Alert archive / Wyoming / Tornado Warnings in 2011

Tornado Warning 15, NWS Cheyenne, WY

July 2, 2011Converse County, Niobrara County, Wyoming

NWS Cheyenne, WY issued this tornado warning at Jul 2, 2011, 3:50 PM MDT for Converse County, Niobrara County, Wyoming. It was in force for 40 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
Jul 2, 2011, 3:50 PM MDT (21:50 UTC)
Expired
Jul 2, 2011, 4:30 PM MDT
In force
40 min
Issued by
NWS Cheyenne, WY
Area
Storm-based polygon

Counties Converse County, WY, Niobrara County, WY

The radar

The Cheyenne radar (KCYS), 177 km from the middle of the area, began a volume at 21:53 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

TimeReportWhereRemark
Jul 2, 4:25 PM MDTHAIL 1Lost Springs, WY

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.

IssuedProductOfficeLasted
Jul 2, 2:13 PM MDTTornado WatchSPC8 hr

The nearest sounding before it

Rapid City, SD (KUNR), launched 12:00Z, 9.8 hours before the alert went out and 210 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, Rapid City, SD at 12:00Z on 2011-07-02Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 829 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, Rapid City, SD at 12:00Z on 2011-07-02The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -3 square meters per square second.1939Sfc1 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
829 J/kg
Mixed-layer CIN
-69 J/kg
Mixed-layer LCL
993 m above ground
0-6 km bulk shear
25 kt
0-1 km storm-relative helicity
-3 m²/s²
0-3 km storm-relative helicity
41 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.1

Open this sounding in Storm Lab

The text

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

057 
WFUS55 KCYS 022150
TORCYS
WYC009-027-022230-
/O.NEW.KCYS.TO.W.0015.110702T2150Z-110702T2230Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE CHEYENNE WY
350 PM MDT SAT JUL 2 2011

THE NATIONAL WEATHER SERVICE IN CHEYENNE HAS ISSUED A

* TORNADO WARNING FOR...
  EAST CENTRAL CONVERSE COUNTY IN EAST CENTRAL WYOMING...
  SOUTHWESTERN NIOBRARA COUNTY IN EAST CENTRAL WYOMING...

* UNTIL 430 PM MDT

* AT 349 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO. THIS DANGEROUS
  STORM WAS LOCATED 11 MILES WEST OF KEELINE...OR 21 MILES EAST OF
  DOUGLAS...AND MOVING EAST AT 20 MPH.

* LOCATIONS IMPACTED INCLUDE...
  KEELINE...MANVILLE AND LOST SPRINGS.

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.

&&

LAT...LON 4283 10450 4261 10456 4260 10466 4270 10511
      4287 10507
TIME...MOT...LOC 2150Z 280DEG 16KT 4277 10497

$$

MAZUR
2 follow-up statements
019 
WWUS55 KCYS 022207
SVSCYS

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHEYENNE WY
407 PM MDT SAT JUL 2 2011

WYC009-027-022230-
/O.CON.KCYS.TO.W.0015.000000T0000Z-110702T2230Z/
NIOBRARA WY-CONVERSE WY-
407 PM MDT SAT JUL 2 2011

...A TORNADO WARNING REMAINS IN EFFECT FOR EAST CENTRAL CONVERSE AND 
EXTREME SOUTHWESTERN NIOBRARA COUNTIES UNTIL 430 PM MDT...

AT 402 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO.  THIS DANGEROUS
STORM WAS LOCATED 14 MILES WEST OF KEELINE...OR 20 MILES EAST OF
DOUGLAS...MOVING SOUTHEAST AT 10 MPH.

LOCATIONS IMPACTED INCLUDE...
  MAINLY RURAL AREAS OF SOUTHEASTERN CONVERSE AND SOUTHWESTERN
  NIOBRARA 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.

&&

LAT...LON 4279 10504 4282 10485 4264 10483 4268 10501
      4270 10511 4271 10511
TIME...MOT...LOC 2207Z 337DEG 8KT 4270 10501

$$

MAZUR
358 
WWUS55 KCYS 022223
SVSCYS

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHEYENNE WY
423 PM MDT SAT JUL 2 2011

WYC009-027-022233-
/O.EXP.KCYS.TO.W.0015.000000T0000Z-110702T2230Z/
NIOBRARA WY-CONVERSE WY-
423 PM MDT SAT JUL 2 2011

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

THE STORM WHICH PROMPTED THE WARNING HAS MOVED OUT OF THE WARNED
AREA.  HOWEVER SMALL HAIL AND GUSTY WINDS ARE STILL POSSIBLE WITH
THIS THUNDERSTORM.

IN ADDITION...STRONG THUNDERSTORMS MAY REDEVELOP...AND A TORNADO 
WATCH REMAINS IN EFFECT UNTIL 10 PM MDT.

LAT...LON 4279 10504 4282 10485 4264 10483 4268 10501
      4270 10511 4271 10511
TIME...MOT...LOC 2223Z 337DEG 8KT 4267 10499

$$

MAZUR

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 2, 3:15 PM MDTSevere Thunderstorm WarningCYSGoshen, Laramie, Platte25 min
Jul 2, 4:22 PM MDTTornado WarningCYSConverse, Platte38 min
Jul 2, 4:29 PM MDTSevere Thunderstorm WarningCYSConverse, Niobrara46 min
Jul 2, 4:42 PM MDTSevere Thunderstorm WarningCYSGoshen, Niobrara, Platte48 min
Jul 2, 5:01 PM MDTTornado WarningCYSPlatte31 min
Jul 2, 5:30 PM MDTSevere Thunderstorm WarningCYSConverse, Goshen, Niobrara, Platte45 min
Jul 2, 5:40 PM MDTSevere Thunderstorm WarningCYSNiobrara37 min

Nearby

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