Alert archive / Wyoming / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 4, NWS Cheyenne, WY

May 20, 2021Goshen County, Niobrara County, Platte County, Wyoming

NWS Cheyenne, WY issued this severe thunderstorm warning at May 20, 2021, 7:27 PM MDT for Goshen County, Niobrara County, Platte County, Wyoming. It was in force for 35 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: May 20, 2021, 7:27 PM MDT (01:27 UTC)
Expired: May 20, 2021, 8:02 PM MDT
In force: 35 min
Issued by: NWS Cheyenne, WY
Area: Storm-based polygon
Hail: 1.5 in
Wind: 60.0 mph

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

The radar

The Cheyenne radar (KCYS), 145 km from the middle of the area, began a volume at 01:29 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

Rapid City, SD (KUNR), launched 00:00Z, 1.5 hours before the alert went out and 221 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: 296 J/kg
Mixed-layer CIN: -70 J/kg
Mixed-layer LCL: 2384 m above ground
0-6 km bulk shear: 17 kt
0-1 km storm-relative helicity: 0 m²/s²
0-3 km storm-relative helicity: 9 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

722 
WUUS55 KCYS 210127
SVRCYS
WYC015-027-031-210215-
/O.NEW.KCYS.SV.W.0004.210521T0127Z-210521T0215Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Cheyenne WY
727 PM MDT Thu May 20 2021

The National Weather Service in Cheyenne has issued a

* Severe Thunderstorm Warning for...
  South central Niobrara County in east central Wyoming...
  Northwestern Goshen County in southeastern Wyoming...
  Northeastern Platte County in southeastern Wyoming...

* Until 815 PM MDT.

* At 727 PM MDT, a severe thunderstorm was located 7 miles south of 
  Jay Em, or 22 miles northwest of Torrington, moving north at 40 
  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...
  Rawhide Buttes 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 4224 10432 4227 10447 4266 10480 4273 10422
TIME...MOT...LOC 0127Z 166DEG 39KT 4236 10436 

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

Claycomb

1 follow-up statement

945 
WWUS55 KCYS 210202
SVSCYS

Severe Weather Statement
National Weather Service Cheyenne WY
802 PM MDT Thu May 20 2021

WYC015-027-031-210212-
/O.CAN.KCYS.SV.W.0004.000000T0000Z-210521T0215Z/
Niobrara WY-Goshen WY-Platte WY-
802 PM MDT Thu May 20 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTH CENTRAL NIOBRARA...
NORTHWESTERN GOSHEN AND NORTHEASTERN PLATTE COUNTIES IS CANCELLED...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning has been cancelled.

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

LAT...LON 4224 10432 4227 10447 4266 10480 4273 10422
TIME...MOT...LOC 0158Z 166DEG 39KT 4273 10449 

$$

Claycomb

The office that day

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

Issued	Product	Office	Counties	Lasted
May 20, 7:07 PM MDT	Severe Thunderstorm Warning	CYS	Goshen	38 min

Nearby

Severe Thunderstorm Warnings in Wyoming, 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.