Alert archive / California / Frost Advisories in 2021

Frost Advisory 27, NWS Eureka, CA

April 11, 2021Del Norte County, Humboldt County, Mendocino County, California

NWS Eureka, CA issued this frost advisory at Apr 11, 2021, 2:21 PM PDT for Del Norte County, Humboldt County, Mendocino County, California. It took effect at Apr 12, 2021, 12:00 AM PDT. It was in force for 9 hr.

The area

The counties it named.

The facts

Issued
Apr 11, 2021, 2:21 PM PDT (21:21 UTC)
In effect from
Apr 12, 2021, 12:00 AM PDT
Expired
Apr 12, 2021, 9:00 AM PDT
In force
9 hr
Issued by
NWS Eureka, CA

Counties Del Norte County, CA, Humboldt County, CA, Mendocino County, CA

The radar

The Eureka (Bunker Hill) radar (KBHX), 47 km from the middle of the area, began a volume at 21:20 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, 9.4 hours before the alert went out and 210 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 2021-04-11Temperature 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 2021-04-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -5 square meters per square second.193958Sfc1 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
822 m above ground
0-6 km bulk shear
39 kt
0-1 km storm-relative helicity
-5 m²/s²
0-3 km storm-relative helicity
35 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

417 
WWUS76 KEKA 112121
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
221 PM PDT Sun Apr 11 2021

CAZ103>106-109>111-120530-
/O.NEW.KEKA.FR.Y.0027.210412T0700Z-210412T1600Z/
Northern Humboldt Coast-Southwestern Humboldt-
Northern Humboldt Interior-Southern Humboldt Interior-
Mendocino Coast-Northwestern Mendocino Interior-
Northeastern Mendocino Interior-
221 PM PDT Sun Apr 11 2021

...FROST ADVISORY IN EFFECT FROM MIDNIGHT TONIGHT TO 9 AM MONDAY...

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

* WHERE...Humboldt County, Mendocino Coast, Northwestern Mendocino
  Interior, and Northeastern Mendocino Interior.

* WHEN...From midnight tonight to 9 AM Monday.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

$$
3 follow-up statements
550 
WWUS76 KEKA 120329
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
829 PM PDT Sun Apr 11 2021

CAZ102-121130-
/O.EXA.KEKA.FR.Y.0027.210412T0700Z-210412T1600Z/
Del Norte Interior-
829 PM PDT Sun Apr 11 2021

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

* WHAT...Temperatures as low as 36 will result in frost 
  formation.

* WHERE...Del Norte Interior County.

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

* 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.

&&

$$

CAZ103>106-109>111-121130-
/O.CON.KEKA.FR.Y.0027.210412T0700Z-210412T1600Z/
Northern Humboldt Coast-Southwestern Humboldt-
Northern Humboldt Interior-Southern Humboldt Interior-
Mendocino Coast-Northwestern Mendocino Interior-
Northeastern Mendocino Interior-
829 PM PDT Sun Apr 11 2021

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

* WHAT...Temperatures as low as 36 will result in frost 
  formation.

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

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

* 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.

&&

$$
183 
WWUS76 KEKA 120854
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
154 AM PDT Mon Apr 12 2021

CAZ102>106-109>111-121600-
/O.CON.KEKA.FR.Y.0027.000000T0000Z-210412T1600Z/
Del Norte Interior-Northern Humboldt Coast-Southwestern Humboldt-
Northern Humboldt Interior-Southern Humboldt Interior-
Mendocino Coast-Northwestern Mendocino Interior-
Northeastern Mendocino Interior-
154 AM PDT Mon Apr 12 2021

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

* WHAT...Temperatures as low as 34 will result in frost 
  formation.

* WHERE...Portions of Mendocino, Humboldt, and Del Norte 
  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.

&&

$$
946 
WWUS76 KEKA 121603
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
903 AM PDT Mon Apr 12 2021

CAZ102>106-109>111-121715-
/O.EXP.KEKA.FR.Y.0027.000000T0000Z-210412T1600Z/
Del Norte Interior-Northern Humboldt Coast-Southwestern Humboldt-
Northern Humboldt Interior-Southern Humboldt Interior-
Mendocino Coast-Northwestern Mendocino Interior-
Northeastern Mendocino Interior-
903 AM PDT Mon Apr 12 2021

...FROST ADVISORY HAS EXPIRED...


$$

The office that day

Everything else NWS Eureka, CA issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 11, 2:14 PM PDTHazardous Seas WarningEKA67 hr

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.