Alert archive / Wyoming / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 140, NWS Cheyenne, WY

September 3, 2021Niobrara County, Wyoming

NWS Cheyenne, WY issued this severe thunderstorm warning at Sep 3, 2021, 6:20 PM MDT for Niobrara County, Wyoming. It was in force for 25 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: Sep 3, 2021, 6:20 PM MDT (00:20 UTC)
Expired: Sep 3, 2021, 6:45 PM MDT
In force: 25 min
Issued by: NWS Cheyenne, WY
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

County Niobrara County, WY

The radar

The Cheyenne radar (KCYS), 181 km from the middle of the area, began a volume at 00:20 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
Sep 3, 6:28 PM MDT	HAIL 1	7 E Lusk, WY	HAIL WAS LOCATED AT MILE MARKER 48 ON HIGHWAY 20.

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 00:00Z, 0.3 hours before the alert went out and 188 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: 2151 m above ground
0-6 km bulk shear: 60 kt
0-1 km storm-relative helicity: 134 m²/s²
0-3 km storm-relative helicity: 107 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

551 
WUUS55 KCYS 040020
SVRCYS
WYC027-040045-
/O.NEW.KCYS.SV.W.0140.210904T0020Z-210904T0045Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Cheyenne WY
620 PM MDT Fri Sep 3 2021

The National Weather Service in Cheyenne has issued a

* Severe Thunderstorm Warning for...
  Southeastern Niobrara County in east central Wyoming...

* Until 645 PM MDT.

* At 620 PM MDT, a severe thunderstorm was located near Lusk, moving
  northeast at 40 mph.

  HAZARD...60 mph wind gusts and quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Hail damage to vehicles is expected. Expect wind damage 
           to roofs, siding, and trees.

* This severe thunderstorm will remain over mainly rural areas of
  southeastern Niobrara County.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4263 10446 4268 10451 4290 10427 4285 10414
      4275 10409
TIME...MOT...LOC 0020Z 232DEG 33KT 4271 10441 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Charnick

2 follow-up statements

855 
WWUS55 KCYS 040027
SVSCYS

Severe Weather Statement
National Weather Service Cheyenne WY
627 PM MDT Fri Sep 3 2021

WYC027-040045-
/O.CON.KCYS.SV.W.0140.000000T0000Z-210904T0045Z/
Niobrara WY-
627 PM MDT Fri Sep 3 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 645 PM MDT
FOR SOUTHEASTERN NIOBRARA COUNTY...

At 627 PM MDT, a severe thunderstorm was located near Lusk, moving
northeast 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.

This severe thunderstorm will remain over mainly rural areas of
southeastern Niobrara County.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4269 10431 4276 10441 4282 10436 4290 10427
      4285 10414 4275 10409 4274 10413
TIME...MOT...LOC 0027Z 232DEG 33KT 4275 10434 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.50 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Charnick

421 
WWUS55 KCYS 040044
SVSCYS

Severe Weather Statement
National Weather Service Cheyenne WY
644 PM MDT Fri Sep 3 2021

WYC027-040054-
/O.EXP.KCYS.SV.W.0140.000000T0000Z-210904T0045Z/
Niobrara WY-
644 PM MDT Fri Sep 3 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN NIOBRARA COUNTY
WILL EXPIRE AT 645 PM MDT...
        
The storm which prompted the warning has weakened below severe
limits, and has exited the warned area. Therefore, the warning will
be allowed to expire.

LAT...LON 4269 10431 4276 10441 4282 10436 4290 10427
      4285 10414 4275 10409 4274 10413
TIME...MOT...LOC 0044Z 232DEG 33KT 4284 10418 

$$

Charnick

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 3, 6:11 PM MDT	Special Weather Statement	CYS	Niobrara	34 min
Sep 3, 6:30 PM MDT	Special Weather Statement	CYS	Niobrara	30 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.