Alert archive / California / Winter Storm Watches in 2021

Winter Storm Watch 9, NWS Eureka, CA

December 23, 20215 counties in California

NWS Eureka, CA issued this winter storm watch at Dec 23, 2021, 2:10 AM PST for 5 counties in California. It took effect at Dec 24, 2021, 10:00 AM PST. It was in force for .

The area

The counties it named.

The facts

Issued
Dec 23, 2021, 2:10 AM PST (10:10 UTC)
In effect from
Dec 24, 2021, 10:00 AM PST
Expired
Dec 23, 2021, 1:17 PM PST
In force
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 10:13 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 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 00:00Z on 2021-12-23Temperature 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 2021-12-23The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 231 square meters per square second.1939587897117136156Sfc1 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
1027 m above ground
0-6 km bulk shear
83 kt
0-1 km storm-relative helicity
231 m²/s²
0-3 km storm-relative helicity
416 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

135 
WWUS46 KEKA 231010
WSWEKA

URGENT - WINTER WEATHER MESSAGE
National Weather Service Eureka CA
210 AM PST Thu Dec 23 2021

...HEAVY MOUNTAIN SNOW DURING THE CHRISTMAS HOLIDAY...

.A series of cold upper level storm systems will aid in lowering
snow levels to as low as 2000 feet by Saturday afternoon, and then
as low as 1000 to 2000 feet Sunday night. Periods of heavy showers
spreading across the cold airmass will favor significant mountain
snowfall beginning Friday afternoon and lasting through Monday
morning. Travel across mountain roadways and highway passes will
subsequently be difficult if not impossible.

CAZ107-231815-
/O.NEW.KEKA.WS.A.0009.211224T1800Z-211227T1800Z/
/O.CON.KEKA.WS.W.0009.000000T0000Z-211223T1800Z/
Northern Trinity-
210 AM PST Thu Dec 23 2021

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL 10 AM PST THIS
MORNING ABOVE 4000 FEET...
...WINTER STORM WATCH IN EFFECT FROM FRIDAY MORNING THROUGH
MONDAY MORNING ABOVE 2000 FEET...

* WHAT...For the Winter Storm Warning above 4000 feet, heavy snow.
  Additional snow accumulations of up to 6 inches. Winds gusting
  as high as 40 mph. For the Winter Storm Watch above 2000 feet,
  heavy snow possible. Total snow accumulations of 7 to 24 inches
  possible.

* WHERE...Northern Trinity County.

* WHEN...For the Winter Storm Warning, until 10 AM PST this 
  morning. For the Winter Storm Watch, from Friday morning 
  through Monday morning.

* IMPACTS...Travel could be very difficult to impossible. The
  hazardous conditions could impact the morning or evening
  commute.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If you must travel, keep an extra flashlight, food, and water in
your vehicle in case of an emergency. 

Monitor the latest forecasts for updates on this situation. 

The latest road conditions for the state of California can be
obtained by calling 1-800-GAS-ROAD.

&&

$$

CAZ102-105-106-108-110-111-114-231815-
/O.NEW.KEKA.WS.A.0009.211224T1800Z-211227T1800Z/
Del Norte Interior-Northern Humboldt Interior-
Southern Humboldt Interior-Southern Trinity-
Northwestern Mendocino Interior-Northeastern Mendocino Interior-
Northern Lake-
210 AM PST Thu Dec 23 2021

...WINTER STORM WATCH IN EFFECT FROM FRIDAY MORNING THROUGH
MONDAY MORNING ABOVE 2000 FEET...

* WHAT...Heavy snow possible above 2000 feet. Total snow
  accumulations of 7 to 24 inches possible.

* WHERE...Portions of northwest California.

* WHEN...From Friday morning through Monday morning.

* IMPACTS...Travel could be very difficult to impossible. The
  hazardous conditions could impact the morning or evening
  commute.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the latest forecasts for updates on this situation. 

&&

$$
2 follow-up statements
251 
WWUS46 KEKA 231430
WSWEKA

URGENT - WINTER WEATHER MESSAGE
National Weather Service Eureka CA
630 AM PST Thu Dec 23 2021

...HEAVY MOUNTAIN SNOW EXPECTED DURING THE CHRISTMAS HOLIDAY...

.A series of cold upper level storm systems will aid in lowering
snow levels to as low as 2000 feet by Saturday afternoon, and
then as low as 1000 to 2000 feet Sunday night. Periods of heavy
showers spreading across the cold airmass will favor significant
mountain snowfall beginning Friday afternoon and lasting through
Monday morning. Travel across mountain roadways and highway
passes will subsequently be difficult if not impossible.

CAZ107-232230-
/O.CAN.KEKA.WS.W.0009.000000T0000Z-211223T1800Z/
/O.CON.KEKA.WS.A.0009.211224T1800Z-211227T1800Z/
Northern Trinity-
630 AM PST Thu Dec 23 2021

...WINTER STORM WATCH REMAINS IN EFFECT FROM FRIDAY MORNING
THROUGH MONDAY MORNING ABOVE 2000 FEET...

* WHAT...Heavy snow possible above 2000 feet. Total snow
  accumulations of 7 to 24 inches possible.

* WHERE...Northern Trinity County.

* WHEN...From Friday morning through Monday morning.

* IMPACTS...Travel could be very difficult to impossible. The 
  hazardous conditions could impact the morning or evening 
  commute.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the latest forecasts for updates on this situation. 

&&

$$

CAZ102-105-106-108-110-111-114-232230-
/O.CON.KEKA.WS.A.0009.211224T1800Z-211227T1800Z/
Del Norte Interior-Northern Humboldt Interior-
Southern Humboldt Interior-Southern Trinity-
Northwestern Mendocino Interior-Northeastern Mendocino Interior-
Northern Lake-
630 AM PST Thu Dec 23 2021

...WINTER STORM WATCH REMAINS IN EFFECT FROM FRIDAY MORNING
THROUGH MONDAY MORNING ABOVE 2000 FEET...

* WHAT...Heavy snow possible above 2000 feet. Total snow
  accumulations of 7 to 24 inches possible.

* WHERE...Portions of northwest California.

* WHEN...From Friday morning through Monday morning.

* IMPACTS...Travel could be very difficult to impossible. The 
  hazardous conditions could impact the morning or evening 
  commute.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the latest forecasts for updates on this situation. 

&&

$$
423 
WWUS46 KEKA 232117
WSWEKA

URGENT - WINTER WEATHER MESSAGE
National Weather Service Eureka CA
117 PM PST Thu Dec 23 2021

...HEAVY MOUNTAIN SNOW EXPECTED DURING THE CHRISTMAS HOLIDAY...

.A series of cold upper level storm systems will aid in lowering
snow levels to as low as 2000 feet by Saturday afternoon, and
then as low as 1000 to 2000 feet Sunday night. Periods of heavy
showers spreading across the cold airmass will favor significant
mountain snowfall beginning Friday afternoon and lasting through
Monday morning. Travel across mountain roadways and highway
passes will subsequently be difficult if not impossible.

CAZ102-105>108-110-111-114-240530-
/O.UPG.KEKA.WS.A.0009.211224T1800Z-211227T1800Z/
/O.NEW.KEKA.WS.W.0010.211224T1800Z-211227T1800Z/
Del Norte Interior-Northern Humboldt Interior-
Southern Humboldt Interior-Northern Trinity-Southern Trinity-
Northwestern Mendocino Interior-Northeastern Mendocino Interior-
Northern Lake-
117 PM PST Thu Dec 23 2021

...WINTER STORM WARNING IN EFFECT FROM 10 AM FRIDAY TO 10 AM PST
MONDAY ABOVE 2000 FEET...

* WHAT...Heavy snow expected above 2000 feet. Total snow 
  accumulations of 1 to 54 inches.

* WHERE...Portions of northwest California.

* WHEN...From 10 AM Friday to 10 AM PST Monday.

* IMPACTS...Travel could be very difficult to impossible. The
  hazardous conditions could impact the morning or evening
  commute.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If you must travel, keep an extra flashlight, food, and water in
your vehicle in case of an emergency. 

The latest road conditions for the state of California can be
obtained by calling 1-800-GAS-ROAD.

&&

$$

The office that day

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

IssuedProductOfficeCountiesLasted
Dec 23, 3:11 AM PSTSmall Craft AdvisoryEKA98 min
Dec 23, 1:17 PM PSTWinter Storm WarningEKADel Norte, Humboldt, Lake, Mendocino, Trinity4 days
Dec 23, 3:03 PM PSTSmall Craft AdvisoryEKA5 days

Nearby

Winter Storm Watches in California, 2021Every winter storm 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.