Alert archive / Nebraska / Tornado Warnings in 2011

Tornado Warning 26, NWS Cheyenne, WY

July 11, 2011Sioux County, Nebraska; Niobrara County, Wyoming

NWS Cheyenne, WY issued this tornado warning at Jul 11, 2011, 3:44 PM MDT for Sioux County, Nebraska; Niobrara County, Wyoming. It was in force for 46 min. 2 reports 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: Jul 11, 2011, 3:44 PM MDT (21:44 UTC)
Expired: Jul 11, 2011, 4:30 PM MDT
In force: 46 min
Issued by: NWS Cheyenne, WY
Area: Storm-based polygon

Counties Sioux County, NE, Niobrara County, WY

The radar

The Rapid City radar (KUDX), 161 km from the middle of the area, began a volume at 21:44 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
Jul 11, 4:00 PM MDT	HAIL 1	10 S Redbird, WY	OBSERVER REPORTED THAT IN A ONE MILE SWATH NEAR THE JUNCTION OF HWY 85 AND 270, TREES WERE STRIPPED OF BARK AND LEAVES. GROUND IS COVERED WITH HAIL. WATER COVERS PORTIONS OF HWY 85 10 MI SOUTH OF REDBIRD.
Jul 11, 4:00 PM MDT	HAIL 1.75	11 Ssw Redbird, WY	VERY HEAVY RAIN WITH WINDS OF 50 TO 60 MPH.

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

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Jul 11, 2:07 PM MDT	Severe Thunderstorm Watch	SPC	7 hr

The nearest sounding before it

Rapid City, SD (KUNR), launched 12:00Z, 9.7 hours before the alert went out and 154 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1860 m above ground
0-6 km bulk shear: 23 kt
0-1 km storm-relative helicity: -49 m²/s²
0-3 km storm-relative helicity: 74 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

965 
WFUS55 KCYS 112144
TORCYS
NEC165-WYC027-112230-
/O.NEW.KCYS.TO.W.0026.110711T2144Z-110711T2230Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE CHEYENNE WY
344 PM MDT MON JUL 11 2011

THE NATIONAL WEATHER SERVICE IN CHEYENNE HAS ISSUED A

* TORNADO WARNING FOR...
  NORTHWESTERN SIOUX COUNTY IN THE PANHANDLE OF NEBRASKA...
  CENTRAL NIOBRARA COUNTY IN EAST CENTRAL WYOMING...

* UNTIL 430 PM MDT

* AT 341 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO. THIS DANGEROUS
  STORM WAS LOCATED 12 MILES SOUTHWEST OF REDBIRD...OR 24 MILES NORTH
  OF LUSK...AND MOVING SOUTHEAST AT 25 MPH.

* LOCATIONS IMPACTED INCLUDE...
  MAINLY RURAL AREAS OF EASTERN NIOBRARA AND NORTHWESTERN SIOUX
  COUNTIES.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS TORNADO WARNING REPLACES THE SEVERE THUNDERSTORM WARNING THAT
WAS IN EFFECT FOR THE SAME AREA.

TAKE COVER NOW. MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF A
STURDY BUILDING. AVOID WINDOWS. IF IN A MOBILE HOME...A VEHICLE OR
OUTDOORS...MOVE TO THE CLOSEST SUBSTANTIAL SHELTER AND PROTECT
YOURSELF FROM FLYING DEBRIS.

TO REPORT SEVERE WEATHER...CONTACT YOUR NEAREST LAW ENFORCEMENT
AGENCY. THEY WILL RELAY YOUR REPORT TO THE NATIONAL WEATHER SERVICE
IN CHEYENNE.

&&

LAT...LON 4314 10404 4301 10404 4301 10394 4299 10393
      4267 10438 4313 10458 4325 10438
TIME...MOT...LOC 2144Z 323DEG 37KT 4308 10439

$$

CLAYCOMB

2 follow-up statements

983 
WWUS55 KCYS 112206
SVSCYS

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHEYENNE WY
406 PM MDT MON JUL 11 2011

NEC165-WYC027-112230-
/O.CON.KCYS.TO.W.0026.000000T0000Z-110711T2230Z/
NIOBRARA WY-SIOUX NE-
406 PM MDT MON JUL 11 2011

...A TORNADO WARNING REMAINS IN EFFECT FOR NORTHWESTERN SIOUX AND
EAST CENTRAL NIOBRARA COUNTIES UNTIL 430 PM MDT...

AT 404 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO.  THIS DANGEROUS
STORM WAS LOCATED 15 MILES SOUTH OF REDBIRD...OR 20 MILES NORTHEAST
OF LUSK...MOVING SOUTHEAST AT 30 MPH.

LOCATIONS IMPACTED INCLUDE...
  MAINLY RURAL AREAS OF EASTERN NIOBRARA AND NORTHWESTERN SIOUX
  COUNTIES.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW. MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF A
STURDY BUILDING. AVOID WINDOWS. IF IN A MOBILE HOME...A VEHICLE OR
OUTDOORS...MOVE TO THE CLOSEST SUBSTANTIAL SHELTER AND PROTECT
YOURSELF FROM FLYING DEBRIS.

TO REPORT SEVERE WEATHER...CONTACT YOUR NEAREST LAW ENFORCEMENT
AGENCY. THEY WILL RELAY YOUR REPORT TO THE NATIONAL WEATHER SERVICE
IN CHEYENNE.

&&

LAT...LON 4300 10452 4322 10429 4314 10404 4301 10404
      4301 10394 4299 10393 4267 10438
TIME...MOT...LOC 2206Z 322DEG 36KT 4301 10428

$$

CLAYCOMB

706 
WWUS55 KCYS 112225
SVSCYS

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHEYENNE WY
425 PM MDT MON JUL 11 2011

NEC165-WYC027-112235-
/O.EXP.KCYS.TO.W.0026.000000T0000Z-110711T2230Z/
NIOBRARA WY-SIOUX NE-
425 PM MDT MON JUL 11 2011

...THE TORNADO WARNING FOR NORTHWESTERN SIOUX AND EAST CENTRAL
NIOBRARA COUNTIES WILL EXPIRE AT 430 PM MDT...

THE TORNADO THREAT HAS DIMINISHED...THEREFORE THE TORNADO WARNING HAS
EXPIRED. HOWEVER...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT
FOR THE AREA.

TO REPORT SEVERE WEATHER...CONTACT YOUR NEAREST LAW ENFORCEMENT
AGENCY. THEY WILL RELAY YOUR REPORT TO THE NATIONAL WEATHER SERVICE
IN CHEYENNE.

LAT...LON 4300 10452 4322 10429 4314 10404 4301 10404
      4301 10394 4299 10393 4267 10438
TIME...MOT...LOC 2225Z 322DEG 36KT 4286 10412

$$

CLAYCOMB

The office that day

Everything else NWS Cheyenne, WY issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 11, 2:05 PM MDT	Severe Thunderstorm Warning	CYS	Banner, Scotts Bluff	40 min
Jul 11, 3:31 PM MDT	Severe Thunderstorm Warning	CYS	Dawes	59 min
Jul 11, 4:24 PM MDT	Severe Thunderstorm Warning	CYS	Sioux	51 min
Jul 11, 5:08 PM MDT	Severe Thunderstorm Warning	CYS	Dawes, Sioux	26 min
Jul 11, 5:59 PM MDT	Severe Thunderstorm Warning	CYS	Cheyenne, Morrill	39 min
Jul 11, 2:38 PM MDT	Severe Thunderstorm Warning	CYS	Niobrara	41 min
Jul 11, 3:16 PM MDT	Severe Thunderstorm Warning	CYS	Niobrara	29 min

Nearby

Tornado Warnings in Nebraska, 2011 Tornado Warnings in Wyoming, 2011 Every tornado warning in 2011 Tornadoes in 2011

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.