High Wind in California, January 26, 2023

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
939 PM PST Wed Jan 25 2023

.SYNOPSIS...25/706 PM.

Strong Santa Ana winds are expected to develop tonight through
Thursday, while warmer than normal temperatures will last through
Friday. Much cooler temperatures are expected over the weekend,
with a chance of light rain Sunday and Monday. Dry but cool
weather is expected Tuesday and Wednesday of next week.

&&

.SHORT TERM (WED-SAT)...25/752 PM.

***UPDATE***

Santa Ana winds are affecting portions of the area this evening,
and they will continue to ramp up over the next few hours. So far,
gusts of 40 to 45 mph have been observed over the LA interior
mountains, and in the Malibu Hills, with gusts up to 35 mph in
some of the Ventura and LA valleys and foothills. The NAM12 and
WRF models indicate that the most widespread strong winds may
be delayed until the early morning hours (3-5 AM), persisting
through around noon Thursday. At 12Z (4M) the NAM shows the peak
in offshore gradients between LAX to Daggett, with -6.3 mb. A
strong warning event is expected for the LA mountains, including
the Santa Monicas, with gusts 60-75. Isolated stronger gusts are
not out of the question, especially in offshore wind hot spots
like the Magic Mtn Truck Trail. The Ventura Mountains and Santa
Clarita Valley will see a somewhat weaker warning, with peak gusts
up to 60 mph. The valleys and coast will see strong Advisory
level gusts to 45 to 50 mph. Thanks to a slightly more easterly
component to these Santa Anas, places like the western Santa
Monicas could see stronger winds than the eastern sections,
spreading down over the Oxnard Plain.

***From Previous Discussion***

Gusty offshore winds to continue through most of Thursday and
it's possible some of the warnings/advisories will need extending
beyond Thursday evening, especially the mountains. While there is
some cold air with this event, the downsloping winds will more
than compensate for that and keep temps across coast/valleys
warmer than normal through Thursday and likely into Friday as
well.

Still a little breezy into Friday but much less than Thursday.
Otherwise, little excitement in the weather.

Big changes in the weather starting Saturday with much cooler
temperatures and possibly even some marine layer clouds or
afternoon stratocu. A weak trough will be dropping south through
California causing temperatures to drop several degrees. No
precip expected yet but definitely cooler with higher humidities
as offshore flow turns onshore.

.LONG TERM (SUN-WED)...25/227 PM.

Confidence definitely growing with rain chances for Sunday/Monday
as a large majority of the ensemble solutions have at least some
precip. However, this is a north/south moving system with little
if any over-water trajectory so it's not surprising to see PW's
around .4" and forecast rain amounts mostly under a quarter inch.
Sunday will likely start of pretty cloudy as a second and much
colder trough drops through the state. Rapidly falling heights and
increasing onshore flow will likely spawn a deepening marine
inversion and increasing low clouds and fog across coast and
valleys and possibly even up the coastal mountain slopes. These
patterns often also cause drizzle or light rain well ahead of the
main front, especially south of Pt Conception where there is ample
upslope flow near the coastal mountains to create lifting in the
boundary layer. As a result, pops have been added to Sunday to
account for this possibility. At the very least it will be a
cool, cloudy day, but there's a good chance that there will be
some drizzle or light rain around with amounts under a tenth of an
inch.

Rain chances increase Sunday night into Monday as the upper low
gets closer and the main front moves through. Again, this has very
little moisture to work with but it's also very cold aloft so it
won't take much for light rain to reach the surface. This will
probably be more of a showery pattern than steady light precip,
and some areas may get very little measurable rain so pops are
going to be on the lower side for now. Snow levels will be
dropping rapidly Sunday night and any showers that form could drop
frozen precip down to as low as 2500 feet by Monday morning,
though likely very light and spotty accumulations. With the upper
low moving almost overhead Monday afternoon there is a non-zero
chance of convection, though given that the whole column is cold
chances for storms are less than would be expected with an upper
low so close.

Shower chances expected to taper off Monday night with dry but
chilly conditions expected Tuesday. Then warming up Wednesday as
a ridge of high pressure builds in from the west.

&&

.AVIATION...26/0538Z.

At 0512Z at KLAX, there was no marine layer. There was a surface-
based inversion with a top around 400 feet at a temperature of
17C.

High confidence in CAVU TAFs and moderate confidence in wind
speeds and timing of wind changes especially for KOXR, KCMA, KBUR,
and KVNY. Moderate UDDFS and LLWS are possible through Thursday
afternoon, especially near the higher terrain around Los Angeles
and Ventura Counties.

KLAX...High confidence in TAF. Any east wind component should
remain below 7 knots, but there is a 30 percent chance of east
winds of 10 knots Thursday morning.

KBUR...High confidence in TAF, except moderate confidence in wind
after 09Z where gusty NE winds may strengthen earlier than
forecast. A chance of LLWS and lgt ocnl mdt turbc will develop
after 09Z tonight.

&&

.MARINE...25/731 PM.

A moderate to locally strong Santa Ana wind event is expected
tonight through early Thursday afternoon. Gusty NE winds will
likely pick up across the waters from Point Mugu to Santa Monica
as well as through the San Pedro Channel after midnight. There is
a 60 percent chance of Gale force gusts across the most nearshore
waters from Point Mugu to Santa Monica and possibly out to Santa
Cruz Island (especially after dawn). The waters a bit farther out
past the Channel Islands and moving out to sea towards San Nicolas
Island will likely gust up to strong Small Craft Advisory level.
Through the San Pedro Channel out to Catalina Island models
indicate gusty winds, but likely not as strong as the main
corridor. Winds will likely be in the SCA level range with a 30
percent chance of Gales. Due to the gusty NE winds, east-facing
harbors such as Avalon Harbor, Two Harbors, and Smugglers Cove
should not be considered as safe harbor. For these areas there is
a 60-70 percent chance that easterly winds of 15 to 25 knots with
gusts to 30 knots and wind waves of 3 to 5 feet could enter the
harbors. There is a 20-30% chance that these winds continue into
the afternoon.

Winds will slowly diminish through the afternoon and into the
evening with a 20-30 percent chance of SCA level winds lingering
across the most nearshore waters Thursday night. By Friday winds
will calm down and a more normal NW flow pattern will re-establish
across the waters. SCA level NW winds may develop over the outer
waters by Friday or Saturday afternoons.

&&

.BEACHES...25/118 PM.

A long-period (15-18 seconds) W swell will continue to affect the
coastal waters into this evening. Thus, a High Surf Advisory
remains in effect for the Central Coast through 10pm this evening
for surf heights of 10 to 13 feet possible. High surf may continue
across the Ventura County coast. Therefore, a High Surf Advisory
is in effect through 6 pm for surf heights of 5 to 8 feet. Across
LA County, elevated surf will be likely but not quite to high
surf level. A Beach Hazards Statement for the LA County coast
(including the Malibu strip) is in effect through 6pm this
evening. The highest surf will be on west- facing beaches and
there will be an increased risk for strong, dangerous rip
currents.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Wind Warning in effect until 6 PM PST Thursday for zones
      53-88. (See LAXNPWLOX).
     High Wind Warning in effect until 10 PM PST Thursday for
      zones 54-363. (See LAXNPWLOX).
     Wind Advisory in effect until 6 PM PST Thursday for zones
      59-358-359-547. (See LAXNPWLOX).
     Wind Advisory in effect until 2 PM PST Thursday for zones
      87-354-355-362. (See LAXNPWLOX).
     High Surf Advisory in effect until 10 PM PST this evening for
      zones 340-346. (See LAXCFWLOX).
PZ...Small Craft Advisory in effect until noon PST Thursday for
      zones 650-676. (See LAXMWWLOX).
     Gale Warning in effect until noon PST Thursday for zone 655. (See LAXMWWLOX).

&&

PUBLIC...MW/Smith
AVIATION...Stewart
MARINE...Stewart
BEACHES...Sweet/Lund
SYNOPSIS...MW/Smith

weather.gov/losangeles

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