592
FXUS66 KLOX 082234
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
234 PM PST Sun Dec 8 2024

.SYNOPSIS...08/119 PM.

Cooler weather today and Monday as light onshore flow returns as
well as areas of low clouds and locally dense fog. Then late
Monday into Wednesday a strong and possibly damaging Santa Ana
wind event is expected across parts of Los Angeles and Ventura
Counties. Fire weather concerns will be high with the winds and
low humidity.

&&

.SHORT TERM (TDY-WED)...08/200 PM.

...VERY STRONG SANTA WINDS EXPECTED LATER MONDAY INTO
WEDNESDAY...

Light onshore flow has returned to the area, leading to 10-20
degrees of cooling across all coast and valley areas. A low
stratus deck is looming across the coastal bight region, poised to
move onshore across most coastal areas this evening and overnight
with areas of dense fog. Low clouds will continue into the
morning hours but clear rapidly as the next Santa Ana wind event
begins around noon in the LA Mountains and mid to late afternoon
across the San Fernando, Santa Clarita, and interior Ventura
County Valleys.

A very strong Santa Ana wind is expected across portions of
LA/Ventura Counties later Monday into at least Tuesday, with some
lingering winds into Wednesday. Now that we`re within 48 hours of
the onset it`s within the window of our high res models and the
wind forecast looks quite similar to the last very strong event on
Nov 5-6 and highlighting most of the same areas that received
40-80 mph winds, namely the Santa Susana, San Gabriel, and western
Santa Monica mountains and even parts of the San Fernando, Santa
Clarita, and Ventura coast and valleys. Forecast gradients this
morning have come down slightly but still very strong with again
strong upper level support and good cold advection. Winds will
push well out over the coastal waters between Pt Dume to Ventura,
as well as off the OC coast, easily reaching the Channel Islands,
including Catalina, Anacapa, Santa Cruz, and San Miguel. The
combination of these strong winds and rapidly lowering humidity
into the single digits in some areas will lead to very dangerous
fire weather concerns. Given the lack of rain in these areas over
the last several months as well as several days of very low
humidities, any fire starts would be expected to have extremely
rapid spread.

On Wednesday much of the upper level support is gone but offshore
gradients are expected to be in the 5-6mb range so there will be
continued gusty winds and extremely high fire danger through at
least early afternoon.

With strong cold air advection high temperatures will be on the
cooler side, especially inland. Highs at lower elevations expected
to be around 70, and warmest at the coast. Then warming slightly
each day through Wednesday as the cold advection shifts east and
high pressure builds aloft. Overnight temperatures will be
modified in areas that are getting the Santa Ana winds. However,
outside those areas, with extremely low humidities, temperatures
will fall rapidly and well below freezing in some areas,
especially in the Antelope Valley where lows in the high teens are
possible in the colder areas. May need a freeze watch there with
the possibility of freezing pipes.

.LONG TERM (THU-SUN)...08/217 PM.

Still a lot of uncertainty with the specifics later next week as a
couple fast moving troughs pass through the state, though overall
weather conditions are expected to be very low impact. Onshore
flow will return Thursday as the first trough quickly moves
through. A few of the ensemble solutions show some light rain
across northern areas. After a brief period of weak ridging Friday
the next trough arrives along the west coast Friday night into
early Saturday. A few solutions show some very light rain as far
south as LA County, but most are quite a bit farther north and
event there amounts are mostly under a quarter inch. For most
areas, temperatures will be near normal (60s to low 70s) with no
significant winds.

&&

.AVIATION...08/1809Z.

At 1730Z at KLAX, the marine layer was 200 ft deep. The top of the
inversion was at 2450 ft with a temperature of 16 C.

Overall, moderate confidence in 18Z TAF Package. Highest
confidence in valley and desert TAFs, with low to moderate
confidence for coastal terminals. Timing of cig/vsby restrictions
may vary +/- 2 hours. Moderate confidence in VLIFR to LIFR conds
at times from 6z to 17z at coastal terminals.

KLAX...There is a 20 percent chance of VLIFR conds from 06 to
17z. Specifically, OVC002/380-548. (See LAXRFWLOX).
     Red Flag Warning in effect from 10 PM Monday to 10 PM PST
      Tuesday for zone 345. (See LAXRFWLOX).
     Red Flag Warning in effect from 2 PM Monday to 2 PM PST
      Wednesday for zones 354-355-362. (See LAXRFWLOX).
PZ...Small Craft Advisory in effect until 4 AM PST Monday for zone
      670. (See LAXMWWLOX).
     Small Craft Advisory in effect until 9 PM PST this evening
      for zone 673. (See LAXMWWLOX).
     Gale Watch in effect from Monday evening through Tuesday
      morning for zone 676. (See LAXMWWLOX).

&&

$$

PUBLIC...MW
AVIATION...Black
MARINE...Black/Hall
BEACHES...Hall
FIRE...Gomberg
SYNOPSIS...MW

weather.gov/losangeles

Experimental Graphical Hazardous Weather Outlook at:
https://www.weather.gov/erh/ghwo?wfo=lox