Alert archive / California / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 14, NWS Eureka, CA

September 6, 2017Trinity County, California

NWS Eureka, CA issued this severe thunderstorm warning at Sep 6, 2017, 5:40 PM PDT for Trinity County, California. It was in force for 20 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
Sep 6, 2017, 5:40 PM PDT (00:40 UTC)
Expired
Sep 6, 2017, 6:00 PM PDT
In force
20 min
Issued by
NWS Eureka, CA
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

County Trinity County, CA

The radar

The Eureka (Bunker Hill) radar (KBHX), 84 km from the middle of the area, began a volume at 00:41 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, 0.7 hours before the alert went out and 222 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 2017-09-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 146 joules per kilogram.LCLLFCEL10008507005003002001001 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 2017-09-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -6 square meters per square second.19395878Sfc1 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
146 J/kg
Mixed-layer CIN
-317 J/kg
Mixed-layer LCL
1964 m above ground
0-6 km bulk shear
28 kt
0-1 km storm-relative helicity
-6 m²/s²
0-3 km storm-relative helicity
62 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.2

Open this sounding in Storm Lab

The text

As transmitted.

900 
WUUS56 KEKA 070040
SVREKA
CAC105-070115-
/O.NEW.KEKA.SV.W.0014.170907T0040Z-170907T0115Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Eureka CA
540 PM PDT WED SEP 6 2017

The National Weather Service in Eureka California has issued a

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

* Until 615 PM PDT

* At 539 PM PDT, a severe thunderstorm was located over Forest Glen,
  or 14 miles southwest of Hayfork, moving north at 20 mph.

  HAZARD...Up to 60 mph wind gusts and quarter size hail. 

  SOURCE...Radar indicated. 

  IMPACT...Hail damage to vehicles is expected. Expect wind damage 
           to roofs, siding, and trees. 

* Locations impacted include...
  Forest Glen.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Large hail and damaging winds and continuous cloud to ground
lightning is occurring with this storm. Move indoors immediately.
Lightning is one of nature's leading killers. Remember, if you can
hear thunder, you are close enough to be struck by lightning.

&&

LAT...LON 4035 12323 4033 12331 4046 12348 4055 12328
TIME...MOT...LOC 0039Z 159DEG 19KT 4040 12330 

HAIL...1.00IN
WIND...60MPH
 
$$

KR
2 follow-up statements
303 
WWUS56 KEKA 070052
SVSEKA

Severe Weather Statement
National Weather Service Eureka CA
552 PM PDT WED SEP 6 2017

CAC105-070115-
/O.CON.KEKA.SV.W.0014.000000T0000Z-170907T0115Z/
Trinity CA-
552 PM PDT WED SEP 6 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 615 PM PDT
FOR WEST CENTRAL TRINITY COUNTY...

At 551 PM PDT, a severe thunderstorm was located near Forest Glen, or
12 miles southwest of Hayfork, moving north at 20 mph.

HAZARD...Up to 60 mph wind gusts and up to penny size hail. 

SOURCE...Radar indicated. 

IMPACT...Expect damage to roofs, siding, and trees. 

This severe thunderstorm will remain over mainly rural areas of west
central Trinity County.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Continuous cloud to ground lightning is occurring with this storm.
Move indoors immediately. Lightning is one of nature's leading
killers. Remember, if you can hear thunder, you are close enough to
be struck by lightning.

&&

LAT...LON 4043 12329 4040 12336 4048 12344 4053 12332
TIME...MOT...LOC 0051Z 159DEG 19KT 4046 12333 

HAIL...0.75IN
WIND...60MPH
 
$$

KR
080 
WWUS56 KEKA 070100
SVSEKA

Severe Weather Statement
National Weather Service Eureka CA
600 PM PDT WED SEP 6 2017

CAC105-070109-
/O.CAN.KEKA.SV.W.0014.000000T0000Z-170907T0115Z/
Trinity CA-
600 PM PDT WED SEP 6 2017

...THE SEVERE THUNDERSTORM WARNING FOR WEST CENTRAL TRINITY COUNTY IS
CANCELLED...
                
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 has been cancelled.

LAT...LON 4043 12329 4040 12336 4048 12344 4053 12332
TIME...MOT...LOC 0057Z 159DEG 19KT 4050 12335 

$$

KR

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 6, 5:58 PM PDTSevere Thunderstorm WarningEKATrinity12 min
Sep 6, 6:13 PM PDTSpecial Weather StatementEKATrinity17 min
Sep 7, 3:15 AM PDTSmall Craft AdvisoryEKA10 days
Sep 7, 4:24 AM PDTSpecial Weather StatementEKA51 min
Sep 7, 4:27 AM PDTSpecial Weather StatementEKATrinity33 min
Sep 7, 5:34 AM PDTSpecial Weather StatementEKADel Norte26 min
Sep 7, 5:59 AM PDTSpecial Weather StatementEKADel Norte46 min
Sep 7, 6:49 AM PDTSpecial Weather StatementEKADel Norte26 min
Sep 7, 7:22 AM PDTSpecial Weather StatementEKADel Norte23 min

Nearby

Severe Thunderstorm Warnings in California, 2017Every 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.