Alert archive / California / Frost Advisories in 2021

Frost Advisory 4, NWS San Diego, CA

October 12, 2021San Bernardino County, California

NWS San Diego, CA issued this frost advisory at Oct 12, 2021, 12:57 PM PDT for San Bernardino County, California. It took effect at Oct 13, 2021, 12:00 AM PDT. It was in force for 9 hr.

The area

The counties it named.

The facts

Issued
Oct 12, 2021, 12:57 PM PDT (19:57 UTC)
In effect from
Oct 13, 2021, 12:00 AM PDT
Expired
Oct 13, 2021, 9:00 AM PDT
In force
9 hr
Issued by
NWS San Diego, CA

County San Bernardino County, CA

The radar

The Edwards AFB radar (KEYX), 129 km from the middle of the area, began a volume at 19:57 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Las Vegas, NV (KVEF), launched 12:00Z, 8.0 hours before the alert went out and 180 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Las Vegas, NV at 12:00Z on 2021-10-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Las Vegas, NV at 12:00Z on 2021-10-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -80 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1720 m above ground
0-6 km bulk shear
2 kt
0-1 km storm-relative helicity
-80 m²/s²
0-3 km storm-relative helicity
-49 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

879 
WWUS76 KSGX 121957
NPWSGX

URGENT - WEATHER MESSAGE
National Weather Service SAN DIEGO CA
1257 PM PDT Tue Oct 12 2021

CAZ060-130500-
/O.NEW.KSGX.FR.Y.0004.211013T0700Z-211013T1600Z/
Apple and Lucerne Valleys-
Including the cities of Hesperia and Apple Valley
1257 PM PDT Tue Oct 12 2021

...FROST ADVISORY IN EFFECT FROM MIDNIGHT TONIGHT TO 9 AM PDT
WEDNESDAY...

* WHAT...Temperatures between 28 and 33 degrees will result in 
  frost formation.

* WHERE...Apple and Lucerne Valleys.

* WHEN...From midnight tonight to 9 AM PDT Wednesday.

* IMPACTS...Frost could kill sensitive outdoor vegetation if 
  left uncovered.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$

For more information from the National Weather Service visit
http://weather.gov/sandiego
2 follow-up statements
189 
WWUS76 KSGX 130446
NPWSGX

URGENT - WEATHER MESSAGE
National Weather Service SAN DIEGO CA
946 PM PDT Tue Oct 12 2021

CAZ060-131300-
/O.CON.KSGX.FR.Y.0004.211013T0700Z-211013T1600Z/
Apple and Lucerne Valleys-
Including the cities of Hesperia and Apple Valley
946 PM PDT Tue Oct 12 2021

...FROST ADVISORY REMAINS IN EFFECT UNTIL 9 AM PDT WEDNESDAY...

* WHAT...Temperatures between 29 and 34 degrees will result in 
  frost formation.

* WHERE...Apple and Lucerne Valleys.

* WHEN...From midnight tonight to 9 AM PDT Wednesday.

* IMPACTS...Frost could kill sensitive outdoor vegetation if 
  left uncovered.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$

Maxwell
505 
WWUS76 KSGX 130927
NPWSGX

URGENT - WEATHER MESSAGE
National Weather Service SAN DIEGO CA
227 AM PDT Wed Oct 13 2021

CAZ060-131600-
/O.CON.KSGX.FR.Y.0004.000000T0000Z-211013T1600Z/
Apple and Lucerne Valleys-
Including the cities of Hesperia and Apple Valley
227 AM PDT Wed Oct 13 2021

...FROST ADVISORY REMAINS IN EFFECT UNTIL 9 AM PDT THIS MORNING...

* WHAT...Temperatures 28 to 34 will result in frost.

* WHERE...Apple and Lucerne Valleys.

* WHEN...Until 9 AM PDT this morning.

* IMPACTS...Frost could kill sensitive outdoor vegetation if 
  left uncovered.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$

Nearby

Frost Advisories in California, 2021Every frost advisory in 2021

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.