Alert archive / Nebraska / Tornado Warnings in 2021

Tornado Warning 5, NWS Cheyenne, WY

July 9, 2021Sioux County, Nebraska; Niobrara County, Wyoming

NWS Cheyenne, WY issued this tornado warning at Jul 9, 2021, 8:31 PM MDT for Sioux County, Nebraska; Niobrara County, Wyoming. It was in force for 44 min. 3 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 9, 2021, 8:31 PM MDT (02:31 UTC)
Expired: Jul 9, 2021, 9:15 PM MDT
In force: 44 min
Issued by: NWS Cheyenne, WY
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 2.75 in

Counties Sioux County, NE, Niobrara County, WY

The radar

The Rapid City radar (KUDX), 177 km from the middle of the area, began a volume at 02:30 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 9, 8:38 PM MDT	TSTM WND GST 61	13 Nnw Harrison, NE
Jul 9, 8:40 PM MDT	TSTM WND GST 63	Harrison, NE
Jul 9, 9:00 PM MDT	TORNADO	17 N Van Tassell, WY	EMERGENCY MANAGER IN NIOBRARA COUNTY REPORTED A TORNADO ON S-BAR ROAD NORTHEAST OF LUSK. DAMAGE TO HOUSE ROOF WAS REPORTED

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
Jul 9, 2:16 PM MDT	Severe Thunderstorm Watch	SPC	9 hr

The nearest sounding before it

Rapid City, SD (KUNR), launched 00:00Z, 2.5 hours before the alert went out and 170 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: 240 J/kg
Mixed-layer CIN: -260 J/kg
Mixed-layer LCL: 2327 m above ground
0-6 km bulk shear: 56 kt
0-1 km storm-relative helicity: -35 m²/s²
0-3 km storm-relative helicity: 76 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.0

Open this sounding in Storm Lab

The text

As transmitted.

122 
WFUS55 KCYS 100231
TORCYS
NEC165-WYC027-100315-
/O.NEW.KCYS.TO.W.0005.210710T0231Z-210710T0315Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Cheyenne WY
831 PM MDT Fri Jul 9 2021

The National Weather Service in Cheyenne has issued a

* Tornado Warning for...
  Northern Sioux County in the Panhandle of Nebraska...
  Southeastern Niobrara County in east central Wyoming...

* Until 915 PM MDT.
    
* At 830 PM MDT, a severe thunderstorm capable of producing a tornado
  was located 15 miles northwest of Harrison, or 21 miles east of
  Lusk, moving southeast at 40 mph.

  HAZARD...Tornado and baseball size hail.

  SOURCE...Radar indicated rotation.

  IMPACT...Flying debris will be dangerous to those caught without 
           shelter. Mobile homes will be damaged or destroyed. 
           Damage to roofs, windows, and vehicles will occur.  Tree 
           damage is likely.

* Locations impacted include...
  Harrison.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

Tornadoes are extremely difficult to see and confirm at night. Do not
wait to see or hear the tornado. TAKE COVER NOW!

&&

LAT...LON 4300 10405 4300 10389 4271 10354 4249 10389
      4255 10406 4261 10406 4261 10419 4283 10435
      4305 10406
TIME...MOT...LOC 0230Z 322DEG 34KT 4287 10405 

TORNADO...RADAR INDICATED
HAIL...2.75IN

$$

Hammer

2 follow-up statements

969 
WWUS55 KCYS 100241
SVSCYS

Severe Weather Statement
National Weather Service Cheyenne WY
841 PM MDT Fri Jul 9 2021

NEC165-WYC027-100315-
/O.CON.KCYS.TO.W.0005.000000T0000Z-210710T0315Z/
Sioux NE-Niobrara WY-
841 PM MDT Fri Jul 9 2021

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 915 PM MDT FOR NORTHERN
SIOUX AND SOUTHEASTERN NIOBRARA COUNTIES...
    
At 840 PM MDT, a severe thunderstorm capable of producing a tornado
was located near Harrison, or 24 miles east of Lusk, moving 
southeast at 55 mph. A second potentially tornadic circulation was 
located near Van Tassel. 

SEEK SHELTER IMMEDIATELY IF IN HARRISON OR VAN TASSEL!

HAZARD...Tornado and baseball size hail.

SOURCE...Radar indicated rotation.

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be damaged or destroyed. Damage 
         to roofs, windows, and vehicles will occur.  Tree damage is 
         likely.

Locations impacted include...
Harrison and Van Tassell. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

Tornadoes are extremely difficult to see and confirm at night. Do not
wait to see or hear the tornado. TAKE COVER NOW!

&&

LAT...LON 4300 10405 4300 10389 4271 10354 4249 10389
      4255 10406 4261 10406 4261 10419 4283 10435
      4285 10406
TIME...MOT...LOC 0240Z 321DEG 49KT 4271 10397 

TORNADO...RADAR INDICATED
HAIL...2.75IN

$$

Hammer

400 
WWUS55 KCYS 100251
SVSCYS

Severe Weather Statement
National Weather Service Cheyenne WY
851 PM MDT Fri Jul 9 2021

WYC027-100301-
/O.CAN.KCYS.TO.W.0005.000000T0000Z-210710T0315Z/
Niobrara WY-
851 PM MDT Fri Jul 9 2021

...THE TORNADO WARNING FOR SOUTHEASTERN NIOBRARA COUNTY IS
CANCELLED...
    
The tornadic thunderstorm which prompted the warning has moved out 
of the warned area. therefore, the warning has been cancelled.

A Severe Thunderstorm Watch remains in effect until 1100 PM MDT for
the Panhandle of Nebraska.

LAT...LON 4290 10404 4291 10379 4271 10354 4249 10389
      4255 10404
TIME...MOT...LOC 0251Z 319DEG 33KT 4266 10385 

$$

NEC165-100315-
/O.CON.KCYS.TO.W.0005.000000T0000Z-210710T0315Z/
Sioux NE-
851 PM MDT Fri Jul 9 2021

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 915 PM MDT FOR NORTHERN
SIOUX COUNTY...
    
At 851 PM MDT, a severe thunderstorm capable of producing a tornado
was located over Harrison, or 31 miles east of Lusk, moving southeast
at 40 mph.

HAZARD...Tornado and baseball size hail.

SOURCE...Radar indicated rotation.

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be damaged or destroyed. Damage 
         to roofs, windows, and vehicles will occur.  Tree damage is 
         likely.

Locations impacted include...
Harrison.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

Tornadoes are extremely difficult to see and confirm at night. Do not
wait to see or hear the tornado. TAKE COVER NOW!

&&

LAT...LON 4290 10404 4291 10379 4271 10354 4249 10389
      4255 10404
TIME...MOT...LOC 0251Z 319DEG 33KT 4266 10385 

TORNADO...RADAR INDICATED
HAIL...2.75IN

$$

Hammer

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 9, 6:07 PM MDT	Tornado Warning	CYS	Morrill	26 min
Jul 9, 8:04 PM MDT	Severe Thunderstorm Warning	CYS	Sioux	41 min
Jul 9, 8:47 PM MDT	Severe Thunderstorm Warning	CYS	Dawes	43 min
Jul 9, 9:01 PM MDT	Severe Thunderstorm Warning	CYS	Box Butte, Dawes, Sioux	44 min
Jul 9, 9:22 PM MDT	Severe Thunderstorm Warning	CYS	Box Butte, Dawes	38 min
Jul 9, 9:33 PM MDT	Severe Thunderstorm Warning	CYS	Box Butte, Dawes, Morrill, Sioux	57 min
Jul 9, 7:25 PM MDT	Severe Thunderstorm Warning	CYS	Niobrara	50 min
Jul 9, 9:47 PM MDT	Special Weather Statement	CYS	Platte	28 min
Jul 9, 10:19 PM MDT	Severe Thunderstorm Warning	CYS	Goshen, Platte	41 min
Jul 9, 10:58 PM MDT	Special Weather Statement	CYS	Goshen	32 min

Nearby

Tornado Warnings in Nebraska, 2021 Tornado Warnings in Wyoming, 2021 Every tornado warning in 2021 Tornadoes 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.