Alert archive / California / Frost Advisories in 2021

Frost Advisory 32, NWS Eureka, CA

April 26, 20215 counties in California

NWS Eureka, CA issued this frost advisory at Apr 26, 2021, 1:55 AM PDT for 5 counties in California. It took effect at Apr 27, 2021, 12:00 AM PDT. It was in force for 8 hr.

The area

The counties it named.

The facts

Issued
Apr 26, 2021, 1:55 AM PDT (08:55 UTC)
In effect from
Apr 27, 2021, 12:00 AM PDT
Expired
Apr 27, 2021, 8:00 AM PDT
In force
8 hr
Issued by
NWS Eureka, CA

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

The radar

The Eureka (Bunker Hill) radar (KBHX), 75 km from the middle of the area, began a volume at 08:55 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 00:00Z, 8.9 hours before the alert went out and 233 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 00:00Z on 2021-04-26Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCLLFCEL10008507005003002001001 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 00:00Z on 2021-04-26The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -2 square meters per square second.1939Sfc1 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
1399 m above ground
0-6 km bulk shear
29 kt
0-1 km storm-relative helicity
-2 m²/s²
0-3 km storm-relative helicity
-13 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

404 
WWUS76 KEKA 260855
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
155 AM PDT Mon Apr 26 2021

CAZ107-108-110-111-114-115-261700-
/O.NEW.KEKA.FR.Y.0032.210427T0700Z-210427T1500Z/
/O.CON.KEKA.FR.Y.0031.210426T1000Z-210426T1600Z/
Northern Trinity-Southern Trinity-Northwestern Mendocino Interior-
Northeastern Mendocino Interior-Northern Lake-Southern Lake-
155 AM PDT Mon Apr 26 2021

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

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

* WHAT...Clear skies and a cold airmass will lead to morning low 
  temperatures of 36 degrees or less. Frost formation is likely 
  across low elevation communities and surrounding valleys.
  

* WHERE...Northern Trinity, Southern Trinity, Northwestern 
  Mendocino Interior, Northeastern Mendocino Interior, Northern 
  Lake and Southern Lake Counties.

* WHEN...For the first Frost Advisory, until 9 AM PDT this 
  morning. For the second Frost Advisory, from midnight tonight 
  to 8 AM PDT Tuesday.

* 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.

&&

$$

CAZ102>106-109-112-113-261700-
/O.NEW.KEKA.FR.Y.0032.210427T0700Z-210427T1500Z/
Del Norte Interior-Northern Humboldt Coast-Southwestern Humboldt-
Northern Humboldt Interior-Southern Humboldt Interior-
Mendocino Coast-Southwestern Mendocino Interior-
Southeastern Mendocino Interior-
155 AM PDT Mon Apr 26 2021

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

* WHAT...Clear skies and a cold airmass will lead to morning low 
  temperatures of 36 degrees or less. Frost formation is likely 
  across low elevation communities and surrounding valleys.
 
* WHERE...Del Norte Interior, Northern Humboldt Coast, 
  Southwestern Humboldt, Northern Humboldt Interior, Southern 
  Humboldt Interior, Mendocino Coast, Southwestern Mendocino 
  Interior and Southeastern Mendocino Interior Counties.

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

* 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.

&&

$$
5 follow-up statements
108 
WWUS76 KEKA 261602
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
902 AM PDT Mon Apr 26 2021

CAZ107-108-110-111-114-115-262200-
/O.EXP.KEKA.FR.Y.0031.000000T0000Z-210426T1600Z/
/O.CON.KEKA.FR.Y.0032.210427T0700Z-210427T1500Z/
Northern Trinity-Southern Trinity-Northwestern Mendocino Interior-
Northeastern Mendocino Interior-Northern Lake-Southern Lake-
902 AM PDT Mon Apr 26 2021

...FROST ADVISORY REMAINS IN EFFECT FROM MIDNIGHT TONIGHT TO 8 AM
PDT TUESDAY...
...FROST ADVISORY FOR THIS MORNING HAS EXPIRED...

* WHAT...Temperatures as low as 32 will result in frost 
  formation.

* WHERE...Northern Trinity, Southern Trinity, Northwestern 
  Mendocino Interior, Northeastern Mendocino Interior, Northern 
  Lake and Southern Lake Counties.

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

* 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.

&&

$$

CAZ102>106-109-112-113-262200-
/O.CON.KEKA.FR.Y.0032.210427T0700Z-210427T1500Z/
Del Norte Interior-Northern Humboldt Coast-Southwestern Humboldt-
Northern Humboldt Interior-Southern Humboldt Interior-
Mendocino Coast-Southwestern Mendocino Interior-
Southeastern Mendocino Interior-
902 AM PDT Mon Apr 26 2021

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

* WHAT...Clear skies and a cold airmass will lead to morning low 
  temperatures of 36 degrees or less. Frost formation is likely 
  across low elevation communities and surrounding valleys.

* WHERE...Del Norte Interior, Northern Humboldt Coast,
  Southwestern Humboldt, Northern Humboldt Interior, Southern
  Humboldt Interior, Mendocino Coast, Southwestern Mendocino
  Interior and Southeastern Mendocino Interior.

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

* 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.

&&

$$
365 
WWUS76 KEKA 262110
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
210 PM PDT Mon Apr 26 2021

CAZ102-103-109-112-113-262215-
/O.CAN.KEKA.FR.Y.0032.210427T0700Z-210427T1500Z/
Del Norte Interior-Northern Humboldt Coast-Mendocino Coast-
Southwestern Mendocino Interior-Southeastern Mendocino Interior-
210 PM PDT Mon Apr 26 2021

...FROST ADVISORY IS CANCELLED...

Temperatures are expected to remain in the upper 30s in these
locations.

$$

CAZ107-108-111-114-270600-
/O.UPG.KEKA.FR.Y.0032.210427T0700Z-210427T1500Z/
/O.NEW.KEKA.FZ.W.0017.210427T0700Z-210427T1500Z/
Northern Trinity-Southern Trinity-Northeastern Mendocino Interior-
Northern Lake-
210 PM PDT Mon Apr 26 2021

...FREEZE WARNING IN EFFECT FROM MIDNIGHT TONIGHT TO 8 AM PDT
TUESDAY...

* WHAT...Sub-freezing temperatures as low as 30 expected.

* WHERE...Northern Trinity, Southern Trinity, Northeastern
  Mendocino Interior and Northern Lake County.

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

* IMPACTS...Frost and freeze conditions will kill crops and other
  sensitive vegetation.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold. Provide
adequate shelter for outdoor pets or consider bringing them
indoors.

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.

&&

$$

CAZ104>106-110-115-270600-
/O.CON.KEKA.FR.Y.0032.210427T0700Z-210427T1500Z/
Southwestern Humboldt-Northern Humboldt Interior-
Southern Humboldt Interior-Northwestern Mendocino Interior-
Southern Lake-
210 PM PDT Mon Apr 26 2021

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

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

* WHERE...Northwestern Mendocino Interior, Northern Humboldt
  Interior, Southwestern Humboldt, Southern Humboldt Interior and
  Southern Lake County.

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

* 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.

&&

$$
716 
WWUS76 KEKA 270525
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
1025 PM PDT Mon Apr 26 2021

CAZ107-108-111-114-271245-
/O.CON.KEKA.FZ.W.0017.210427T0700Z-210427T1500Z/
Northern Trinity-Southern Trinity-Northeastern Mendocino Interior-
Northern Lake-
1025 PM PDT Mon Apr 26 2021

...FREEZE WARNING REMAINS IN EFFECT UNTIL 8 AM PDT TUESDAY...

* WHAT...Sub-freezing temperatures as low as 30 expected.

* WHERE...Northern Trinity, Southern Trinity, Northeastern 
  Mendocino Interior and Northern Lake County.

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

* IMPACTS...Frost and freeze conditions will kill crops and 
  other sensitive vegetation.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold. Provide
adequate shelter for outdoor pets or consider bringing them
indoors.

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.

&&

$$

CAZ104>106-110-115-271245-
/O.CON.KEKA.FR.Y.0032.210427T0700Z-210427T1500Z/
Southwestern Humboldt-Northern Humboldt Interior-
Southern Humboldt Interior-Northwestern Mendocino Interior-
Southern Lake-
1025 PM PDT Mon Apr 26 2021

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

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

* WHERE...Northwestern Mendocino Interior, Northern Humboldt 
  Interior, Southwestern Humboldt, Southern Humboldt Interior 
  and Southern Lake County.

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

* 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.

&&

$$
243 
WWUS76 KEKA 271020
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
320 AM PDT Tue Apr 27 2021

CAZ107-108-111-114-271500-
/O.CON.KEKA.FZ.W.0017.000000T0000Z-210427T1500Z/
Northern Trinity-Southern Trinity-Northeastern Mendocino Interior-
Northern Lake-
320 AM PDT Tue Apr 27 2021

...FREEZE WARNING REMAINS IN EFFECT UNTIL 8 AM PDT THIS MORNING...

* WHAT...Sub-freezing temperatures as low as 26.

* WHERE...Southern Trinity, Northeastern Mendocino Interior, 
  Northern Trinity and Northern Lake Counties.

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

* IMPACTS...Frost and freeze conditions will kill crops and 
  other sensitive vegetation.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold. Provide
adequate shelter for outdoor pets or consider bringing them
indoors.

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.

&&

$$

CAZ104>106-110-115-271500-
/O.CON.KEKA.FR.Y.0032.000000T0000Z-210427T1500Z/
Southwestern Humboldt-Northern Humboldt Interior-
Southern Humboldt Interior-Northwestern Mendocino Interior-
Southern Lake-
320 AM PDT Tue Apr 27 2021

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

* WHAT...Temperatures as low as 32 will result in frost 
  formation.

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

* WHEN...Until 8 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.

&&

$$
414 
WWUS76 KEKA 271445
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
745 AM PDT Tue Apr 27 2021

CAZ107-108-111-114-271545-
/O.EXP.KEKA.FZ.W.0017.000000T0000Z-210427T1500Z/
Northern Trinity-Southern Trinity-Northeastern Mendocino Interior-
Northern Lake-
745 AM PDT Tue Apr 27 2021

...FREEZE WARNING WILL EXPIRE AT 8 AM PDT THIS MORNING...

$$

CAZ104>106-110-115-271545-
/O.EXP.KEKA.FR.Y.0032.000000T0000Z-210427T1500Z/
Southwestern Humboldt-Northern Humboldt Interior-
Southern Humboldt Interior-Northwestern Mendocino Interior-
Southern Lake-
745 AM PDT Tue Apr 27 2021

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

$$

The office that day

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

IssuedProductOfficeCountiesLasted
Apr 25, 10:34 PM PDTFrost AdvisoryEKALake, Mendocino, Trinity10 hr
Apr 26, 2:10 PM PDTFreeze WarningEKALake, Mendocino, Trinity18 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.