Alert archive / California / Frost Advisories in 2021

Frost Advisory 28, NWS Eureka, CA

April 13, 2021Humboldt County, Mendocino County, California

NWS Eureka, CA issued this frost advisory at Apr 13, 2021, 2:46 PM PDT for Humboldt County, Mendocino County, California. It took effect at Apr 14, 2021, 3:00 AM PDT. It was in force for 6 hr.

The area

The counties it named.

The facts

Issued
Apr 13, 2021, 2:46 PM PDT (21:46 UTC)
In effect from
Apr 14, 2021, 3:00 AM PDT
Expired
Apr 14, 2021, 9:00 AM PDT
In force
6 hr
Issued by
NWS Eureka, CA

Counties Humboldt County, CA, Mendocino County, CA

The radar

The Eureka (Bunker Hill) radar (KBHX), 71 km from the middle of the area, began a volume at 21:46 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

Medford/Jackson, OR (KMFR), launched 12:00Z, 9.8 hours before the alert went out and 266 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, Medford/Jackson, OR at 12:00Z on 2021-04-13Temperature 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, Medford/Jackson, OR at 12:00Z on 2021-04-13The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -2 square meters per square second.1939587897Sfc1 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
1758 m above ground
0-6 km bulk shear
39 kt
0-1 km storm-relative helicity
-2 m²/s²
0-3 km storm-relative helicity
53 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

824 
WWUS76 KEKA 132146
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
246 PM PDT Tue Apr 13 2021

CAZ106-111-140600-
/O.NEW.KEKA.FR.Y.0028.210414T1000Z-210414T1600Z/
Southern Humboldt Interior-Northeastern Mendocino Interior-
246 PM PDT Tue Apr 13 2021

...FROST ADVISORY IN EFFECT FROM 3 AM TO 9 AM PDT WEDNESDAY...

* WHAT...Temperatures as low as 35 will result in frost 
  formation.

* WHERE...Southern Humboldt Interior and Northeastern Mendocino 
  Interior Counties.

* WHEN...From 3 AM 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.

Frost Advisories and Freeze Warnings are issued during the local
growing season as defined by climatology and local agriculture
experts. Once the growing season has ended these statements will
no longer be issued until the spring.

&&

$$
3 follow-up statements
629 
WWUS76 KEKA 140328
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
828 PM PDT Tue Apr 13 2021

CAZ111-140430-
/O.CAN.KEKA.FR.Y.0028.210414T1000Z-210414T1600Z/
Northeastern Mendocino Interior-
828 PM PDT Tue Apr 13 2021

...FROST ADVISORY IS CANCELLED...


$$

CAZ106-141130-
/O.CON.KEKA.FR.Y.0028.210414T1000Z-210414T1600Z/
Southern Humboldt Interior-
828 PM PDT Tue Apr 13 2021

...FROST ADVISORY REMAINS IN EFFECT FROM 3 AM TO 9 AM PDT
WEDNESDAY...

* WHAT...Temperatures as low as 35 will result in frost 
  formation.

* WHERE...Southern Humboldt Interior County.

* WHEN...From 3 AM 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.

Frost Advisories and Freeze Warnings are issued during the local
growing season as defined by climatology and local agriculture
experts. Once the growing season has ended these statements will
no longer be issued until the spring.

&&

$$
747 
WWUS76 KEKA 140936
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
236 AM PDT Wed Apr 14 2021

CAZ103-104-110-141600-
/O.EXA.KEKA.FR.Y.0028.210414T1000Z-210414T1600Z/
Northern Humboldt Coast-Southwestern Humboldt-
Northwestern Mendocino Interior-
236 AM PDT Wed Apr 14 2021

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

* WHAT...Temperatures as low as 33 will result in frost 
  formation.

* WHERE...Northern Humboldt Coast, Southwestern Humboldt and 
  Northwestern Mendocino Interior Counties.

* 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.

Frost Advisories and Freeze Warnings are issued during the local
growing season as defined by climatology and local agriculture
experts. Once the growing season has ended these statements will
no longer be issued until the spring.

&&

$$

CAZ106-141600-
/O.CON.KEKA.FR.Y.0028.210414T1000Z-210414T1600Z/
Southern Humboldt Interior-
236 AM PDT Wed Apr 14 2021

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

* WHAT...Temperatures as low as 33 will result in frost 
  formation.

* WHERE...Southern Humboldt Interior County.

* 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.

Frost Advisories and Freeze Warnings are issued during the local
growing season as defined by climatology and local agriculture
experts. Once the growing season has ended these statements will
no longer be issued until the spring.

&&

$$
992 
WWUS76 KEKA 141547
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
847 AM PDT Wed Apr 14 2021

CAZ103-104-106-110-141700-
/O.EXP.KEKA.FR.Y.0028.000000T0000Z-210414T1600Z/
Northern Humboldt Coast-Southwestern Humboldt-
Southern Humboldt Interior-Northwestern Mendocino Interior-
847 AM PDT Wed Apr 14 2021

...FROST ADVISORY WILL EXPIRE AT 9 AM PDT THIS MORNING...

$$

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.