Alert archive / Nebraska / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 94, NWS Cheyenne, WY

July 9, 2021Box Butte County, Dawes County, Sioux County, Nebraska

NWS Cheyenne, WY issued this severe thunderstorm warning at Jul 9, 2021, 9:01 PM MDT for Box Butte County, Dawes County, Sioux County, Nebraska. It was in force for 44 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 9, 2021, 9:01 PM MDT (03:01 UTC)
Expired: Jul 9, 2021, 9:45 PM MDT
In force: 44 min
Issued by: NWS Cheyenne, WY
Area: Storm-based polygon
Tornado: Possible
Hail: 1.75 in
Wind: 70.0 mph

Counties Box Butte County, NE, Dawes County, NE, Sioux County, NE

The radar

The Cheyenne radar (KCYS), 177 km from the middle of the area, began a volume at 03:02 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, 9:23 PM MDT	TSTM WND GST 56	Agate Fossil Beds Natio, NE
Jul 9, 9:38 PM MDT	HAIL 1	6 W Hemingford, NE

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, 3.0 hours before the alert went out and 186 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.

339 
WUUS55 KCYS 100301
SVRCYS
NEC013-045-165-100345-
/O.NEW.KCYS.SV.W.0094.210710T0301Z-210710T0345Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Cheyenne WY
901 PM MDT Fri Jul 9 2021

The National Weather Service in Cheyenne has issued a

* Severe Thunderstorm Warning for...
  Western Box Butte County in the Panhandle of Nebraska...
  Southwestern Dawes County in the Panhandle of Nebraska...
  Central Sioux County in the Panhandle of Nebraska...

* Until 945 PM MDT.

* At 900 PM MDT, a severe thunderstorm was located 9 miles southeast
  of Harrison, or 38 miles west of Chadron, moving southeast at 75
  mph.

  HAZARD...Golf ball size hail and 70 mph wind gusts.

  SOURCE...Radar indicated.

  IMPACT...People and animals outdoors will be injured. Expect hail 
           damage to roofs, siding, windows, and vehicles. Expect 
           considerable tree damage. Wind damage is also likely to 
           mobile homes, roofs, and outbuildings.

* Locations impacted include...
  Crawford, Harrison, Kilpatrick Lake, Fort Robinson Campground, Box
  Butte Campground, Agate Bed National Monument, Flahertys Corner,
  Marsland and Fort Robinson.

This replaces the Tornado Warning which was previously in effect for 
the warned area. While not immediately likely, a tornado could still 
develop. Seek shelter immediately if you are in the path of this 
storm. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Prepare immediately for large hail and damaging winds. People outside
should move immediately to shelter inside a strong building. Stay
away from windows.

&&

LAT...LON 4257 10400 4280 10399 4285 10378 4255 10308
      4207 10312 4205 10362
TIME...MOT...LOC 0300Z 320DEG 63KT 4263 10370 

TORNADO...POSSIBLE
HAIL...1.75IN
WIND...70MPH
 
$$

Hammer

1 follow-up statement

352 
WWUS55 KCYS 100316
SVSCYS

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

NEC013-045-165-100345-
/O.CON.KCYS.SV.W.0094.000000T0000Z-210710T0345Z/
Box Butte NE-Dawes NE-Sioux NE-
916 PM MDT Fri Jul 9 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 945 PM MDT
FOR WESTERN BOX BUTTE...SOUTHWESTERN DAWES AND SOUTHERN SIOUX
COUNTIES...

At 915 PM MDT, a severe thunderstorm was located 7 miles northwest of
Flahertys Corner, or 38 miles southwest of Chadron, moving southeast
at 70 mph.

This is a very dangerous storm.

HAZARD...80 mph wind gusts and two inch hail.

SOURCE...Radar indicated.

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be heavily damaged. Expect 
         considerable damage to roofs, windows, and vehicles. 
         Extensive tree damage and power outages are likely.

Locations impacted include...
Crawford, Kilpatrick Lake, Fort Robinson Campground, Box Butte
Campground, Agate Bed National Monument, Flahertys Corner, Marsland
and Fort Robinson.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Prepare immediately for large hail and damaging winds. People outside
should move to a shelter, inside a strong building and away from
windows.

&&

LAT...LON 4250 10394 4251 10377 4256 10365 4270 10364
      4270 10343 4255 10308 4207 10312 4205 10362
TIME...MOT...LOC 0315Z 320DEG 62KT 4241 10350 

TORNADO...POSSIBLE
HAIL...2.00IN
WIND...80MPH
 
$$

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, 8:31 PM MDT	Tornado Warning	CYS	Sioux	44 min
Jul 9, 8:47 PM MDT	Severe Thunderstorm Warning	CYS	Dawes	43 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

Nearby

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.