Alert archive / California / Frost Advisories in 2021

Frost Advisory 29, NWS Eureka, CA

April 14, 20215 counties in California

NWS Eureka, CA issued this frost advisory at Apr 14, 2021, 2:50 PM PDT for 5 counties in California. It took effect at Apr 15, 2021, 1:00 AM PDT. It was in force for 8 hr.

The area

The counties it named.

The facts

Issued
Apr 14, 2021, 2:50 PM PDT (21:50 UTC)
In effect from
Apr 15, 2021, 1:00 AM PDT
Expired
Apr 15, 2021, 9:00 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 21:54 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, 9.8 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 12:00Z on 2021-04-14Temperature 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 2021-04-14The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 9 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
2573 m above ground
0-6 km bulk shear
36 kt
0-1 km storm-relative helicity
9 m²/s²
0-3 km storm-relative helicity
49 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

779 
WWUS76 KEKA 142150
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
250 PM PDT Wed Apr 14 2021

CAZ103>112-114-115-150600-
/O.NEW.KEKA.FR.Y.0029.210415T0800Z-210415T1600Z/
Northern Humboldt Coast-Southwestern Humboldt-
Northern Humboldt Interior-Southern Humboldt Interior-
Northern Trinity-Southern Trinity-Mendocino Coast-
Northwestern Mendocino Interior-Northeastern Mendocino Interior-
Southwestern Mendocino Interior-Northern Lake-Southern Lake-
250 PM PDT Wed Apr 14 2021

...FROST ADVISORY IN EFFECT FROM 1 AM TO 9 AM PDT THURSDAY...

* WHAT...Temperatures as low as 31 will result in frost 
  formation.

* WHERE...Portions of northwest California.

* WHEN...From 1 AM to 9 AM PDT Thursday.

* 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
019 
WWUS76 KEKA 150551
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
1051 PM PDT Wed Apr 14 2021

CAZ103>112-114-115-151600-
/O.CON.KEKA.FR.Y.0029.210415T0800Z-210415T1600Z/
Northern Humboldt Coast-Southwestern Humboldt-
Northern Humboldt Interior-Southern Humboldt Interior-
Northern Trinity-Southern Trinity-Mendocino Coast-
Northwestern Mendocino Interior-Northeastern Mendocino Interior-
Southwestern Mendocino Interior-Northern Lake-Southern Lake-
1051 PM PDT Wed Apr 14 2021

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

* WHAT...Temperatures as low as 31 will result in frost 
  formation.

* WHERE...Portions of northwest California.

* WHEN...From 1 AM to 9 AM PDT Thursday.

* 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.

&&

$$
624 
WWUS76 KEKA 151007
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
307 AM PDT Thu Apr 15 2021

CAZ101-151600-
/O.EXA.KEKA.FR.Y.0029.000000T0000Z-210415T1600Z/
Coastal Del Norte-
307 AM PDT Thu Apr 15 2021

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

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

* WHERE...Coastal Del Norte County.

* 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.

&&

$$

CAZ103>112-114-115-151600-
/O.CON.KEKA.FR.Y.0029.000000T0000Z-210415T1600Z/
Northern Humboldt Coast-Southwestern Humboldt-
Northern Humboldt Interior-Southern Humboldt Interior-
Northern Trinity-Southern Trinity-Mendocino Coast-
Northwestern Mendocino Interior-Northeastern Mendocino Interior-
Southwestern Mendocino Interior-Northern Lake-Southern Lake-
307 AM PDT Thu Apr 15 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.

&&

$$
815 
WWUS76 KEKA 151551
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
851 AM PDT Thu Apr 15 2021

CAZ101-103>112-114-115-151700-
/O.EXP.KEKA.FR.Y.0029.000000T0000Z-210415T1600Z/
Coastal Del Norte-Northern Humboldt Coast-Southwestern Humboldt-
Northern Humboldt Interior-Southern Humboldt Interior-
Northern Trinity-Southern Trinity-Mendocino Coast-
Northwestern Mendocino Interior-Northeastern Mendocino Interior-
Southwestern Mendocino Interior-Northern Lake-Southern Lake-
851 AM PDT Thu Apr 15 2021

...FROST ADVISORY WILL EXPIRE AT 9 AM PDT THIS MORNING...


$$

The office that day

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

IssuedProductOfficeCountiesLasted
Apr 13, 8:13 PM PDTSmall Craft AdvisoryEKA10 hr
Apr 14, 5:50 AM PDTSmall Craft AdvisoryEKA30 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.