Alert archive / California / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 8, NWS Eureka, CA

August 10, 2017Trinity County, California

NWS Eureka, CA issued this severe thunderstorm warning at Aug 10, 2017, 3:28 PM PDT for Trinity County, California. It was in force for 32 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, 3:28 PM PDT (22:28 UTC)
Expired: Aug 10, 2017, 4:00 PM PDT
In force: 32 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), 110 km from the middle of the area, began a volume at 22:27 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 169 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.

864 
WUUS56 KEKA 102228
SVREKA
CAC105-102300-
/O.NEW.KEKA.SV.W.0008.170810T2228Z-170810T2300Z/

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

The National Weather Service in Eureka California has issued a

* Severe Thunderstorm Warning for...
  Central Trinity County in northwestern California...

* Until 400 PM PDT

* At 326 PM PDT, severe thunderstorms were located along a line
  extending from 7 miles north of Junction City to 6 miles northwest
  of Helena, and are nearly stationary.

  HAZARD...Quarter size hail. 

  SOURCE...Radar indicated. 

  IMPACT...Damage to vehicles is possible. 

* Locations impacted include...
  Rural areas of Trinity County north of Weaverville and Helena.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4089 12294 4093 12322 4082 12328 4078 12301
TIME...MOT...LOC 2226Z 258DEG 2KT 4083 12301 4084 12322 

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

RPA

2 follow-up statements

669 
WWUS56 KEKA 102243
SVSEKA

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

CAC105-102300-
/O.CON.KEKA.SV.W.0008.000000T0000Z-170810T2300Z/
Trinity CA-
343 PM PDT THU AUG 10 2017

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

At 342 PM PDT, severe thunderstorms were located along a line
extending from 7 miles north of Junction City to 6 miles northwest of
Helena, and are nearly stationary.
 
HAZARD...Quarter size hail. 

SOURCE...Radar indicated. 

IMPACT...Damage to vehicles is possible. 

Locations impacted include...
Mainly rural areas of northern Trinity County north of Helena to 
Weaverville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4078 12301 4082 12327 4093 12321 4089 12294
TIME...MOT...LOC 2242Z 258DEG 2KT 4083 12300 4084 12321 

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

RPA

820 
WWUS56 KEKA 102300
SVSEKA

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

CAC105-102310-
/O.EXP.KEKA.SV.W.0008.000000T0000Z-170810T2300Z/
Trinity CA-
400 PM PDT THU AUG 10 2017

...THE SEVERE THUNDERSTORM WARNING FOR CENTRAL TRINITY COUNTY HAS
EXPIRED...

The storms which prompted the warning have weakened. Therefore, the 
warning has been allowed to expire.

LAT...LON 4078 12301 4082 12327 4093 12321 4089 12294
TIME...MOT...LOC 2300Z 258DEG 2KT 4083 12299 4084 12320 

$$

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, 3:30 PM PDT	Severe Thunderstorm Warning	EKA	Trinity	30 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.