Winter Storm and High Wind in California, November 8, 2022

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
337 AM PST Tue Nov 8 2022

.SYNOPSIS...08/334 AM.

An early season significant winter storm will bring widespread
moderate to heavy rain and mountain snow to the region through
tonight. A weak to moderate Santa Ana late in the week may bring
gusty winds and warm temperatures closer to normal.

&&

.SHORT TERM (TDY-THU)...08/335 AM.

The latest satellite continued to show cooling cloud tops across
the coastal waters associated with a weak and diffuse warm front
that has formed in advance for the next cold front. Falling 500 mb
heights to our west through this morning will help to sharpen
southerly flow enhancing the warm advecting pattern while it
slowly sliding to the east. HREF ensemble guidance continued to
show increasing rainfall rates through this morning associated
with the warm front axis of moisture and the along and just ahead
of the cold front, which is poised to slide southeast through the
region from roughly mid morning to mid or late afternoon.
Widespread moderate to locally heavy rainfall with rates exceeding
a half of an inch per hour at times focused across southwest
facing slopes and adjacent foothills. Deep moisture extending up
to above -10 C at times thanks to a combination of weak
instability, isentropic lift, and orographics supports the threat
of isolated thunderstorms, along and behind the cold front. In
fact, there was a cluster of frequent lightning already of display
just west of Monterey Bay early this morning. Peak rainfall rates
may exceed one inch and even locally one and a half inches in
thunderstorms and areas of stronger upslope flow (most notably San
Lucia (northwest SLO county) and San Gabriel (eastern LA county
mountain ranges. These peak rates which are unchanged from
previous forecasts support the current Flood Watch for first and
second year burn scars of LA county, although significant flash
flooding or a stronger debris flow can't be completely ruled out
elsewhere where thunderstorms develop. Overall no significant
change in the rainfall forecast, although some coastal areas may
end up closer to the forecasted one inch as opposed to three
inches. Coastal mountain slopes and foothills are still on track
for 2-5 inches with local 6 inches possible.

Snow levels continue to be on the high side, around 7000 feet and
may increase to closer to 8000 feet across LA county in
particular under the warm advective pattern through early
afternoon. As snow levels fall tonight, at least light
accumulations are possible down to 5000 feet, locally down to
around 4000 feet. In fact, HREF guidance shows about a 20 percent
chance of a dusting on the I-5 corridor at the Tejon pass with
temperatures dipping to near freezing Wednesday morning, possibly
creating hazardous driving conditions there. All told we are
advertising 6-12 inches with local 20+ inches above 7000 feet,
with 3-6 inches between 5500-7000 feet. With snow already observed
on area ski resort webcams, we have opted to start the Winter
Storm Warning a bit early for the Los Angeles and Ventura county
mountains.

Guidance continued to indicate a 45-55 kt low level jet with
mountain wave activity likely intensifying downstream of the
mountains across interior areas such as the the interior mountains
and adjacent valleys including the Cuyama and Antelope Valleys,
likely supporting peak gusts in the 60-70 mph range (strongest
Antelope Valley). A High Wind Warning remains in effect for today
for these areas. Increase warm air advection and tightening
pressure gradients will support advisory level winds just about
everywhere else. For the few areas that may stay just below
advisory levels ahead of the front, will most certainly at least
briefly hit advisory levels along and just behind the front from
mid morning through mid afternoon.

Rain and mountain snow showers will dwindle in coverage tonight
into Wednesday with little to no additional accumulations
expected from Wednesday afternoon onward. Breezy, but likely
sub-advisory northerly winds are expected in the wake of this
system Wednesday, which will largely ward off frost/freeze
concerns Wednesday morning. Good radiational cooling conditions
with light winds and clear skies may set the stage for widespread
frost/freeze conditions focused across interior valleys, but may
creep into normally colder coastal valleys as well.

.LONG TERM (FRI-MON)...08/335 AM.

Ensemble guidance (GEFS ECS GEPS) indicates below normal
confidence in the extended period, although as a whole it appears
to be a relatively quiet stretch.

Guidance is trending towards a moderate Santa Ana event Friday
with advisory level winds in play for the typical areas with
temperatures rebounding closer to seasonal levels to the west of
the mountains, but remaining on the cool side to the east.

A weak disturbance could push into the area as early as this
weekend, but it may be battling against dry low levels left over
from the Santa Ana, so there is a slight (10-20 percent) chance
of showers with this system mainly north of Point Conception. A
more organized system may push into the region early next week,
but still shouldn't be a big deal.

&&

.AVIATION...08/0626Z.

At 06Z at KLAX, there was no marine layer.

Low confidence in TAFs. There is a 10-20% chance of isolated Tstorms
north of Point Conception (12Z Tue-12Z Wed) and south (18Z
Tue-00Z Wed). Brief 1sm +RA ovc003-006 is possible along and just
ahead of the cold front as well as in any TSRA, with a wind shift
of at least 30 degrees probable. Cold front is expected to pass
KSMX and north by 12-18Z, 18-00Z KSBA/KOXR/KCMA, and 21-03Z
elsewhere. Mostly MVFR-IFR cigs expected with rain showers.

Weak to brief moderate LLWS is probably near the cold front, with
periods of moderate LLWS possible for KPMD and KWJF after 12Z.

KLAX...Low confidence in TAF. Timing of rain and flight cat
changes may be off by three hours and more than one flight cat.
Brief 1sm +RA ovc003-006 is possible along and just ahead of cold
front (likely after 18Z) and in isolated TSRA (10-20% chance
18Z-00Z), with a wind shift of at least 30 degrees probable.
There is a 70 percent chance that the east wind component reaches
or exceeds 8 knots at times 12-18Z.

KBUR...Low confidence in TAF due to approaching cold front.
Timing of rain and associated flight cat changes may be off by
three hours and one flight cat. Brief 1sm +RA ovc003-006 is
possible along and in isolated TSRA (10-20% chance
18Z-00Z), and just ahead of a cold front (likely after 21Z).

&&

.MARINE...07/933 PM.

An early season strong winter storm will bring strong winds,
large, choppy seas and rain tonight through Tuesday. Seas may
trend a few feet higher than forecast, as Buoy 46028 peaked at 14
feet and Buoy 46011 reached 11 feet this evening. Will keep a
close eye on things to see if the swell should be increased
slightly.

First, strong south to southeast Small Craft Advisory (SCA) level
winds will develop tonight just ahead of the approaching system,
beginning in the northern waters. Winds will build further as the
front nears, likely reaching near Gale Force. Therefore, the Gale
Watch has been converted to a Gale Warning for the northern waters
off the Central Coast in effect from 4AM to Noon Tuesday. Over
the southern waters south of the Channel Islands, south to
southwest winds should reach SCA levels by 1 AM Tuesday. These
winds will become more widespread, and are expected to reach Gale
Force as well. Following the front, winds shift to the west and
are more likely to be just SCA levels. Minor timing adjustments
were made to the southern waters SCAs to account for earlier
arrival of strong winds. Gale Warnings look on track, but did
start the Gale Warning for the southern most waters earlier (7AM)
to be consistent with guidance. This will be a relatively faster
moving system where the strongest winds may be shorter-lived, but
could affect a large area over time.

These strong southerly winds expected overnight into Tuesday will
be disruptive and hazardous. Furthermore, there is also the
chance of isolated thunderstorms that can create gusty and
erratic winds, steep seas, and dangerous lightning.

SCA seas should linger into early Wednesday if not Wednesday
night, most likely across the outer waters. There is a 40% chance
for SCA level areas near the Bight Wednesday afternoon/evening.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Winter Storm Warning in effect until 10 AM PST Wednesday for
      zones 53-54. (See LAXWSWLOX).
     Flood Watch in effect through this evening for zones
      54-59-88-548. (See LAXFFALOX).
     High Wind Warning in effect from 8 AM this morning to 10 PM
      PST this evening for zone 59. (See LAXNPWLOX).
     Wind Advisory in effect until 9 PM PST this evening for zone
      87. (See LAXNPWLOX).
     Wind Advisory in effect until 6 PM PST this evening for zones
      88-349>352-354>359-362>365-547-548. (See LAXNPWLOX).
     High Surf Advisory in effect until 9 AM PST Wednesday for
      zones 340-346. (See LAXCFWLOX).
     Wind Advisory in effect until 1 PM PST this afternoon for
      zones 340>344-346>348. (See LAXNPWLOX).
     High Wind Warning in effect from 7 AM this morning to 4 PM
      PST this afternoon for zones 345-353. (See LAXNPWLOX).
PZ...Gale Warning in effect until 1 PM PST this afternoon for
      zones 645-670-673. (See LAXMWWLOX).
     Small Craft Advisory in effect until 7 AM PST this morning
      for zones 650-655-676. (See LAXMWWLOX).
     Gale Warning in effect from 7 AM this morning to 8 PM PST
      this evening for zones 650-655-676. (See LAXMWWLOX).

&&

PUBLIC...Munroe
AVIATION...Munroe/Lund
MARINE...Phillips/Sweet
SYNOPSIS...Munroe

weather.gov/losangeles

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

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
1140 PM PST MON NOV 7 2022

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0140 AM     NON-TSTM WND GST 7 ESE ACTON             34.42N 118.09W
11/07/2022  M56 MPH          LOS ANGELES        CA   MESONET

            MESONET STATION 555SE N3 HIGHWAY (SCE).

0930 AM     NON-TSTM WND GST 8 S AGUA DULCE          34.39N 118.34W
11/07/2022  M61 MPH          LOS ANGELES        CA   MESONET

            MESONET STATION SE678 MAGIC MTN TRUCK TRL
            (SCE).

0730 PM     NON-TSTM WND GST 6 NE AGUA DULCE         34.57N 118.27W
11/07/2022  M68 MPH          LOS ANGELES        CA   MESONET

            MESONET STATION SE444 SIERRA PELONA WEST
            (SCE).

&&

HALL