Alert archive / California / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 2, NWS Eureka, CA

August 6, 2017Trinity County, California

NWS Eureka, CA issued this severe thunderstorm warning at Aug 6, 2017, 5:32 PM PDT for Trinity County, California. It was in force for 28 min. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Aug 6, 2017, 5:32 PM PDT (00:32 UTC)
Expired: Aug 6, 2017, 6:00 PM PDT
In force: 28 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 Medford radar (KMAX), 119 km from the middle of the area, began a volume at 00:31 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.

What was reported inside it

Time	Report	Where	Remark
Aug 6, 5:55 PM PDT	HAIL 0.25	1 S Trinity Center, CA	PEA SIZED HAIL REPORTED BY CAMPGROUND PERSONNEL. TIME ESTIMATED FROM RADAR.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Medford/Jackson, OR (KMFR), launched 00:00Z, 0.5 hours before the alert went out and 151 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: 7 J/kg
Mixed-layer CIN: -207 J/kg
Mixed-layer LCL: 3615 m above ground
0-6 km bulk shear: 7 kt
0-1 km storm-relative helicity: 16 m²/s²
0-3 km storm-relative helicity: 39 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

330 
WUUS56 KEKA 070032
SVREKA
CAC105-070100-
/O.NEW.KEKA.SV.W.0002.170807T0032Z-170807T0100Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Eureka CA
532 PM PDT SUN AUG 6 2017

The National Weather Service in Eureka California has issued a

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

* Until 600 PM PDT

* At 530 PM PDT, a severe thunderstorm was located over Carrville, 
  or 25 miles northeast of Weaverville and is nearly stationary. 
  This storm is over the north end of Trinity Lake.

  HAZARD...Quarter size hail. 

  SOURCE...Radar indicated. 

  IMPACT...Damage to vehicles is expected. 

* Locations impacted include...
  Carrville and Trinity Center. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Prepare immediately for large hail and deadly cloud to ground
lightning. Seek shelter inside a well-built structure. Stay away from
windows.

If on or near the north end of Trinity Lake, get away from the water 
and move indoors or inside a vehicle. Remember, lightning can strike 
out to 15 miles from the parent thunderstorm. If you can hear 
thunder, you are close enough to be struck by lightning. Move to 
safe shelter now!  Do not be caught on the water in a thunderstorm.

&&

LAT...LON 4098 12259 4097 12260 4095 12261 4084 12278
      4101 12290 4103 12290 4104 12291 4107 12292
      4107 12294 4108 12295 4115 12265 4100 12255
TIME...MOT...LOC 0030Z 061DEG 7KT 4104 12268 

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

MKK

2 follow-up statements

418 
WWUS56 KEKA 070040
SVSEKA

Severe Weather Statement
National Weather Service Eureka CA
540 PM PDT SUN AUG 6 2017

CAC105-070100-
/O.CON.KEKA.SV.W.0002.000000T0000Z-170807T0100Z/
Trinity CA-
540 PM PDT SUN AUG 6 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 600 PM PDT
FOR NORTHEASTERN TRINITY COUNTY...

At 539 PM PDT, a severe thunderstorm was located over Carrville, or 
24 miles northeast of Weaverville. This storm is over the north end 
of Trinity Lake and is nearly stationary.

HAZARD...Quarter size hail. 

SOURCE...Radar indicated. 

IMPACT...Damage to vehicles is expected. 

Locations impacted include...
Carrville and Trinity Center. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Prepare immediately for large hail and deadly cloud to ground
lightning. Seek shelter inside a well-built structure. Stay away from
windows.

If on or near the north end of Trinity, get away from the water and 
move indoors or inside a vehicle. remember, lightning can strike out 
to 15 miles from the parent thunderstorm. If you can hear thunder, 
you are close enough to be struck by lightning. Move to safe shelter 
now!  Do not be caught on the water in a thunderstorm.

&&

LAT...LON 4098 12259 4097 12260 4095 12261 4094 12269
      4104 12281 4109 12278 4115 12265 4100 12255
TIME...MOT...LOC 0039Z 061DEG 7KT 4103 12270 

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

MKK

977 
WWUS56 KEKA 070055
SVSEKA

Severe Weather Statement
National Weather Service Eureka CA
555 PM PDT SUN AUG 6 2017

CAC105-070104-
/O.EXP.KEKA.SV.W.0002.000000T0000Z-170807T0100Z/
Trinity CA-
555 PM PDT SUN AUG 6 2017

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN TRINITY COUNTY
WILL EXPIRE AT 600 PM PDT...
    
The severe thunderstorm which prompted the warning has weakened.
Therefore, the warning will be allowed to expire.  However small 
hail is still possible with this thunderstorm.

LAT...LON 4098 12259 4097 12260 4095 12261 4094 12269
      4104 12281 4109 12278 4115 12265 4100 12255
TIME...MOT...LOC 0054Z 061DEG 7KT 4103 12270 

$$

MKK

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 6, 5:28 PM PDT	Special Weather Statement	EKA		32 min
Aug 6, 6:08 PM PDT	Special Weather Statement	EKA		22 min
Aug 6, 11:36 PM PDT	Red Flag Warning	EKA		20 hr
Aug 7, 3:43 PM PDT	Special Weather Statement	EKA	Trinity	32 min
Aug 7, 3:50 PM PDT	Special Weather Statement	EKA	Trinity	25 min
Aug 7, 3:57 PM PDT	Special Weather Statement	EKA		33 min
Aug 7, 3:59 PM PDT	Special Weather Statement	EKA	Trinity	16 min
Aug 7, 4:07 PM PDT	Special Weather Statement	EKA	Trinity	8 min
Aug 7, 4:28 PM PDT	Special Weather Statement	EKA		32 min
Aug 7, 4:40 PM PDT	Special Weather Statement	EKA	Trinity	35 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.