Wind Advisory 122, NWS Los Angeles, CA

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
958 PM PST Tue Nov 22 2022

.SYNOPSIS...22/119 PM.

Warm and dry conditions are expected across the area through
Friday with Thanksgiving Day likely the warmest day of the week.
Moderate to strong Santa Ana winds are expected Wednesday night
through Friday with critical fire weather conditions possible.
For the weekend, a cooling trend can be expected with a chance of
rain next week.

&&

.SHORT TERM (TUE-FRI)...22/921 PM.

***UPDATE***

Not too much to discuss in the way of weather for today with near
normal high temperatures and breezy offshore winds for the LA
County Mountains to the Sierra Madre Mountains. Skies remain
mostly clear, with around 5 degrees of warming Wednesday as
gradients remain offshore. The forecast for the upcoming wind
event Wednesday night into Thursday looks on track. With the NAM12
showing a peak LAX-DAG offshore gradient of -9 mb and decent cold
air advection, may see these strong winds mixing down into the LA
and Ventura County coasts. Wind advisories will likely be needed
for these locations, and also for the Ventura County mountains.
Will allow the next shift to assess the newest guidance before
issuing wind advisories.

***From Previous Discussion***

Overall, 12Z models in good synoptic agreement through the period.
At upper levels, ridge will build in from the west through Friday
as an inside slider drops across the Great Basin Thursday/Friday.
Near the surface, offshore flow will be on the increase through
Thanksgiving then will diminish on Friday.

Forecast-wise, main issue through the short term will be the
winds. 12Z deterministic and ensemble guidance still all points to
a moderate to strong Santa Ana wind event through the period.
North to northeast winds will increase Wednesday afternoon and
evening, peak in strength Thanksgiving morning then slowly
diminish Thursday night/Friday. Will anticipate widespread
northeasterly wind gusts 35-55 MPH on Thanksgiving across Ventura
and LA counties with a chance of 55-65 MPH gusts in the more
favored areas. So, will continue with a HIGH WIND WATCH for the LA
Mountains/Santa Clarita Valley/Ventura Valleys, but will add the
San Fernando Valley and Santa Monica Mountains to the watch for
late Wednesday through Thursday morning. For Thursday night and
Friday, the offshore winds will be weaker, but still likely be
widespread advisory-level winds across Ventura/LA counties. For
San Luis Obispo and Santa Barbara counties, the offshore winds
will be weaker (which is usual), but still will be some gusty
winds across the mountains and foothills (gusts 20-35 MPH
possible). For the latest details on the wind, check out
LAXNPWLOX.

Secondary issue will be temperatures across the area. With the
ridge building overhead and the offshore flow, a warming trend is
expected. By Thursday/Friday, high temperatures across the coasts
and coastal valleys will be in the mid 70s to lower 80s with
interior sections expected to have high temperatures in the mid
60s to mid 70s.

.LONG TERM (SAT-TUE)...22/120 PM.

Overall, 12Z models on the same broad synoptic page, but still
differ on the details. For Saturday/Sunday, cyclonic flow will
prevail aloft with a return of onshore flow near the surface. For
Monday and Tuesday, an upper low will move southeastward across
the state with models differing on the track of the system.

For Saturday/Sunday, no significant issues are anticipated. With
the cyclonic flow aloft, some high level clouds may drift across
the area. Additionally, the onshore flow near the surface will
allow for the marine layer stratus/fog to redevelop. With the
cloud cover and increasing onshore flow, temperatures will exhibit
a cooling trend through Sunday.

For Monday/Tuesday, unsettled weather can be expected for the area
as the upper low moves across the state. At this time, the GFS and
its ensembles are further west with the track of the low than the
ECMWF. So, the GFS would be a wetter solution through the period.
Still too much uncertainty to get specific with timing/amounts,
but there will be a decent chance of noticeable rainfall for all
areas.

&&

.AVIATION...23/0557Z.

At 0420Z at KLAX, there was no marine layer. There was a sfc based
inversion with a top of 1300 and a temperature of 19 C.

High confidence in CAVU TAFs.

KLAX...High confidence in CAVU TAF. Good confidence that any east
wind component will will be 6 kt or less.

KBUR...High confidence in TAF.

&&

.MARINE...22/729 PM.

Moderate confidence in winds at Small Craft Advisory (SCA) level
across the outer waters from the Central Coast to San Nicolas
Island through late tonight, with gusts to 25 knots. There is a
30-40% chance that SCA winds will continue through Wednesday, and
that they will reoccur again over the weekend.

A moderate to strong Santa Ana wind event is expected late
Wednesday night through Thursday which will likely bring SCA
level NE winds to the waters from Point Mugu to Santa Monica and
out to at least Santa Cruz Island. Higher end SCA level gusts to
30 kt are likely, especially closest to shore and out to Anacapa
Island. There is a 30% chance of Gale force gusts for the waters
closest to shore. Weaker NE winds are likely from the San Pedro
Channel out to Avalon Harbor with gusts of 15 to 20 kt possible.
With the SCA level winds, locally short-period, choppy seas can
be expected. Winds should diminish by Thursday evening, although
locally gusty conditions may linger through the night.

There will be an increasing long-period west swell Friday into
Saturday that may bring hazardous seas up to 10 feet across the
outer waters. In addition, there is the potential for elevated to
high surf conditions with high rip current risk.

&&

.FIRE WEATHER...22/1244 PM.

We have high confidence in a moderate to strong Santa Ana event ramping
up late Wednesday night, peaking Thursday, and tapering off into
Friday. This Santa Ana event will be a bit more out of the east than
recent events leading to more of a focus on the western San Fernando
Valley and western portions of the Santa Monica mountains. This
orientation typically provides more widespread gusty winds into coastal
areas of Ventura County as well. Winds gusts now expected to peak in
the 40 to 55 mph range except up to 65 mph within the HIGH WIND WATCH
for adjacent mountains and valleys of Los Angeles and Ventura Counties
(see NPWLOX for details). These winds combined with critically low
relative humidity values ranging between 5 and 15 percent provide about
a 70 percent chance of critical fire weather conditions starting early
Thursday morning, peaking in extent and intensity late morning into the
afternoon, and possibly continuing through Friday morning for wind
prone areas. A FIRE WEATHER WATCH has been posted for this time frame,
except a smaller window for coastal areas along and west of Malibu into
Coastal Ventura County centered on the daytime Thursday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Wind Watch in effect from Wednesday evening through
      Thursday afternoon for zones 54-88-358-359-363-547. (See LAXNPWLOX).
     Fire Weather Watch in effect from late Wednesday night
      through Friday morning for zones 254-288-358-359-363-547. (See LAXRFWLOX).
     Fire Weather Watch in effect from Thursday morning through
      Thursday evening for zones 354-355-362. (See LAXRFWLOX).
PZ...Small Craft Advisory in effect until 3 AM PST Wednesday for
      zones 670-673-676. (See LAXMWWLOX).

&&

PUBLIC...Phillips/Thompson
AVIATION...Rorke
MARINE...Stewart/Smith
FIRE...Munroe
SYNOPSIS...RAT

weather.gov/losangeles

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