Frost Advisory 11, NWS Los Angeles, CA

233 
WWUS76 KLOX 280158
NPWLOX

URGENT - WEATHER MESSAGE
National Weather Service Los Angeles/Oxnard CA
558 PM PST Mon Dec 27 2021

CAZ059-280300-
/O.CAN.KLOX.WI.Y.0127.000000T0000Z-211228T0600Z/
Antelope Valley-
Including the cities of Lancaster and Palmdale
558 PM PST Mon Dec 27 2021

...WIND ADVISORY IS CANCELLED...

Although gusty winds remain near the foothills, wind speeds have 
decreased across the advisory area.

$$

CAZ037-038-051-280300-
/O.EXP.KLOX.WI.Y.0127.000000T0000Z-211228T0200Z/
San Luis Obispo County Interior Valleys-Cuyama Valley-
San Luis Obispo County Mountains-
Including the cities of Paso Robles, Atascadero, Cuyama, 
and Black Mountain
558 PM PST Mon Dec 27 2021

...WIND ADVISORY WILL EXPIRE AT 6 PM PST THIS EVENING...

Wind speeds have decreased across the advisory area.

$$

CAZ044>046-088-547-280800-
/O.CON.KLOX.FR.Y.0011.211228T0800Z-211228T1600Z/
Ventura County Interior Valleys-Ventura County Coastal Valleys-
Santa Monica Mountains Recreational Area-Santa Clarita Valley-
Los Angeles County San Fernando Valley-
Including the cities of Santa Paula, Fillmore, Ojai, Piru, 
Thousand Oaks, Simi Valley, Moorpark, Newbury Park, 
Santa Clarita, Newhall, Valencia, Woodland Hills, Northridge, 
Burbank, and Universal City
558 PM PST Mon Dec 27 2021

...FROST ADVISORY REMAINS IN EFFECT FROM MIDNIGHT TONIGHT TO 8 AM
PST TUESDAY...

* WHAT...Temperatures as low as 32 will result in frost 
  formation. Isolated pockets of temperatures near 30 are 
  possible in the Ojai Valley and near Malibu Canyon and Agoura. 

* WHERE...Ventura County Interior Valleys, Ventura County 
  Coastal Valleys and Santa Clarita Valley. 

* WHEN...From midnight tonight to 8 AM PST Tuesday.

* IMPACTS...Frost can damage sensitive plants and harm pets if 
  left unprotected. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$

Jackson

335 
WWUS76 KLOX 280755
NPWLOX

URGENT - WEATHER MESSAGE
National Weather Service Los Angeles/Oxnard CA
1155 PM PST Mon Dec 27 2021

CAZ044>046-088-547-281600-
/O.CON.KLOX.FR.Y.0011.211228T0800Z-211228T1600Z/
Ventura County Interior Valleys-Ventura County Coastal Valleys-
Santa Monica Mountains Recreational Area-Santa Clarita Valley-
Los Angeles County San Fernando Valley-
Including the cities of Santa Paula, Fillmore, Ojai, Piru, 
Thousand Oaks, Simi Valley, Moorpark, Newbury Park, 
Santa Clarita, Newhall, Valencia, Woodland Hills, Northridge, 
Burbank, and Universal City
1155 PM PST Mon Dec 27 2021

...FROST ADVISORY REMAINS IN EFFECT UNTIL 8 AM PST TUESDAY...

* WHAT...Temperatures as low as 32 will result in frost 
  formation. Isolated pockets of temperatures near 30 are 
  possible in the Ojai Valley and near Malibu Canyon and Agoura.

* WHERE...Ventura County Interior Valleys, Ventura County 
  Coastal Valleys and Santa Clarita Valley.

* WHEN...Until 8 AM PST Tuesday.

* IMPACTS...Frost can damage sensitive plants and harm pets if
  left unprotected.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$

Hall

153 
WWUS76 KLOX 281544
NPWLOX

URGENT - WEATHER MESSAGE
National Weather Service Los Angeles/Oxnard CA
744 AM PST Tue Dec 28 2021

CAZ044>046-088-547-281645-
/O.EXP.KLOX.FR.Y.0011.000000T0000Z-211228T1600Z/
Ventura County Interior Valleys-Ventura County Coastal Valleys-
Santa Monica Mountains Recreational Area-Santa Clarita Valley-
Los Angeles County San Fernando Valley-
Including the cities of Santa Paula, Fillmore, Ojai, Piru, 
Thousand Oaks, Simi Valley, Moorpark, Newbury Park, 
Santa Clarita, Newhall, Valencia, Woodland Hills, Northridge, 
Burbank, and Universal City
744 AM PST Tue Dec 28 2021

...FROST ADVISORY WILL EXPIRE AT 8 AM PST THIS MORNING...

Temperatures in the advisory area have risen into the mid-30s or
higher so the frost advisory will expire at 8am.

$$

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
208 PM PST Mon Dec 27 2021

.SYNOPSIS...27/204 PM.

A wet and unsettled weather pattern will continue through
Thursday. Rain and mountain snow will taper off this evening but
return again Wednesday and Thursday. Temperatures will remain
significantly below average for this time of year with cold
overnight temperatures expected away from the coast. Dry weather
is expected Friday through the upcoming holiday weekend.

&&

.SHORT TERM (TDY-THU)...27/158 PM.

Quick moving system dropping some light to locally moderate
precip across the area today. This one is tracking from the north
with very little southerly flow so highest totals and rates are
across western SLO/Santa Barbara Counties and possibly eastern LA
County. However, even the higher end rates are not expected to
pose any debris flow issues so overall mostly a beneficial rain
event for lower elevations. Mountains above 5000' will get snow
through this evening but it will be tapering off quickly in most
areas except possibly lingering near the Kern County line with
possibly some light accumulations down to around 4000-4500'.

A chilly night tonight, especially in areas where the clouds clear
which looks to be across LA/Ventura Counties. While there will be
small pockets of freezing temperatures it looks like most areas
will stay at least slightly above freezing and will go with frost
advisories there.

Tuesday should be dry for the most part but cool with highs only
in the 50s which is a good 10 or more degrees below normal for
most coast/valley areas. A frost advisory will be in effect for
some LA/Ventura valley areas tonight with isolated pockets of near
to slightly below freezing temps in places like Ojai and the
Malibu Canyon area near the LA/Ventura County line.

The next system for Wed/Thu continues to provide some challenges
in terms of timing and amounts. Latest ensemble guidance suggests
the heavier precip amounts will favor LA County which is similar
to the deterministic runs, though the GFS is certainly an outlier
as it shows the system stalling there for several hours Thursday.
Most of the ensemble members fall in the 1.5-2" range for lower
elevations of LA County Wednesday into Thursday and with upslope
enhancement those numbers could easily reach 3" or even more.

Rain amounts drop off west and north as models favor a faster
track through those areas, but earlier model solutions had shown
higher numbers there and less over LA so confidence still on the
low side where the heaviest rain will fall. However, at this time
it certainly favors LA County.

Snow levels will be on the low side with this event with several
inches of snow expected above 5000'. If the front slows down over
LA County accumulations there could easily exceed a foot. At this
time not expecting significant accumulations over the Grapevine
but there is a chance of some light snow there at the beginning
and end of the event early Wednesday and late Thursday when snow
levels are lowest.

.LONG TERM (FRI-MON)...27/203 PM.

Friday through the New Year's weekend expected to be dry and cool
with highs mostly in the 50s which is a good 10 or more degrees
below normal for many lower elevation locations. Models show a
weak upper level ridge coming in that will give southern
California a little break in the wet weather but temps will remain
below normal.

&&

.AVIATION...27/1758Z.

At 17Z at KLAX, there was no marine inversion.

Fast moving frontal system will push across the region today and
early tonight. Showers with the front will push into SLO and SBA
Counties thru late this morning, and into VTU and L.A. Counties
during the afternoon. Showers will end in northern areas by
evening, and across eastern L.A. County during this evening, with
VFR cigs overnight into Tue morning.

Conditions will be generally MVFR much of the time through this
evening, except possibly IFR in heavier showers. Strong and gusty
SW-W winds will affect coastal airfields, around KPRB and in the
Antelope Valley through this evening.

KLAX...Moderate confidence in the 18Z TAF. There is a 20-30%
chance that MVFR cigs could arrive before 21Z. There is a 20-30%
chance that showers will develop as early as 19Z. There is a 20%
chance that MVFR conds will persist thru the night and not improve
to VFR until Tue morning.

KBUR...Moderate confidence in the 18Z TAF. There is a 20-30%
chance that showers will develop as early as 19Z. There is a 20%
chance that MVFR conds will persist thru the night and not improve
to VFR until Tue morning.

&&

.MARINE...27/133 PM.

In the outer waters, Gale force winds are expected for the central
and southern zones (PZZ673-676) through late tonight, while Small
Craft Advisory (SCA) winds and seas will prevail for the northern
zone (PZZ670). After that, SCA conditions will likely continue
Tue morning either due to winds and/or seas, then conds will drop
below SCA levels Tue afternoon and remain below SCA levels thru
Thu night. There is a 40% chance of SCA level N winds late Thu
night, then SCA level NW to N winds are likely Fri and Sat.

In the inner waters north of Pt Sal, winds and seas will increase
to SCA levels by late today. SCA conditions are expected thru
late tonight due at least to wind and seas. SCA conds are not
expected Tue thru Sat except for a 30% chance of SCA level NW
wind gusts on Fri.

In the SBA Channel and the inner waters S of Pt. Mugu, SCA level
winds and seas are expected from late today through late tonight,
then SCA conditions may continue for the southern areas Tue
morning. SCA conds are not expected Tue afternoon thru Sat, except
for a 40% chance of SCA level NW winds Fri.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect until 6 PM PST this evening for zones
      37-38-51. (See LAXNPWLOX).
     Frost Advisory in effect from midnight tonight to 8 AM PST
      Tuesday for zones 44>46-88-547. (See LAXNPWLOX).
     Winter Storm Warning in effect until 10 PM PST this evening
      for zones 52>54. (See LAXWSWLOX).
     Wind Advisory in effect until 10 PM PST this evening for zone
      59. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 AM PST Tuesday for
      zones 645-650. (See LAXMWWLOX).
     Small Craft Advisory in effect until 9 AM PST Tuesday for
      zones 655-670. (See LAXMWWLOX).
     Gale Warning in effect until 3 AM PST Tuesday for zones
      673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK (THU-MON).

Heavy rain and mountain snow will create hazardous driving
conditions Thursday. Overnight temperatures will drop below
freezing across some valley areas through the weekend.

&&

PUBLIC...MW
AVIATION...DB/Sirard
MARINE...Sirard
SYNOPSIS...MW

weather.gov/losangeles