bringing stronger winds to most of LA County and the Ventura
mountains. Weak Santa Ana winds are expected Sunday night,
decreasing into Monday night.

&&

.SHORT TERM (FRI-MON)...18/808 PM.

Except for some patchy low clouds along and just off the Central
Coast, skies were clear across the forecast area this evening.
With low level flow turning more northeasterly  across SLO County
overnight, expect any low clouds to clear out. SBA-SMX pressure
gradients were -4 mb, slightly more strongly offshore than at this
time on Thu, and the gradients between SBA/BFL and LAX/BFL were
also slightly more strongly offshore. However, there was not as
much cold air advection or upper level wind support this evening,
so, overall do not expect winds to be quite as strong. Still,
expect solid wind advisory level winds across the mountains of SBA
County, the adjacent south coast of SBA County below passes and
canyons, and through the Interstate 5 Corridor. Widespread wind
gusts of 40 to 50 mph are expected, with local gusts to 55 to 60
mph near Montecito Hills and in the peaks around the I-5 Corridor.

***from previous discussion***

Pretty similar day Saturday as today overall with temps within a
few degrees of today. We`ll be transitioning to another strong
northerly wind event later Saturday into Sunday so we`ll likely
see winds increasing in strength in many areas by afternoon and
evening. Then overnight into Sunday the upper support from the
trough passage will kick in along with some cold air advection to
push wind speeds up to at least Thursday night`s levels and likely
a tad stronger. Models still showing a 6-7mb gradient from BFL
early Sunday morning which is 1-2mb stronger than what happened
earlier this morning. For this reason a high wind watch will be
issued for all the mountains, including the Santa Monicas, as well
as the Santa Clarita Valley Saturday night into Sunday morning.
Advisory level winds expected to develop in many other areas
including the LA/Ventura Valleys and even parts of the LA Coast,
especially from Malibu to the Hollywood Hills and down through the
south bay area. Highs Sunday expected to rise 3-6 degrees in most
areas.

Sunday afternoon into Monday we`ll be transitioning to a low
grade Santa Ana as the trough moves east and winds take on a more
easterly component. Upper support drops off and the air mass warms
as the ridge starts building in from the west but there will be
just enough surface gradient and winds up to 850 mb to maintain
gusty (though mostly sub-advisory level) Santa Ana winds across
LA/Ventura Counties as well as the Santa Lucia`s along the Central
Coast. Temps will be warming up quite a bit as well with highs
jumping up into the lower 90s for inland coastal areas and
valleys.

.LONG TERM (TUE-FRI)...18/143 PM.

Tuesday is expected to be the warmest day for coast/valleys as
gradients will start trending onshore later in the day into
Wednesday. Some light offshore breezes possible, mainly in the
mountains, but otherwise just hot and dry.

The ridge will start to shift back to the west as a trough drops
out of Canada and into the northern Rockies and Great Basin.
Gradients will turn onshore Wednesday into Thursday with high
temps dropping several degrees across coast/valleys, though still
a few degrees above normal. The Pacific ridge is expected to
expand east again over California and gradients will again turn
offshore following the trough passage through the Great Basin and
into the Plains. The GFS has fluctuated a fair amount on this but
the ECMWF has been consistent and now more ensemble members are
supporting at least an advisory level Santa Ana wind event Friday
into next weekend and likely very warm and dry.

&&

.AVIATION...19/0022Z.

At 2300Z at KLAX, there was no marine inversion.

VFR conditions with mainly clear skies expected across the
forecast area. Gusty N to NW winds will affect the mountains, the
Santa Clarita Valley and the south coast of SBA County through
Saturday, with associated local LLWS and moderate UDDF.

KLAX...High confidence in the 00Z TAF. VFR conds expected through
the period. There is a 10% chance of MVFR cigs between 12Z and
17Z Saturday morning. East winds will remain below 8 kts between
10-17Z tomorrow.

KBUR...High confidence in the 00Z TAF with VFR conds expected
through the period.

&&

.MARINE...18/748 PM.

Outer Waters...Moderate to high confidence. Gales are expected to
decrease to small craft advisory levels later tonight and then
continue through about Sunday night. Peak winds will be near 30
knots, with occasional gusts to 35 knots possible between San
Nicolas and Santa Rosa Islands on Saturday. Winds will turn more
northerly by Monday and diminish below SCA thresholds, then turn
back to the NW and remain near or below SCA through midweek.

Inner Waters N of Pt. Sal...Moderate to high confidence. SCA
level NW winds are likely through Saturday evening, although there
may be a lull during the morning hours. There is a 40% chance of
SCA level NW winds Sun afternoon and evening.

Santa Barbara Channel...Moderate confidence. SCA level W to NW
winds are expected across western portions through late tonight,
and for much of the time through Sunday evening. Occasional gusts
to 35 knots will be possible over the far western portion at
times through Sunday. NE winds early Monday may approach SCA
levels. Otherwise below SCA expected through Wednesday.

For the inner waters south of Pt. Mugu...Moderate confidence.
Winds and seas should remain below SCA levels through Wednesday.
There is a 30% chance of SCA level N to NE winds near shore from
Pt. Mugu to Santa Monica Sunday night and Monday morning.

&&

.BEACHES...18/751 PM.

Surf of 9 to 12 feet on exposed west-facing beaches of the
Central Coast will subside to 6 to 9 feet through Saturday
morning. South of Point Conception, the northwesterly component
of the swell means that less energy will make it to shore.
However, the west facing beaches of Ventura and Los Angeles
Counties could have surf of 3 to 5 feet through Sunday.

&&

.FIRE WEATHER...18/326 PM.

Northerly winds will persist across many portions of Southwest California
through Sunday, with peak gusts between 30 and 50 mph common. These winds will
affect the mountains, Santa Barbara south coast, the Santa Clarita Valley,
San Fernando Valley, Santa Monica Mountains and Central Coast. The strongest
northerly winds will be over the Santa Ynez Range and adjacent foothills, along
with the Tejon Pass Saturday night into Sunday, when isolated gusts of 60 to
70 mph are likely (especially near Montecito Hills and Whitaker Peak).
The Santa Barbara-Bakersfield gradient is expected to peak at around -5.5 mb
later tonight, increasing to around -6.5 mb on Saturday night. Minimum
humidities will generally range between 8 and 25 percent today through
Sunday. Recoveries at night will be moderate across the north facing mountains
with poor recoveries in the foothills and downslope areas. The combination of
moderate to locally strong sundowner winds combined with low humidities and
dry fuels has resulted in the Red Flag Warning for the Santa Barbara south
coast and mountains through Sunday evening. There will be widespread elevated
to brief critical fire weather conditions for many other portions of Southwest
California through Sunday due to the northerly winds and areas of low humidities.
Areas closest to critical conditions include the Los Angeles and
Ventura county mountains and Santa Clarita Valley.

The winds are  expected to shift to northeasterly Sunday night into Monday
when gusts between 25 and 40 mph will occur across wind prone areas of Los Angeles
and Ventura counties, strongest in the Los Angeles county mountains. The offshore
winds will further weaken on Tuesday morning. Minimum humidities will generally
range between 10 and 20 percent on Monday and Tuesday, while high temperatures
will climb to between 85 and 95 degrees. Another warm and potentially very dry Santa
Ana wind event will be possible by next Friday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory in effect until 8 AM PDT Saturday for
      zones 34-35. (See LAXCFWLOX).
     Wind Advisory in effect until 11 AM PDT Sunday for zone 39. (See LAXNPWLOX).
     Wind Advisory in effect from 6 PM Saturday to 11 AM PDT
      Sunday for zones 41-44-45-547. (See LAXNPWLOX).
     High Wind Watch in effect from Saturday evening through
      Sunday morning for zones 46-52>54-88. (See LAXNPWLOX).
     Wind Advisory in effect until 6 PM PDT Saturday for zones
      52-54. (See LAXNPWLOX).
     Wind Advisory in effect from 1 PM Saturday to 3 AM PDT Sunday
      for zone 59. (See LAXNPWLOX).
     Red Flag Warning in effect until 10 PM PDT Sunday for zones
      239-252. (See LAXRFWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT Saturday for
      zones 645-650. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Monday for zone
      670. (See LAXMWWLOX).
     Gale Warning in effect until 3 AM PDT Saturday for zones
      673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK (MON-FRI).

Elevated to briefly critical fire weather conditions possible
over Los Angeles and Ventura Counties Monday due to hot and dry
conditions and locally breezy Santa Ana winds. Critical fire
weather conditions possible later next week as Santa Ana winds
are expected to return.

&&

$$

PUBLIC...MW/DB
AVIATION...SMITH
MARINE...SMITH
BEACHES...Smith
FIRE...Gomberg
SYNOPSIS...Phillips

weather.gov/losangeles


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