Alert archive / California / Freeze Watches in 2021

Freeze Watch 4, NWS Eureka, CA

March 29, 2021Lake County, Mendocino County, California

NWS Eureka, CA issued this freeze watch at Mar 29, 2021, 3:51 AM PDT for Lake County, Mendocino County, California. It took effect at Mar 29, 2021, 11:00 PM PDT. It was in force for .

The area

The counties it named.

The facts

Issued
Mar 29, 2021, 3:51 AM PDT (10:51 UTC)
In effect from
Mar 29, 2021, 11:00 PM PDT
Expired
Mar 29, 2021, 2:24 PM PDT
In force
Issued by
NWS Eureka, CA

Counties Lake County, CA, Mendocino County, CA

The radar

The Beale AFB radar (KBBX), 128 km from the middle of the area, began a volume at 10:57 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

Oakland, CA (KOAK), launched 00:00Z, 10.9 hours before the alert went out and 188 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, Oakland, CA at 00:00Z on 2021-03-29Temperature 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, Oakland, CA at 00:00Z on 2021-03-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 24 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
3471 m above ground
0-6 km bulk shear
24 kt
0-1 km storm-relative helicity
24 m²/s²
0-3 km storm-relative helicity
45 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

321 
WWUS76 KEKA 291051
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
351 AM PDT Mon Mar 29 2021

CAZ110-111-114-115-291900-
/O.NEW.KEKA.FZ.A.0004.210330T0600Z-210330T1500Z/
/O.CON.KEKA.FR.Y.0019.000000T0000Z-210329T1600Z/
Northwestern Mendocino Interior-Northeastern Mendocino Interior-
Northern Lake-Southern Lake-
351 AM PDT Mon Mar 29 2021

...FROST ADVISORY REMAINS IN EFFECT UNTIL 9 AM PDT THIS MORNING...
...FREEZE WATCH IN EFFECT FROM THIS EVENING THROUGH TUESDAY
MORNING...

* WHAT...For the Frost Advisory, temperatures as low as 32 will 
  result in frost formation. For the Freeze Watch, sub-freezing 
  temperatures as low as 29 possible.

* WHERE...Northwestern Mendocino Interior, Northeastern 
  Mendocino Interior, Northern Lake and Southern Lake Counties.

* WHEN...For the Frost Advisory, until 9 AM PDT this morning. 
  For the Freeze Watch, from this evening through Tuesday 
  morning.

* IMPACTS...Frost and freeze conditions could kill crops and 
  other sensitive vegetation.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold. Provide
adequate shelter for outdoor pets or consider bringing them
indoors.

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.

&&

$$

CAZ112-113-291600-
/O.CON.KEKA.FR.Y.0019.000000T0000Z-210329T1600Z/
Southwestern Mendocino Interior-Southeastern Mendocino Interior-
351 AM PDT Mon Mar 29 2021

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

* WHAT...Temperatures as low as 36 will result in frost 
  formation.

* WHERE...Southwestern Mendocino Interior and Southeastern 
  Mendocino Interior Counties.

* 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.

&&

$$
2 follow-up statements
159 
WWUS76 KEKA 291545
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
845 AM PDT Mon Mar 29 2021

CAZ110-111-114-115-292345-
/O.EXP.KEKA.FR.Y.0019.000000T0000Z-210329T1600Z/
/O.CON.KEKA.FZ.A.0004.210330T0600Z-210330T1500Z/
Northwestern Mendocino Interior-Northeastern Mendocino Interior-
Northern Lake-Southern Lake-
845 AM PDT Mon Mar 29 2021

...FREEZE WATCH REMAINS IN EFFECT FROM THIS EVENING THROUGH
TUESDAY MORNING...
...FROST ADVISORY WILL EXPIRE AT 9 AM PDT THIS MORNING...

* WHAT...Sub-freezing temperatures as low as 29 possible.

* WHERE...Northwestern Mendocino Interior, Northeastern 
  Mendocino Interior, Northern Lake and Southern Lake Counties.

* WHEN...From this evening through Tuesday morning.

* IMPACTS...Frost and freeze conditions could kill crops and 
  other sensitive vegetation.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold. Provide
adequate shelter for outdoor pets or consider bringing them
indoors.

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.

&&

$$

CAZ112-113-291645-
/O.EXP.KEKA.FR.Y.0019.000000T0000Z-210329T1600Z/
Southwestern Mendocino Interior-Southeastern Mendocino Interior-
845 AM PDT Mon Mar 29 2021

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


$$
927 
WWUS76 KEKA 292124
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
224 PM PDT Mon Mar 29 2021

CAZ110-111-114-300530-
/O.UPG.KEKA.FZ.A.0004.210330T0600Z-210330T1500Z/
/O.NEW.KEKA.FZ.W.0016.210330T0800Z-210330T1600Z/
Northwestern Mendocino Interior-Northeastern Mendocino Interior-
Northern Lake-
224 PM PDT Mon Mar 29 2021

...FREEZE WARNING IN EFFECT FROM 1 AM TO 9 AM PDT TUESDAY...

* WHAT...Sub-freezing temperatures as low as 29 expected.

* WHERE...Northwestern Mendocino Interior, Northeastern 
  Mendocino Interior and Northern Lake Counties.

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

* IMPACTS...Frost and freeze conditions will kill crops and 
  other sensitive vegetation.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold. Provide
adequate shelter for outdoor pets or consider bringing them
indoors.

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.

&&

$$

CAZ103-112-300530-
/O.NEW.KEKA.FZ.W.0016.210330T0800Z-210330T1600Z/
Northern Humboldt Coast-Southwestern Mendocino Interior-
224 PM PDT Mon Mar 29 2021

...FREEZE WARNING IN EFFECT FROM 1 AM TO 9 AM PDT TUESDAY...

* WHAT...Sub-freezing temperatures in the low 30s expected.

* WHERE...Sheltered portions of the Northern Humboldt Coast and
  Southwestern Mendocino Interior.

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

* IMPACTS...Frost and freeze conditions will kill crops and 
  other sensitive vegetation.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold. Provide
adequate shelter for outdoor pets or consider bringing them
indoors.

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.

&&

$$

CAZ115-300530-
/O.UPG.KEKA.FZ.A.0004.210330T0600Z-210330T1500Z/
/O.NEW.KEKA.FR.Y.0020.210330T0800Z-210330T1600Z/
Southern Lake-
224 PM PDT Mon Mar 29 2021

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

* WHAT...Temperatures in the low to mid 30s will result in frost 
  formation.

* WHERE...Southern Lake County.

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

* 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.

&&

$$

CAZ101-109-113-300530-
/O.NEW.KEKA.FR.Y.0020.210330T0800Z-210330T1600Z/
Coastal Del Norte-Mendocino Coast-Southeastern Mendocino Interior-
224 PM PDT Mon Mar 29 2021

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

* WHAT...Temperatures in the low to mid 30s will result in frost 
  formation.

* WHERE...Sheltered inland portions of Coastal Del Norte,
  Mendocino Coast and much of the Southeastern Mendocino County
  Interior.

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

* 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.

&&

$$

The office that day

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

IssuedProductOfficeCountiesLasted
Mar 29, 2:24 PM PDTFrost AdvisoryEKADel Norte, Mendocino19 hr
Mar 29, 2:24 PM PDTFreeze WarningEKAHumboldt, Lake, Mendocino19 hr

Nearby

Freeze Watches in California, 2021Every freeze watch 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.