Wildfire in California, November 8 to 22, 2018

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
152 PM PST Thu Nov 8 2018

.SYNOPSIS...08/1124 AM.

Offshore winds will continue to increase this evening in Ventura
and Los Angeles counties. Winds will begin to relax Friday night,
only to increase again by Sunday morning. Low temperatures will
fall to or below freezing in both the Antelope Valley and
interior areas of San Luis Obispo county from tonight through
Sunday morning. High temperatures will remain above normal
through the entire period.

&&

.SHORT TERM (TDY-SUN)...08/105 PM.

Santa Ana event has arrived though the 3000'+ marine layer this
morning has delayed the onset in some areas, particularly coastal
LA County and the eastern San Fernando Valley. Really no change
from previous thinking in terms of the strength and timing of the
peak winds, which still looks to be overnight tonight into early
Friday. Will keep all wind advisories and warnings in place
through Friday with an earlier cut off time for the coast as
onshore trends take hold there.

Weekend forecast about the same as well. Gradients turn weakly
onshore Saturday into early Sunday before reversing again as
another trough dropping through the Great Basin will initiate
pressure rises over the interior and another push of Santa Ana
winds late Sunday into Monday. This second event is still looking
weaker than this one but probably still advisory level winds in
the usual favored areas of LA/Ventura counties. And again still
very dry so it's quite possible critical fire weather conditions
will return.

In some wind protected locations overnight temps will drop below
freezing such as interior SLO County and the Antelope Valley.
Coldest temps expected to be Saturday morning where lows near 20
are possible in the AV and mid to upper 20s across interior SLO.
With another burst of offshore flow coming next week expect chilly
overnight temps to continue in these same areas.

.LONG TERM (MON-THU)...08/112 PM.

The peak of the second Santa Ana event is expected to be Monday
morning. The ridge aloft will likely result in this being a
somewhat warmer Santa Ana than the current one but still some
uncertainty on how warm. Thicknesses actually remain fairly flat
through the period but lower level temps rise a few degrees
through mid week so odds favor a warm period but not threatening
any records. Some cooling expected by Thu for coast/valleys as
gradients start trending (though not actually turning) onshore.

&&

.AVIATION...08/1716Z.

At 16Z, the marine layer depth was around 2500 feet deep at KLAX.
The top of the inversion was near 4600 feet with a temperature of
about 16 degrees Celsius.

Moderate confidence in the current forecast through 20Z, then
increasing to moderate to high confidence thereafter. VFR
conditions will develop throughout the remainder of this morning.
Periods of moderate to strong wind shear and turbulence is
possible across Los Angeles and Ventura County terminals through
16Z Friday.

KLAX...VFR conditions will become prevalent through 18Z. There is
a 50 percent chance of moderate to strong low-level wind shear
and turbulence between 02Z and 14Z. There is a 30 percent chance
of east winds greater than 7 knots between 05Z and 12Z.

KBUR...VFR conditions will become prevalent through 18Z. There is
a 60 percent chance of strong low-level wind shear and turbulence
between 02Z and 14Z.

&&

.MARINE...08/1253 PM.

Small Craft Advisory level northeast winds and short-period seas
will continue to develop across across the waters south of Point
Conception this evening, then linger into Friday. The winds will
be strongest nearshore between Rincon Point and Santa Monica and
south of the Palos Verdes Peninsula.

Strong northeast winds across the coastal waters can result in
gusty winds and hazardous swell activity in the exposed east-facing
harbors of the Channel Islands, including Avalon Harbor on
Catalina Island. If seeking safe harbor during these gusty winds,
Avalon Harbor should not be considered safe harbor.

Otherwise and elsewhere, conditions will remain below advisory
criteria through Sunday.

Gusty northeast winds could redevelop across the coastal waters
south of Point Conception Sunday. There is a 30 percent chance
that a Small Craft Advisory will be needed between Sunday and
Monday.

&&

.FIRE WEATHER...08/152 PM.

An extended period of offshore flow will bring elevated to
critical fire weather conditions to the area today through the
end of next week. A moderate to strong Santa Ana wind event will
continue today through Friday across Ventura and Los Angeles
counties. Northeast winds will increase this afternoon and
evening, peak in strength tonight and Friday morning (gusts 50-70
mph) then diminish during the day on Friday. Very dry air will
move into the area with humidity dropping into the single digits
this afternoon and Friday with little or no recovery tonight. So,
widespread critical fire weather conditions are expected across
Ventura and Los Angeles counties today through Friday evening and
a RED FLAG WARNING remains in effect.

For San Luis Obispo and Santa Barbara counties, the offshore winds
will be much weaker. However, there still will likely be wind
gusts between 25 and 35 mph across the mountains and foothills
today through Friday. With humidity dropping into the single
digits (with poor overnight recovery), elevated to locally
critical fire weather conditions can be expected through Friday.

On Saturday, the offshore winds will abate, but RED FLAG
conditions may still continue across the mountains. Elevated fire
weather conditions can be expected elsewhere.

For Sunday into the first half of next week, another round of
Santa Ana winds is expected, although the strength of the winds
will be less than the current event. However, very dry atmospheric
and vegetation will remain. So, there is a good chance of
widespread critical fire weather conditions Sunday through
Tuesday.

Considering the wind speeds, extremely dry vegetation and fuels,
and the long duration of the event, this is a dangerous situation.
The public needs to be reminded to be very careful with any
potential fire ignition sources. Large fires have been started by
things such as discarded cigarettes, dragging tow chains, metallic
weed whackers, campfires, and welding equipment.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Freeze Warning in effect from midnight tonight to 9 AM PST
      Sunday for zone 37. (See LAXNPWLOX).
     Wind Advisory in effect until 3 PM PST Friday for zones
      40-41. (See LAXNPWLOX).
     Wind Advisory in effect until 6 PM PST Friday for zones
      44-45-53-88-547. (See LAXNPWLOX).
     Wind Advisory in effect until 6 PM PST this evening for zones
      46-54. (See LAXNPWLOX).
     High Wind Warning in effect from 6 PM this evening to 6 PM
      PST Friday for zones 46-54. (See LAXNPWLOX).
     Freeze Warning in effect from midnight tonight to 9 AM PST
      Friday for zone 59. (See LAXNPWLOX).
     Hard Freeze Watch in effect from late Friday night through
      Sunday morning for zone 59. (See LAXNPWLOX).
     Red Flag Warning in effect until 10 PM PST Friday for zones
      240-241-244>246-253-254-288-547-548. (See LAXRFWLOX).
PZ...Small Craft Advisory in effect until 3 PM PST Friday for
      zones 650-655. (See LAXMWWLOX).
     Small Craft Advisory in effect from 5 PM this afternoon to 3
      PM PST Friday for zone 676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK (SUN-THU).

Elevated to critical fire weather conditions expected through the
period with gusty Santa Ana winds at times and very low
humidities. Sub-freezing temperatures expected Sunday morning in
the Antelope Valley and interior SLO County and possibly through
the middle of next week as well.

&&

PUBLIC...MW
AVIATION...Hall
MARINE...Hall
FIRE...Thompson
SYNOPSIS...TF

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