Alert archive / Wyoming / Severe Thunderstorm Warnings in 2011

Severe Thunderstorm Warning 2, NWS Cheyenne, WY

May 9, 20114 counties in Wyoming

NWS Cheyenne, WY issued this severe thunderstorm warning at May 9, 2011, 4:57 PM MDT for 4 counties in Wyoming. It was in force for 48 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: May 9, 2011, 4:57 PM MDT (22:57 UTC)
Expired: May 9, 2011, 5:45 PM MDT
In force: 48 min
Issued by: NWS Cheyenne, WY
Area: Storm-based polygon
Hail: 1.5 in
Wind: 60.0 mph

Counties Converse County, WY, Goshen County, WY, Niobrara County, WY, Platte County, WY

The radar

The Cheyenne radar (KCYS), 162 km from the middle of the area, began a volume at 23:01 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
May 9, 5:03 PM MDT	HAIL 0.25	Hartville, 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.

Issued	Product	Office	Lasted
May 9, 2:26 PM MDT	Severe Thunderstorm Watch	SPC	7 hr

The nearest sounding before it

Rapid City, SD (KUNR), launched 12:00Z, 11.0 hours before the alert went out and 226 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: 90 J/kg
Mixed-layer CIN: -588 J/kg
Mixed-layer LCL: 782 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 95 m²/s²
0-3 km storm-relative helicity: 108 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.

225 
WUUS55 KCYS 092257
SVRCYS
WYC009-015-027-031-092345-
/O.NEW.KCYS.SV.W.0002.110509T2257Z-110509T2345Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE CHEYENNE WY
457 PM MDT MON MAY 9 2011

THE NATIONAL WEATHER SERVICE IN CHEYENNE HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  EAST CENTRAL CONVERSE COUNTY IN EAST CENTRAL WYOMING...
  NORTHWESTERN GOSHEN COUNTY IN SOUTHEAST WYOMING...
  SOUTHWESTERN NIOBRARA COUNTY IN EAST CENTRAL WYOMING...
  NORTHEASTERN PLATTE COUNTY IN SOUTHEAST WYOMING...

* UNTIL 545 PM MDT

* AT 451 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING PING PONG BALL
  SIZE HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH.  THESE STORMS
  WERE LOCATED ALONG A LINE EXTENDING FROM 10 MILES NORTHEAST OF
  GLENDO TO 9 MILES NORTH OF GUERNSEY TO 5 MILES NORTHWEST OF     
  GRAYROCKS RESERVOIR...AND MOVING TO THE NORTHEAST AT 25 MPH.

* LOCATIONS IMPACTED INCLUDE...
  GUERNSEY...KEELINE...FORT LARAMIE NATIONAL HISTORIC SITE...FORT
  LARAMIE AND HARTVILLE.

THIS WARNING REPLACES THE PREVIOUSLY ISSUED WARNING FOR NORTHERN GOSHEN
COUNTY.  

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT FOR THE AREA UNTIL 9 
PM.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

SEVERE THUNDERSTORMS PRODUCE DAMAGING WIND IN EXCESS OF 60 MILES PER
HOUR...DESTRUCTIVE HAIL...DEADLY LIGHTNING...AND VERY HEAVY RAIN. FOR
YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF YOUR
HOME OR BUSINESS. HEAVY RAINS FLOOD ROADS QUICKLY SO DO NOT DRIVE
INTO AREAS WHERE WATER COVERS THE ROAD.

THESE STORMS HAVE A HISTORY OF PRODUCING LARGE HAIL. SEEK SHELTER NOW
INSIDE A STURDY STRUCTURE AND STAY AWAY FROM WINDOWS.

&&

LAT...LON 4304 10487 4221 10432 4215 10495 4259 10508
TIME...MOT...LOC 2256Z 270DEG 16KT 4264 10492 4239 10476
          4218 10479
WIND...HAIL 60MPH 1.50IN

$$

MSW

3 follow-up statements

890 
WWUS55 KCYS 092315
SVSCYS

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHEYENNE WY
515 PM MDT MON MAY 9 2011

WYC009-015-027-031-092345-
/O.CON.KCYS.SV.W.0002.000000T0000Z-110509T2345Z/
NIOBRARA WY-GOSHEN WY-PLATTE WY-CONVERSE WY-
515 PM MDT MON MAY 9 2011

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT FOR EXTREME EAST
CENTRAL CONVERSE...NORTHEASTERN PLATTE...NORTHWESTERN GOSHEN AND
SOUTHWESTERN NIOBRARA COUNTIES UNTIL 545 PM MDT...

AT 513 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING PING PONG BALL SIZE
HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH.  THESE STORMS WERE
LOCATED ALONG A LINE EXTENDING FROM 8 MILES SOUTHWEST OF KEELINE TO 
10 MILES NORTHEAST OF GUERNSEY TO GRAYROCKS RESERVOIR...MOVING TO
THE NORTHEAST AT 25 MPH.

LOCATIONS IMPACTED INCLUDE...
  KEELINE.

A SEVERE THUNDERSTORM WATCH IS IN EFFECT UNTIL 9 PM. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

SEVERE THUNDERSTORMS PRODUCE DAMAGING WIND IN EXCESS OF 60 MILES PER
HOUR...DESTRUCTIVE HAIL...DEADLY LIGHTNING...AND VERY HEAVY RAIN. FOR
YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF YOUR
HOME OR BUSINESS. HEAVY RAINS FLOOD ROADS QUICKLY SO DO NOT DRIVE
INTO AREAS WHERE WATER COVERS THE ROAD.

IF YOU ARE IN THE PATH OF THIS STORM...PREPARE IMMEDIATELY FOR LARGE
HAIL AND DEADLY CLOUD TO GROUND LIGHTNING. PEOPLE OUTSIDE SHOULD MOVE
TO A SHELTER...PREFERABLY INSIDE A STRONG BUILDING AND AWAY FROM
WINDOWS.

&&

LAT...LON 4224 10487 4265 10498 4300 10489 4290 10478
      4234 10441
TIME...MOT...LOC 2315Z 270DEG 16KT 4264 10480 4239 10465
          4218 10468
WIND...HAIL 60MPH 1.50IN

$$

MSW

249 
WWUS55 KCYS 092336
SVSCYS

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHEYENNE WY
536 PM MDT MON MAY 9 2011

WYC009-015-027-031-092345-
/O.CON.KCYS.SV.W.0002.000000T0000Z-110509T2345Z/
NIOBRARA WY-GOSHEN WY-PLATTE WY-CONVERSE WY-
536 PM MDT MON MAY 9 2011

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT FOR EXTREME EAST
CENTRAL CONVERSE...NORTHEASTERN PLATTE...NORTHWESTERN GOSHEN AND
SOUTHWESTERN NIOBRARA COUNTIES UNTIL 545 PM MDT...

AT 530 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING PING PONG BALL SIZE
HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH.  THESE STORMS WERE
LOCATED ALONG A LINE EXTENDING FROM 9 MILES NORTHWEST OF KEELINE TO 5
MILES SOUTH OF MANVILLE TO 7 MILES SOUTH OF RAWHIDE BUTTES TO 9 MILES
SOUTHWEST OF JAY EM...MOVING TO THE NORTHEAST AT 20 MPH.

LOCATIONS IMPACTED INCLUDE...
  MAINLY RURAL AREAS OF SOUTHWESTERN NIOBRARA COUNTY.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 9 PM. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

SEVERE THUNDERSTORMS PRODUCE DAMAGING WIND IN EXCESS OF 60 MILES PER
HOUR...DESTRUCTIVE HAIL...DEADLY LIGHTNING...AND VERY HEAVY RAIN. FOR
YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF YOUR
HOME OR BUSINESS. HEAVY RAINS FLOOD ROADS QUICKLY SO DO NOT DRIVE
INTO AREAS WHERE WATER COVERS THE ROAD.

PREPARE IMMEDIATELY FOR LARGE HAIL AND DAMAGING WINDS IF YOU ARE IN
THE PATH OF THIS STORM. PEOPLE OUTSIDE SHOULD MOVE TO A SHELTER...
PREFERABLY INSIDE A STRONG BUILDING AND AWAY FROM WINDOWS.

&&

LAT...LON 4233 10450 4277 10494 4278 10495 4300 10489
      4290 10478 4238 10443
TIME...MOT...LOC 2334Z 270DEG 16KT 4285 10483 4271 10460
          4248 10447 4236 10444
WIND...HAIL 60MPH 1.50IN

$$

MSW

615 
WWUS55 KCYS 092344
SVSCYS

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHEYENNE WY
544 PM MDT MON MAY 9 2011

WYC009-015-027-031-092354-
/O.EXP.KCYS.SV.W.0002.000000T0000Z-110509T2345Z/
NIOBRARA WY-GOSHEN WY-PLATTE WY-CONVERSE WY-
544 PM MDT MON MAY 9 2011

...THE SEVERE THUNDERSTORM WARNING FOR EXTREME EAST CENTRAL
CONVERSE...NORTHEASTERN PLATTE...NORTHWESTERN GOSHEN AND SOUTHWESTERN
NIOBRARA COUNTIES WILL EXPIRE AT 545 PM MDT...

THE LINE OF STORMS WHICH PROMPTED THE WARNING HAS MOVED OUT OF THE 
WARNED AREA.  A NEW WARNING HAS BEEN ISSUED FOR NORTHWEST GOSHEN
COUNTY AND SOUTHERN NIOBRARA COUNTY UNTIL 630 PM.  

ADDITIONAL STRONG THUNDERSTORMS ARE STILL POSSIBLE...AND A SEVERE 
THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 9 PM. 

LAT...LON 4233 10450 4277 10494 4278 10495 4300 10489
      4290 10478 4238 10443
TIME...MOT...LOC 2344Z 270DEG 16KT 4285 10477 4271 10454
          4248 10441 4236 10438

$$

MSW

The office that day

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

Issued	Product	Office	Counties	Lasted
May 9, 4:23 PM MDT	Severe Thunderstorm Warning	CYS	Platte	37 min
May 9, 4:59 PM MDT	Severe Thunderstorm Warning	CYS	Converse, Goshen, Niobrara, Platte	46 min
May 9, 5:43 PM MDT	Severe Thunderstorm Warning	CYS	Goshen, Niobrara	43 min

Nearby

Severe Thunderstorm Warnings in Wyoming, 2011 Every severe thunderstorm warning 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.