Alert archive / California / Frost Advisories in 2025

Frost Advisory 13, NWS Eureka, CA

April 20, 2025Trinity County, California

NWS Eureka, CA issued this frost advisory at Apr 20, 2025, 2:28 AM PDT for Trinity County, California. It took effect at Apr 21, 2025, 4:00 AM PDT. It was in force for 4 hr.

The area

The counties it named.

The facts

Issued
Apr 20, 2025, 2:28 AM PDT (09:28 UTC)
In effect from
Apr 21, 2025, 4:00 AM PDT
Expired
Apr 21, 2025, 8:00 AM PDT
In force
4 hr
Issued by
NWS Eureka, CA

County Trinity County, CA

The radar

The Eureka (Bunker Hill) radar (KBHX), 101 km from the middle of the area, began a volume at 09:26 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, 9.5 hours before the alert went out and 193 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 2025-04-20Temperature 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 2025-04-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 3 square meters per square second.19395878Sfc1 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
2267 m above ground
0-6 km bulk shear
32 kt
0-1 km storm-relative helicity
3 m²/s²
0-3 km storm-relative helicity
40 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

149 
WWUS76 KEKA 200928
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
228 AM PDT Sun Apr 20 2025

CAZ107-108-202100-
/O.NEW.KEKA.FR.Y.0013.250421T0900Z-250421T1600Z/
Northern Trinity-Southern Trinity-
Including Weaverville, Peanut, Forest Glen, and Hayfork
228 AM PDT Sun Apr 20 2025

...FROST ADVISORY IN EFFECT FROM 2 AM TO 9 AM PDT MONDAY...

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

* WHERE...Trinity County.

* WHEN...From 2 AM to 9 AM PDT Monday.

* IMPACTS...Frost could harm sensitive outdoor vegetation. Sensitive 
  outdoor plants may be killed if left uncovered.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$

For hazard areas see https://www.wrh.noaa.gov/map/?wfo=eka

JJW
3 follow-up statements
262 
WWUS76 KEKA 202032
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
132 PM PDT Sun Apr 20 2025

CAZ107-108-211115-
/O.EXT.KEKA.FR.Y.0013.250421T1100Z-250421T1500Z/
Northern Trinity-Southern Trinity-
Including Forest Glen, Hayfork, Weaverville, and Peanut
132 PM PDT Sun Apr 20 2025

...FROST ADVISORY NOW IN EFFECT FROM 4 AM TO 8 AM PDT MONDAY...

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

* WHERE...Trinity County.

* WHEN...From 4 AM to 8 AM PDT Monday.

* IMPACTS...Frost could harm sensitive outdoor vegetation. Sensitive 
  outdoor plants may be killed if left uncovered.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$

For hazard areas see https://www.wrh.noaa.gov/map/?wfo=eka

DB
232 
WWUS76 KEKA 211003
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
303 AM PDT Mon Apr 21 2025

CAZ107-108-211500-
/O.CON.KEKA.FR.Y.0013.250421T1100Z-250421T1500Z/
Northern Trinity-Southern Trinity-
Including Weaverville, Forest Glen, Hayfork, and Peanut
303 AM PDT Mon Apr 21 2025

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

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

* WHERE...Trinity County.

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

* IMPACTS...Frost could harm sensitive outdoor vegetation. Sensitive 
  outdoor plants may be killed if left uncovered.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$

For hazard areas see https://www.wrh.noaa.gov/map/?wfo=eka

EYS
788 
WWUS76 KEKA 211451
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
751 AM PDT Mon Apr 21 2025

CAZ107-108-211600-
/O.EXP.KEKA.FR.Y.0013.000000T0000Z-250421T1500Z/
Northern Trinity-Southern Trinity-
Including Forest Glen, Weaverville, Hayfork, and Peanut
751 AM PDT Mon Apr 21 2025

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

$$

For hazard areas see https://www.wrh.noaa.gov/map/?wfo=eka

MKK

Nearby

Frost Advisories in California, 2025Every frost advisory in 2025

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.