High Wind in California, December 7 to 10, 2023

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
953 PM PST Thu Dec 7 2023

.SYNOPSIS...07/948 PM.

Gusty northerly winds will continue across portions of the area
overnight into Friday, with the strongest winds in the mountains
tonight. On Friday evening winds will shift into a Santa Ana wind
pattern, and continue into early next week with warming
temperatures.

&&

.SHORT TERM (THU-SUN)...07/850 PM.

Offshore N-S gradients continued to increase across the forecast
area this evening. NW to N winds were increasing across southern
SA County and in the mountains from SBA County to the I-5 Corridor.
So far, winds were mostly in the advisory level category, but
with some additional increase in strength expected, locations
under the High Wind Warnings (the eastern Santa Ynez mtns, the
interior mtns of SBA County, the Ventura County mountains and the
I-5 Corridor) should have some gusts to between 60 and 65 mph
overnight. Advisory level winds have spread into the Santa Clarita
Valley, the western San Fernando Valley, the eastern Santa Monica
range and the Malibu area, and may push into West Los Angeles for
a few hours tonight. So, overall the wind forecast was working
out pretty well.

As expected, there was significant cooling across the region
today, with max temps down 6 to 10 degrees in many areas, and
more than 15 degrees in a few locations. Winds will begin to
subside very late tonight through mid morning Friday. Skies will
generally be mostly clear overnight, though some patchy low clouds
may affect southern portions of the Central Coast and the Santa
Ynez Valley as northerly winds push up again the Santa Ynez Range.

***from previous discussion***

Winds expected to lighten quite a bit Friday during the daytime
as upper support and gradients weaken. Then, following the passage
of another upper low through the Great Basin winds will shift to
the northeast starting our next Santa Ana wind event for
LA/Ventura Counties. The latest NAM model shows a -9mb LAX-DAG
gradient which is at the very high end of climatology so this
event has the potential for generating wind speeds not often seen
with Santa Anas. Latest model projections are indicating about a
60% chance of winds higher than 50 mph in Camarillo late Friday
night into Saturday morning and even about a 20% chance of 60 mph
winds there. Likely higher chances of those wind speeds occurring
farther inland across Ventura County, including Simi Valley and
parts of Thousand Oaks, as well the western Santa Monica mountains
and areas like Porter Ranch in the northern San Fernando Valley,
and the Santa Clarita Valley.

Offshore gradients remain quite strong into Sunday, though
somewhat less upper support by then. Still a very windy day across
LA/Ventura Counties, particularly in the morning.

Temperatures will be warming through Sunday, though with the
system entraining colder air from the Great Basin the source air,
even with the strong downsloping flow warming the air as it
descends and compresses, highs should stay mostly in the 70s at
lower elevations. And likely warmest at the coast. Overnight lows
will get chilly in those areas that are protected from the winds,
including the Ojai Valley and Antelope Valley. Elsewhere, winds
will keep the air mixed with more moderate overnight temps.

.LONG TERM (MON-THU)...07/159 PM.

Ensembles remain in good alignment with the deterministic runs
which show high pressure keeping a stronghold on most of
California through at least Friday. There is a very weak trough
that comes through late Sunday into Monday and then a follow up
trough Tuesday which sets the stage for what looks like another
Santa Ana wind event later Tuesday into Wednesday. At this point
this one doesn't look as strong as the weekend event but could see
some low end advisory level winds across parts of LA/Ventura
Counties. High temperatures expected to remain mostly in the 70s
next week at lower elevations, except slightly cooler at the
beaches.

&&

.AVIATION...08/0546Z.

At 0311Z at KLAX, there was no marine layer or inversion.

Low to moderate confidence in the 06Z TAFs. Gusty N winds will be
possible for many locations through tonight with some LLWS and
turbulence, most notably along southern Santa Barbara County and
western L.A. County. There is a chance of IFR CIGs at KPRB,
otherwise VFR conditions are forecast across the area. However
there is a 10-20 percent chance of IFR conds along the Central
Coast overnight.

KLAX...Low confidence in the 06Z TAF due to uncertainty in the
winds. There is a 30 percent chance of north cross winds gusting
to 20 knots between 08Z and 12Z, and a 40% chance of an east wind
component of 6 kts after 12Z. Otherwise, VFR conds expected
through the period.

KBUR...Low confidence in the 06Z TAF due to uncertainty in the
winds. There is a 200% chance of north wind gusts up to 20 kt
between 08Z through 12Z.

&&

.MARINE...07/821 PM.

For the Outer Waters and all waters along the Central Coast,
Small Craft Advisory (SCA) level seas of 10 to 14 feet will begin to
subside Friday night into Saturday. The GALE WARNING remains in
effect for zones PZZ673 and PZZ676, with a 60% chance of Gale
Force gusts lingering through Friday evening. Friday night into
Saturday afternoon, there is a 60% chance of N-NE SCA level winds
across the waters south of the Channel Islands, and a 30% of N-NE
SCA winds across the other portions of the waters into mid-
Saturday morning. Sunday afternoon through Tuesday morning, there
is a 30-40% chance of SCA northerly winds.

For the Inner Waters south of Point Conception, NW SCA level
winds expected to persist over the western portions of all the
southern inner waters into Friday morning. Winds will shift to the
north to NE over the day Friday, and strengthen to SCA levels
across the waters from Ventura to Santa Monica and out past
Anacapa Island during the afternoon and overnight hours. In this
area there is a 40-50% chance of Gale Force winds nearshore.
There is a 30-50% chance of SCA winds extending from Orange
County out to Catalina Island with gusts of 25 kt and wind waves
of 2 to 4 feet possible Friday night into Saturday morning. There
is a 20% chance of lighter SCA winds continuing through Sunday
morning. By Sunday afternoon, conds will likely remain below SCA
levels.

&&

.BEACHES...07/152 PM.

Long period NW swell (15-18 seconds) will affect the coastal
waters through Friday. Expect 9 to 13 feet for Central Coast
beaches, 5 to 8 feet with local sets to 9 feet for Ventura County
beaches, and elevated surf of 4 to 6 feet for LA County beaches.
Extended the High Surf Advisory and Beach Hazards Statement
through Friday afternoon. Surf heights will be highest across west
and northwest facing beaches. Due to low astronomical tides, any
coastal flooding will be very minimal.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect until 10 AM PST Friday for zones
      88-362-370-372-379. (See LAXNPWLOX).
     High Wind Watch in effect from Friday evening through
      Saturday afternoon for zones
      88-358-362-369-371-372-374-375-379. (See LAXNPWLOX).
     High Surf Advisory in effect until 4 PM PST Friday for zones
      340-346-354. (See LAXCFWLOX).
     Wind Advisory in effect until 3 AM PST Friday for zones
      346>351-356-366-367-381. (See LAXNPWLOX).
     High Wind Warning in effect until 6 AM PST Friday for zones
      352-353-376-377. (See LAXNPWLOX).
     High Wind Watch in effect from late Friday night through
      Saturday afternoon for zones 354-355. (See LAXNPWLOX).
     Beach Hazards Statement in effect through Friday afternoon
      for zones 362-366. (See LAXCFWLOX).
     High Wind Warning in effect until 10 AM PST Friday for zone
      378. (See LAXNPWLOX).
     Fire Weather Watch in effect from Saturday morning through
      Sunday morning for zones 288-354-355-358-362-369>380. (See LAXRFWLOX).
     Fire Weather Watch in effect from Friday afternoon through
      late Friday night for zones 350-352-353. (See LAXRFWLOX).
PZ...Small Craft Advisory in effect until 3 AM PST Friday for
      zones 645-655. (See LAXMWWLOX).
     Small Craft Advisory in effect until 10 AM PST Friday for
      zone 650. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PST Saturday for
      zone 670. (See LAXMWWLOX).
     Gale Warning in effect until 9 PM PST Friday for zones
      673-676. (See LAXMWWLOX).

&&

PUBLIC...MW
AVIATION...Smith
MARINE...Smith
BEACHES...Sweet/Schoenfeld
SYNOPSIS...MW/Smith

weather.gov/losangeles

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