Alert archive / California / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 13, NWS Eureka, CA

September 6, 2017Humboldt County, Trinity County, California

NWS Eureka, CA issued this severe thunderstorm warning at Sep 6, 2017, 4:51 PM PDT for Humboldt County, Trinity County, California. It was in force for 9 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, 4:51 PM PDT (23:51 UTC)
Expired
Sep 6, 2017, 5:00 PM PDT
In force
9 min
Issued by
NWS Eureka, CA
Area
Storm-based polygon
Hail
1.0 in
Wind
50.0 mph

Counties Humboldt County, CA, Trinity County, CA

The radar

The Eureka (Bunker Hill) radar (KBHX), 69 km from the middle of the area, began a volume at 23:51 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, 11.9 hours before the alert went out and 194 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 12:00Z on 2017-09-06Temperature 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 12:00Z on 2017-09-06The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 24 square meters per square second.193958Sfc1 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
1836 m above ground
0-6 km bulk shear
32 kt
0-1 km storm-relative helicity
24 m²/s²
0-3 km storm-relative helicity
119 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

591 
WUUS56 KEKA 062351
SVREKA
CAC023-105-070000-
/O.NEW.KEKA.SV.W.0013.170906T2351Z-170907T0000Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Eureka CA
451 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...
  East central Humboldt County in northwestern California...

* Until 500 PM PDT

* At 450 PM PDT, a severe thunderstorm was located 7 miles northwest
  of Hyampom, or 17 miles south of Willow Creek, moving north at 25
  mph.

  HAZARD...Quarter size hail. 

  SOURCE...Radar indicated. 

  IMPACT...Damage to vehicles is expected. 

* Locations impacted include...
  South of Willow Creek.

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 4064 12343 4061 12354 4081 12370 4086 12350
TIME...MOT...LOC 2350Z 163DEG 22KT 4071 12352 

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

RL/KR

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 5, 8:35 PM PDTSpecial Weather StatementEKAHumboldt25 min
Sep 5, 9:43 PM PDTFire Weather WatchEKA15 hr
Sep 6, 4:44 AM PDTRed Flag WarningEKA29 hr
Sep 6, 4:35 PM PDTSpecial Weather StatementEKATrinity10 min
Sep 6, 4:56 PM PDTSpecial Weather StatementEKADel Norte19 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.