Alert archive / California / Frost Advisories in 2021

Frost Advisory 33, NWS Eureka, CA

May 6, 2021Humboldt County, Mendocino County, Trinity County, California

NWS Eureka, CA issued this frost advisory at May 6, 2021, 3:11 AM PDT for Humboldt County, Mendocino County, Trinity County, California. It took effect at May 7, 2021, 3:00 AM PDT. It was in force for 5 hr.

The area

The counties it named.

The facts

Issued
May 6, 2021, 3:11 AM PDT (10:11 UTC)
In effect from
May 7, 2021, 3:00 AM PDT
Expired
May 7, 2021, 8:00 AM PDT
In force
5 hr
Issued by
NWS Eureka, CA

Counties Humboldt County, CA, Mendocino County, CA, Trinity County, CA

The radar

The Eureka (Bunker Hill) radar (KBHX), 73 km from the middle of the area, began a volume at 10:16 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, 10.2 hours before the alert went out and 241 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 2021-05-06Temperature 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 00:00Z on 2021-05-06The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 32 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
3550 m above ground
0-6 km bulk shear
27 kt
0-1 km storm-relative helicity
32 m²/s²
0-3 km storm-relative helicity
114 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

632 
WWUS76 KEKA 061011
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
311 AM PDT Thu May 6 2021

CAZ108-062230-
/O.NEW.KEKA.FR.Y.0033.210507T1000Z-210507T1500Z/
Southern Trinity-
311 AM PDT Thu May 6 2021

...FROST ADVISORY IN EFFECT FROM 3 AM TO 8 AM PDT FRIDAY...

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

* WHERE...Southern Trinity County.

* WHEN...From 3 AM to 8 AM PDT Friday.

* 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
222 
WWUS76 KEKA 062135
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
235 PM PDT Thu May 6 2021

CAZ106-111-070545-
/O.EXA.KEKA.FR.Y.0033.210507T1000Z-210507T1500Z/
Southern Humboldt Interior-Northeastern Mendocino Interior-
235 PM PDT Thu May 6 2021

...FROST ADVISORY IN EFFECT FROM 3 AM TO 8 AM PDT FRIDAY...

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

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

* WHEN...From 3 AM to 8 AM PDT Friday.

* 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.

&&

$$

CAZ108-070545-
/O.CON.KEKA.FR.Y.0033.210507T1000Z-210507T1500Z/
Southern Trinity-
235 PM PDT Thu May 6 2021

...FROST ADVISORY REMAINS IN EFFECT FROM 3 AM TO 8 AM PDT
FRIDAY...

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

* WHERE...Southern Trinity County.

* WHEN...From 3 AM to 8 AM PDT Friday.

* 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.

&&

$$
302 
WWUS76 KEKA 071049
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
349 AM PDT Fri May 7 2021

CAZ111-071200-
/O.CAN.KEKA.FR.Y.0033.000000T0000Z-210507T1500Z/
Northeastern Mendocino Interior-
349 AM PDT Fri May 7 2021

...FROST ADVISORY IS CANCELLED...

Breezy winds are keeping most areas in the upper 30s to mid 40s so
have cancelled the frost advisory. 

$$

CAZ106-108-071500-
/O.CON.KEKA.FR.Y.0033.000000T0000Z-210507T1500Z/
Southern Humboldt Interior-Southern Trinity-
349 AM PDT Fri May 7 2021

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

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

* WHERE...Southern Trinity and Southern Humboldt Interior 
  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.

&&

$$
687 
WWUS76 KEKA 071453
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
753 AM PDT Fri May 7 2021

CAZ106-108-071600-
/O.EXP.KEKA.FR.Y.0033.000000T0000Z-210507T1500Z/
Southern Humboldt Interior-Southern Trinity-
753 AM PDT Fri May 7 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
May 6, 3:00 AM PDTGale WarningEKA5 days
May 6, 3:00 AM PDTHazardous Seas WarningEKA54 hr
May 6, 8:44 AM PDTSmall Craft AdvisoryEKA33 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.