Alert archive / Wyoming / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 81, NWS Cheyenne, WY

July 7, 2021Goshen County, Niobrara County, Wyoming; Sioux County, Nebraska

NWS Cheyenne, WY issued this severe thunderstorm warning at Jul 7, 2021, 3:58 PM MDT for Goshen County, Niobrara County, Wyoming; Sioux County, Nebraska. It was in force for 47 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 7, 2021, 3:58 PM MDT (21:58 UTC)
Expired: Jul 7, 2021, 4:45 PM MDT
In force: 47 min
Issued by: NWS Cheyenne, WY
Area: Storm-based polygon
Hail: 1.5 in
Wind: 60.0 mph

Counties Sioux County, NE, Goshen County, WY, Niobrara County, WY

The radar

The Cheyenne radar (KCYS), 160 km from the middle of the area, began a volume at 22:01 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
Jul 7, 4:41 PM MDT	HAIL 1	11 Ese Jay Em, WY	DELAYED REPORT. TIME ESTIMATED FROM RADAR.
Jul 7, 4:41 PM MDT	HAIL 1	7 Sse Prairie Center, WY	DELAYED REPORT. TIME ESTIMATED FROM RADAR.

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

The nearest sounding before it

Rapid City, SD (KUNR), launched 12:00Z, 10.0 hours before the alert went out and 204 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: 23 J/kg
Mixed-layer CIN: -353 J/kg
Mixed-layer LCL: 1431 m above ground
0-6 km bulk shear: 41 kt
0-1 km storm-relative helicity: 78 m²/s²
0-3 km storm-relative helicity: 186 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

047 
WUUS55 KCYS 072158
SVRCYS
NEC165-WYC015-027-072245-
/O.NEW.KCYS.SV.W.0081.210707T2158Z-210707T2245Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Cheyenne WY
358 PM MDT Wed Jul 7 2021

The National Weather Service in Cheyenne has issued a

* Severe Thunderstorm Warning for...
  West central Sioux County in the Panhandle of Nebraska...
  South central Niobrara County in east central Wyoming...
  Northern Goshen County in southeastern Wyoming...

* Until 445 PM MDT.

* At 358 PM MDT, a severe thunderstorm was located 7 miles northwest
  of Prairie Center, or 13 miles southeast of Lusk, moving south at
  35 mph.

  HAZARD...Ping pong ball size hail and 60 mph wind gusts.

  SOURCE...Radar indicated.

  IMPACT...People and animals outdoors will be injured. Expect hail 
           damage to roofs, siding, windows, and vehicles. Expect 
           wind damage to roofs, siding, and trees.

* Locations impacted include...
  Prairie Center and Jay Em. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

To report severe weather, contact your nearest law enforcement
agency. They will send your report to the National Weather Service
office in Cheyenne.

&&

LAT...LON 4269 10435 4269 10416 4237 10393 4226 10459
TIME...MOT...LOC 2158Z 009DEG 29KT 4260 10428 

HAIL...1.50IN
WIND...60MPH
 
$$

Claycomb

2 follow-up statements

297 
WWUS55 KCYS 072216
SVSCYS

Severe Weather Statement
National Weather Service Cheyenne WY
416 PM MDT Wed Jul 7 2021

WYC027-072225-
/O.CAN.KCYS.SV.W.0081.000000T0000Z-210707T2245Z/
Niobrara WY-
416 PM MDT Wed Jul 7 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTH CENTRAL NIOBRARA COUNTY
IS CANCELLED...
    
The severe thunderstorm which prompted the warning has moved out of 
the warned area. Therefore, the warning has been cancelled.

LAT...LON 4260 10433 4261 10415 4237 10393 4226 10459
TIME...MOT...LOC 2215Z 340DEG 27KT 4255 10424 

$$

NEC165-WYC015-072245-
/O.CON.KCYS.SV.W.0081.000000T0000Z-210707T2245Z/
Sioux NE-Goshen WY-
416 PM MDT Wed Jul 7 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 445 PM MDT
FOR SOUTHWESTERN SIOUX AND NORTHERN GOSHEN COUNTIES...

At 415 PM MDT, a severe thunderstorm was located near Prairie Center,
or 18 miles southeast of Lusk, moving south at 30 mph.

HAZARD...Golf ball size hail and 60 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...People and animals outdoors will be injured. Expect hail 
         damage to roofs, siding, windows, and vehicles. Expect wind 
         damage to roofs, siding, and trees.

Locations impacted include...
Prairie Center and Jay Em. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

To report severe weather contact your nearest law enforcement agency.
They will send your report to the National Weather Service office in
Cheyenne.

&&

LAT...LON 4260 10433 4261 10415 4237 10393 4226 10459
TIME...MOT...LOC 2215Z 340DEG 27KT 4255 10424 

HAIL...1.75IN
WIND...60MPH
 
$$

Claycomb

212 
WWUS55 KCYS 072229
SVSCYS

Severe Weather Statement
National Weather Service Cheyenne WY
429 PM MDT Wed Jul 7 2021

NEC165-WYC015-072245-
/O.CON.KCYS.SV.W.0081.000000T0000Z-210707T2245Z/
Sioux NE-Goshen WY-
429 PM MDT Wed Jul 7 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 445 PM MDT
FOR SOUTHWESTERN SIOUX AND NORTHEASTERN GOSHEN COUNTIES...

At 428 PM MDT, a severe thunderstorm was located near Prairie Center,
or 23 miles southeast of Lusk, moving south at 30 mph.

HAZARD...Golf ball size hail and 60 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...People and animals outdoors will be injured. Expect hail 
         damage to roofs, siding, windows, and vehicles. Expect wind 
         damage to roofs, siding, and trees.

Locations impacted include...
Prairie Center.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

To report severe weather contact your nearest law enforcement agency.
They will send your report to the National Weather Service office in
Cheyenne.

&&

LAT...LON 4254 10430 4259 10414 4237 10393 4234 10440
TIME...MOT...LOC 2228Z 004DEG 25KT 4247 10423 

HAIL...1.75IN
WIND...60MPH
 
$$

Claycomb

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 7, 3:07 AM MDT	Red Flag Warning	CYS		41 hr
Jul 7, 1:38 PM MDT	Fire Weather Watch	CYS		13 hr
Jul 7, 2:59 PM MDT	Special Weather Statement	CYS	Niobrara	31 min
Jul 7, 4:39 PM MDT	Severe Thunderstorm Warning	CYS	Goshen	51 min

Nearby

Severe Thunderstorm Warnings in Wyoming, 2021 Severe Thunderstorm Warnings in Nebraska, 2021 Every severe thunderstorm warning in 2021

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.