Alert archive / California / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 9, NWS Eureka, CA

August 10, 2017Trinity County, California

NWS Eureka, CA issued this severe thunderstorm warning at Aug 10, 2017, 3:30 PM PDT for Trinity County, California. It was in force for 30 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Aug 10, 2017, 3:30 PM PDT (22:30 UTC)
Expired: Aug 10, 2017, 4:00 PM PDT
In force: 30 min
Issued by: NWS Eureka, CA
Area: Storm-based polygon
Hail: 1.0 in
Wind: 50.0 mph

County Trinity County, CA

The radar

The Eureka (Bunker Hill) radar (KBHX), 88 km from the middle of the area, began a volume at 22:32 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, 10.5 hours before the alert went out and 170 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 130 J/kg
Mixed-layer CIN: -439 J/kg
Mixed-layer LCL: 1837 m above ground
0-6 km bulk shear: 13 kt
0-1 km storm-relative helicity: -5 m²/s²
0-3 km storm-relative helicity: 32 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

058 
WUUS56 KEKA 102230
SVREKA
CAC105-102300-
/O.NEW.KEKA.SV.W.0009.170810T2230Z-170810T2300Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Eureka CA
330 PM PDT THU AUG 10 2017

The National Weather Service in Eureka California has issued a

* Severe Thunderstorm Warning for...
  West central Trinity County in northwestern California...

* Until 400 PM PDT

* At 330 PM PDT, a severe thunderstorm was located over Denny, or 12
  miles east of Willow Creek, and is nearly stationary.

  HAZARD...Quarter size hail. 

  SOURCE...Radar indicated. 

  IMPACT...Damage to vehicles is possible. 

* Locations impacted include...
  Denny.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4088 12347 4097 12343 4097 12329 4085 12332
TIME...MOT...LOC 2230Z 258DEG 1KT 4092 12339 

HAIL...1.00IN
WIND...<50MPH
 
$$

RPA

2 follow-up statements

905 
WWUS56 KEKA 102245
SVSEKA

Severe Weather Statement
National Weather Service Eureka CA
345 PM PDT THU AUG 10 2017

CAC105-102300-
/O.CON.KEKA.SV.W.0009.000000T0000Z-170810T2300Z/
Trinity CA-
345 PM PDT THU AUG 10 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 400 PM PDT
FOR WEST CENTRAL TRINITY COUNTY...

At 345 PM PDT, a severe thunderstorm was located over Denny, or 12
miles east of Willow Creek, and is nearly stationary.

HAZARD...Quarter size hail. 

SOURCE...Radar indicated. 

IMPACT...Damage to vehicles is expected. 

Locations impacted include...
Denny.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4088 12347 4097 12343 4097 12329 4085 12332
TIME...MOT...LOC 2245Z 258DEG 1KT 4092 12338 

HAIL...1.00IN
WIND...<50MPH
 
$$

RPA

397 
WWUS56 KEKA 102259
SVSEKA

Severe Weather Statement
National Weather Service Eureka CA
359 PM PDT THU AUG 10 2017

CAC105-102309-
/O.EXP.KEKA.SV.W.0009.000000T0000Z-170810T2300Z/
Trinity CA-
359 PM PDT THU AUG 10 2017

...THE SEVERE THUNDERSTORM WARNING FOR WEST CENTRAL TRINITY COUNTY
WILL EXPIRE AT 400 PM PDT...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore the warning will be allowed to expire.

LAT...LON 4088 12347 4097 12343 4097 12329 4085 12332
TIME...MOT...LOC 2259Z 258DEG 1KT 4092 12338 

$$

RPA

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 10, 1:17 PM PDT	Special Weather Statement	EKA	Trinity	28 min
Aug 10, 1:57 PM PDT	Special Weather Statement	EKA	Trinity	33 min
Aug 10, 2:09 PM PDT	Special Weather Statement	EKA	Trinity	36 min
Aug 10, 2:26 PM PDT	Small Craft Advisory	EKA		8 days
Aug 10, 2:28 PM PDT	Special Weather Statement	EKA	Trinity	32 min
Aug 10, 2:43 PM PDT	Special Weather Statement	EKA	Trinity	32 min
Aug 10, 3:06 PM PDT	Special Weather Statement	EKA	Trinity	39 min
Aug 10, 3:28 PM PDT	Severe Thunderstorm Warning	EKA	Trinity	32 min
Aug 10, 3:53 PM PDT	Special Weather Statement	EKA	Trinity	37 min
Aug 10, 4:03 PM PDT	Special Weather Statement	EKA	Mendocino	42 min
Aug 10, 4:05 PM PDT	Severe Thunderstorm Warning	EKA	Trinity	25 min
Aug 10, 4:08 PM PDT	Severe Thunderstorm Warning	EKA	Trinity	37 min
Aug 10, 4:30 PM PDT	Severe Thunderstorm Warning	EKA	Trinity	30 min
Aug 10, 4:45 PM PDT	Areal Flood Advisory	EKA	Trinity	105 min
Aug 10, 4:48 PM PDT	Special Weather Statement	EKA	Humboldt	27 min
Aug 10, 4:52 PM PDT	Special Weather Statement	EKA	Trinity	23 min

Nearby

Severe Thunderstorm Warnings in California, 2017 Every severe thunderstorm warning in 2017

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.