Alert archive / California / Frost Advisories in 2023

Frost Advisory 21, NWS Eureka, CA

June 20, 2023Humboldt County, Trinity County, California

NWS Eureka, CA issued this frost advisory at Jun 20, 2023, 2:11 PM PDT for Humboldt County, Trinity County, California. It took effect at Jun 21, 2023, 5:00 AM PDT. It was in force for 4 hr.

The area

The counties it named.

The facts

Issued
Jun 20, 2023, 2:11 PM PDT (21:11 UTC)
In effect from
Jun 21, 2023, 5:00 AM PDT
Expired
Jun 21, 2023, 9:00 AM PDT
In force
4 hr
Issued by
NWS Eureka, CA

Counties Humboldt County, CA, Trinity County, CA

The radar

The Eureka (Bunker Hill) radar (KBHX), 69 km from the middle of the area, began a volume at 21:11 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, 9.2 hours before the alert went out and 197 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 2023-06-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 49 joules per kilogram.LCLEL10008507005003002001001 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 2023-06-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 18 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
49 J/kg
Mixed-layer CIN
0 J/kg
Mixed-layer LCL
479 m above ground
0-6 km bulk shear
22 kt
0-1 km storm-relative helicity
18 m²/s²
0-3 km storm-relative helicity
52 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

671 
WWUS76 KEKA 202111
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
211 PM PDT Tue Jun 20 2023

CAZ106-108-210515-
/O.NEW.KEKA.FR.Y.0021.230621T1200Z-230621T1600Z/
Southern Humboldt Interior-Southern Trinity-
211 PM PDT Tue Jun 20 2023

...FROST ADVISORY IN EFFECT FROM 5 AM TO 9 AM PDT WEDNESDAY...

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

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

* WHEN...From 5 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.

&&

$$
2 follow-up statements
111 
WWUS76 KEKA 210524
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
1024 PM PDT Tue Jun 20 2023

CAZ106-108-211330-
/O.CON.KEKA.FR.Y.0021.230621T1200Z-230621T1600Z/
Southern Humboldt Interior-Southern Trinity-
1024 PM PDT Tue Jun 20 2023

...FROST ADVISORY REMAINS IN EFFECT FROM 5 AM TO 9 AM PDT
WEDNESDAY...

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

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

* WHEN...From 5 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.

&&

$$
175 
WWUS76 KEKA 211336
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
636 AM PDT Wed Jun 21 2023

CAZ106-108-211600-
/O.CON.KEKA.FR.Y.0021.000000T0000Z-230621T1600Z/
Southern Humboldt Interior-Southern Trinity-
636 AM PDT Wed Jun 21 2023

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

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

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

* WHEN...From 5 AM to 9 AM Wednesday.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

$$

The office that day

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

IssuedProductOfficeCountiesLasted
Jun 20, 2:42 PM PDTSmall Craft AdvisoryEKA48 hr

Nearby

Frost Advisories in California, 2023Every frost advisory in 2023

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.