Alert archive / California / Frost Advisories in 2021

Frost Advisory 25, NWS Eureka, CA

April 9, 2021Del Norte County, Humboldt County, Mendocino County, California

NWS Eureka, CA issued this frost advisory at Apr 9, 2021, 2:20 PM PDT for Del Norte County, Humboldt County, Mendocino County, California. It took effect at Apr 10, 2021, 12:00 AM PDT. It was in force for 9 hr.

The area

The counties it named.

The facts

Issued
Apr 9, 2021, 2:20 PM PDT (21:20 UTC)
In effect from
Apr 10, 2021, 12:00 AM PDT
Expired
Apr 10, 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 21:19 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, 9.3 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 2021-04-09Temperature 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 2021-04-09The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -5 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
1035 m above ground
0-6 km bulk shear
19 kt
0-1 km storm-relative helicity
-5 m²/s²
0-3 km storm-relative helicity
22 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

947 
WWUS76 KEKA 092120
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
220 PM PDT Fri Apr 9 2021

CAZ102-104>106-110>112-100530-
/O.NEW.KEKA.FR.Y.0025.210410T0700Z-210410T1600Z/
Del Norte Interior-Southwestern Humboldt-
Northern Humboldt Interior-Southern Humboldt Interior-
Northwestern Mendocino Interior-Northeastern Mendocino Interior-
Southwestern Mendocino Interior-
220 PM PDT Fri Apr 9 2021

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

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

* WHERE...Del Norte Interior, Humboldt Interior, Northwestern
  Mendocino Interior, Northeastern Mendocino Interior and
  Southwestern Mendocino Interior counties.

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

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

$$
4 follow-up statements
128 
WWUS76 KEKA 092231
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
331 PM PDT Fri Apr 9 2021

CAZ101-109-113-100645-
/O.EXA.KEKA.FR.Y.0025.210410T0700Z-210410T1600Z/
Coastal Del Norte-Mendocino Coast-Southeastern Mendocino Interior-
331 PM PDT Fri Apr 9 2021

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

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

* WHERE...Coastal Del Norte, Mendocino Coast and Southeastern 
  Mendocino Interior Counties.

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

* 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.

&&

$$

CAZ102-104>106-110>112-100645-
/O.CON.KEKA.FR.Y.0025.210410T0700Z-210410T1600Z/
Del Norte Interior-Southwestern Humboldt-
Northern Humboldt Interior-Southern Humboldt Interior-
Northwestern Mendocino Interior-Northeastern Mendocino Interior-
Southwestern Mendocino Interior-
331 PM PDT Fri Apr 9 2021

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

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

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

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

* 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.

&&

$$
455 
WWUS76 KEKA 100421
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
921 PM PDT Fri Apr 9 2021

CAZ101-102-104>106-109>113-101230-
/O.CON.KEKA.FR.Y.0025.210410T0700Z-210410T1600Z/
Coastal Del Norte-Del Norte Interior-Southwestern Humboldt-
Northern Humboldt Interior-Southern Humboldt Interior-
Mendocino Coast-Northwestern Mendocino Interior-
Northeastern Mendocino Interior-Southwestern Mendocino Interior-
Southeastern Mendocino Interior-
921 PM PDT Fri Apr 9 2021

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

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

* WHERE...Portions of northwest California.

* WHEN...Until 9 AM PDT Saturday.

* 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.

&&

$$
325 
WWUS76 KEKA 100954
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
254 AM PDT Sat Apr 10 2021

CAZ101-102-104>106-109>113-101600-
/O.CON.KEKA.FR.Y.0025.000000T0000Z-210410T1600Z/
Coastal Del Norte-Del Norte Interior-Southwestern Humboldt-
Northern Humboldt Interior-Southern Humboldt Interior-
Mendocino Coast-Northwestern Mendocino Interior-
Northeastern Mendocino Interior-Southwestern Mendocino Interior-
Southeastern Mendocino Interior-
254 AM PDT Sat Apr 10 2021

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

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

* WHERE...Portions of northwest California.

* 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.

&&

$$
950 
WWUS76 KEKA 101612
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
912 AM PDT Sat Apr 10 2021

CAZ101-102-104>106-109>113-101715-
/O.EXP.KEKA.FR.Y.0025.000000T0000Z-210410T1600Z/
Coastal Del Norte-Del Norte Interior-Southwestern Humboldt-
Northern Humboldt Interior-Southern Humboldt Interior-
Mendocino Coast-Northwestern Mendocino Interior-
Northeastern Mendocino Interior-Southwestern Mendocino Interior-
Southeastern Mendocino Interior-
912 AM PDT Sat Apr 10 2021

...FROST ADVISORY HAS EXPIRED...

More frost is expected tonight and Sunday morning.

$$

The office that day

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

IssuedProductOfficeCountiesLasted
Apr 9, 2:52 AM PDTGale WarningEKA5 days

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.