Frost Advisory 21, NWS Los Angeles, CA

150 
WWUS76 KLOX 201140
NPWLOX

URGENT - WEATHER MESSAGE
National Weather Service Los Angeles/Oxnard CA
340 AM PST Tue Dec 20 2022

CAZ088-357>359-363-547-201600-
/O.CON.KLOX.FR.Y.0021.000000T0000Z-221220T1600Z/
Santa Clarita Valley-Ojai Valley-Central Ventura County Valleys-
Southeastern Ventura County Valleys-Santa Monica Mountains-
Los Angeles County San Fernando Valley-
Including the cities of Castaic Lake, Newhall, Santa Clarita, 
Valencia, Oak View, Ojai, Fillmore, Piru, Santa Paula, Moorpark, 
Newbury Park, Simi Valley, Thousand Oaks, Burbank, Northridge, 
Universal City, and Woodland Hills
340 AM PST Tue Dec 20 2022

...FROST ADVISORY REMAINS IN EFFECT UNTIL 8 AM PST THIS MORNING...

* WHAT...Temperatures as low as 32 will result in frost 
  formation. Isolated temperatures in the mid to upper 20s are 
  possible through the canyons of the Santa Monica Range.

* WHERE...Santa Clarita Valley, Ojai Valley, Central Ventura 
  County Valleys, Southeastern Ventura County Valleys, Santa 
  Monica Mountains and Los Angeles County San Fernando Valley.

* WHEN...Until 8 AM PST this morning.

* 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.

&&

$$

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
216 PM PST Mon Dec 19 2022

.SYNOPSIS...19/216 PM.

Slightly below normal temperatures with bouts of high clouds are
expected through the middle of this week. An amplifying trough
over the Central U.S. will support breezy northerly winds to many
interior areas mid to late week. A significant warming trend is
expected later in the week and the weekend.

&&

.SHORT TERM (TDY-THU)...19/213 PM.

A ridge of high pressure will continue to dominate the west coast
of North America for the next several days, though small impulses
will move through the ridge at times. One of those impulses will
be tonight and will be accompanied by increasing high clouds but
no rain. The added clouds should help provide some additional
insulation that will make temps not quite as cold tonight in most
areas. Still, another frost advisory will be in effect for parts
of LA/Ventura Counties with the coldest areas (Santa Monica
Mountains) again dropping into the 20s.

Otherwise, not too much impactful weather through the short term.
Following this first impulse will be increasing north to northeast
flow that will create some gusty winds Wednesday into Thursday in
the Santa Ynez Range and the LA/Ventura Mountains. These winds may
reach advisory levels at times. The offshore flow and warming air
mass will lead to warmer temps overall with highs getting back
into the lower 70s across the valleys and even some coastal areas
inland from the beaches.

.LONG TERM (FRI-MON)...19/213 PM.

After the last impulse comes through late Thursday the west coast
ridge is expected to amplify into a monster 588-591dam bubble that
will boost temps well into the 70s and likely a sprinkling of
lower 80s in parts of LA/Ventura Counties over the holiday
weekend. Gradients will be lightly offshore and likely not enough
to generate any significant winds, but enough to hold back the
cool sea breeze long enough for temps to warm up to levels we
haven't seen since Thanksgiving. Warm weather expected to linger
into early next week before the ridge is pushed east and cooler
onshore flow returns along with a weak trough.

&&

.AVIATION...19/1736Z.

At 1723Z, there was no marine layer or inversion at KLAX.

High confidence in VFR TAFs for KBUR, KVNY, KPMD, and KWJF.

There is a 20-30 percent chance of IFR cigs/vsbys after 06Z for
coastal TAFs KSBA and south including KLAX.

Low confidence in KSMX, KSBP, and KPRB with a 20-40 percent
chance of IFR or lower cigs/vsbys after 06Z.

KLAX...There is a 30 percent chance of IFR cigs/vsbys after 06Z.
Any east wind component should remain safely below 8 kts.

KBUR...VFR conds are expected thru the period with light wind.

&&

.MARINE...19/110 PM.

No change to the marine forecast in the afternoon issuance.

There is a 30 percent chance of Small Craft Advisory conditions
by late Tuesday focused across the Outer Waters south of Point
Sal, increasing to 50-70 percent Wednesday and Thursday.
Patchy low clouds and dense fog will return to some waters
this morning and may continue at times, especially late night to
early morning hours through Wednesday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Frost Advisory in effect from midnight tonight to 8 AM PST
      Tuesday for zones 88-357>359-363-547. (See LAXNPWLOX).
PZ...NONE.

&&

PUBLIC...MW
AVIATION...Sweet/Munroe
MARINE...Sweet/Munroe
SYNOPSIS...MW

weather.gov/losangeles

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