Wind Advisory 10, NWS Los Angeles, CA

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
205 PM PST Tue Feb 1 2022

.SYNOPSIS...01/203 PM.

Gusty Santa Ana winds are expected late tonight through the
weekend, strongest on Wednesday. Temperatures will be cool through
Thursday then a warming trend is expected Friday into the middle
of next week.

&&

.SHORT TERM (TDY-FRI)...01/145 PM.

Low clouds have been stubborn to clear from much of the LA basin
and San Gabriel Valley as well as across the Santa Ynez range. As
northerly flow aloft strengthens through the afternoon and
evening, these clouds should start to dissipate. Low clouds banked
up against the north slopes are also starting to dissipate, but
there is a chance they may linger into the night. Otherwise mostly
clear skies should dominate.

Tonight marks the start of yet another extended period of gusty
offshore winds. A shortwave trough moves south through the main
flow into Southeast California tonight through Wednesday morning.
This will serve to strengthen the northerly flow aloft and bring
in colder air from the interior. Once the trough passes through
the synoptic pattern does not change much through Thursday, then a
weak upper-level low cuts off and traverses southward through the
coastal waters early Friday keeping offshore flow in place.

So let's break down the wind forecast. Starting late this
afternoon and this evening, north to northwest flow will increase
across southern Santa Barbara County. This will bring breezy
sundowners mainly to the western half from Gaviota to Refugio,
likely remaining below advisory level. Of course some localized
gusts to 45 mph are possible below the favored passes and canyons.
Breezy winds are also likely to extend to the eastern side around
the Montecito hills as well. Later on in the evening and into the
overnight hours the winds will shift to a more northeasterly
direction as the LAX-DAG gradient strengthens to near -5 mb by
early Wednesday. This will shift the focus to the Santa Ana wind
corridors across LA and Ventura Counties which will continue
through the period. Winds should pick up across the higher
elevations late evening, then filter down to the wind-prone
valleys and coastal areas by Wednesday morning. With lots of
upper-level support and cold air advection to work with, winds
across the mountains will likely gust at least 60 mph. Localized
gusts even higher are possible across the wind "magnets" such as
Magic Mountain Truck Trail. The High Wind Watch over the LA County
mountains has been upgraded to a High Wind Warning in effect from
10pm tonight through noon on Thursday. Wind Advisories have been
issued for the other Santa Ana wind-prone areas for the same time
period, including the coastal areas from Ventura to the Hollywood
Hills. A question on many people's minds will be whether the San
Gabriel Valley will be impacted by this event. Let's take a brief
technical look. Winds aloft at the 850 mb level are classically
from the northeast, but at the 700 mb level and above is more
northerly. In addition, there will be good subsidence with a
stable layer at the ridgetops combined with lots of cold air. So
it is possible gusty winds may filter down into the foothills of
the valley. High resolution models indicate gusty winds filtering
down north of the 210 corridor mainly over the western valley
around Altadena and Pasadena. As a result, a Wind Advisory will be
in effect but only for these localized portions of the valley with
gusts up to 40 mph. It's also worth noting the eastern San
Fernando Valley will also likely see some gusty winds, including
the Burbank area. The timing of the strongest winds is a little
complicated and dependent on location, but in general the
strongest winds will continue through Wednesday night. Winds will
taper off gradually through Thursday as support aloft weakens then
pick back up Thursday night. There will be another peak in winds
on Friday, and the EPS meteograms are honing in on the peak Friday
afternoon. This peak will likely not be as strong as Wednesday
with gusts peaking between 25 and 45 mph.

As for weather items other than wind, we'll just see continued
cool temperatures Wednesday and Thursday, although with weaker
winds there should be a few degrees of warming on Thursday. Even
more warming is expected Friday where we could see a couple areas
hitting 70 again.

.LONG TERM (SAT-TUE)...01/157 PM.

For the weekend into early next week, you guessed it, offshore
flow is expected to continue. Both the GFS and ECMWF and their
ensembles are forecasting a return to ridging over the West Coast
but differ in how they exactly handle the pattern. There is still
a lot of spread in the ensemble solutions, but they are hinting in
a couple peaks in offshore flow on Sunday and another mid to late
next week. At this point, winds look like they will remain below
advisory level with peak gusts in the 25 to 45 mph range.

Unfortunately the forecast looks dry through at least the middle
of February, but even then only a few ensemble solutions indicate
very light rain. Offshore flow will also keep skies mostly clear
through the period with no stratus expected for the time being.
Temperatures will be the talk of the town for next week. A warming
trend is expected each day with high temperatures as high as the
mid to upper 70s across the coastal valleys.

&&

.AVIATION...01/1916Z.

At 1739Z at KLAX, the marine layer was 2500 ft deep. The top of
the inversion was at 4700 ft with a temp of 9 C.

Low confidence in coastal/valley TAFs, and higher confidence in
the desert TAFs.

North of Point Conception...The TAF sites are expected to be
clear for the entire period.

South of Point Conception...The weather pattern on the south
coast will undergo a stark transition from a fairly deep marine
layer and catalina eddy to a moderate to strong Santa Ana wind
event. One of the critical questions will be the timing for the
arrival of the winds. We may have the marine clouds reform this
evening with MVFR conditions only to suddenly clear out around 06z
with the arrival of the offshore push. There is a 30 percent
chance that all coastal and valley TAF sites may see a brief
return of the marine layer this evening. For now, have left the
TAF sites clear for tonight, but this may change.

KLAX...Low confidence in the 18z TAF. Cigs may dissipate and
reform randomly for a time this afternoon. There is a 30 percent
chance of a brief period of MVFR ceilings this evening until the
offshore push around 06z. There is a 20-30% chance of a 7 kt east
wind component between 09-18Z Wed.

KBUR...Low confidence in the 18z TAF. There is a 30 percent
chance of a brief period of MVFR ceilings this evening until the
offshore push around 06z.

&&

.MARINE...01/106 PM.

Small Craft Advisory (SCA) level NW winds will affect areas
offshore of the Central Coast to San Nicolas Island through the
morning and into the afternoon. The winds over the outer waters
will strengthen to Gale Force in the afternoon and continue into
late tonight, thus, a Gale Warning has been issued. There is a
moderate chance of SCA level winds over the western portion of the
Santa Barbara Channel this afternoon and evening.

Significantly large short-period seas will result everywhere from
these winds, peaking somewhere between 10 and 14 feet off the
Central Coast, and 6 to 8 feet nearshore from Santa Barbara to
Orange County.

Issued a SCA for NE winds from Ventura to Santa Monica nearshore
starting late tonight through Thursday morning. Gusty winds may
even linger into early Friday. There is a 40 percent chance that
NE winds of 15 to 25 kt will reach Avalon Harbor, creating
breaking waves in the harbor. See the product LAXMWSLOX for more
infomation.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect from 10 PM this evening to noon PST
      Thursday for zones 40-41-44>46-53-88-547. (See LAXNPWLOX).
     High Wind Warning in effect from 10 PM this evening to noon
      PST Thursday for zone 54. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect from 3 AM Wednesday to 8 AM
      PST Thursday for zones 650-655. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 PM PST this afternoon
      for zones 670-673-676. (See LAXMWWLOX).
     Gale Warning in effect until 3 AM PST Wednesday for zones
      670-673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK (FRI-TUE).

Gusty north to northeast winds are expected Friday through the
weekend.

&&

PUBLIC...Stewart
AVIATION...Sweet/Lund/Rorke
MARINE...Sweet/Lund
SYNOPSIS...Stewart

weather.gov/losangeles

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