Alert archive / Nebraska / Tornado Warnings in 2017

Tornado Warning 28, NWS Cheyenne, WY

August 12, 2017Box Butte County, Morrill County, Nebraska

NWS Cheyenne, WY issued this tornado warning at Aug 12, 2017, 3:20 PM MDT for Box Butte County, Morrill County, Nebraska. It was in force for 26 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: Aug 12, 2017, 3:20 PM MDT (21:20 UTC)
Expired: Aug 12, 2017, 3:46 PM MDT
In force: 26 min
Issued by: NWS Cheyenne, WY
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 2.5 in

Counties Box Butte County, NE, Morrill County, NE

The radar

The Cheyenne radar (KCYS), 181 km from the middle of the area, began a volume at 21:23 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
Aug 12, 3:30 PM MDT	HAIL 1.25	5 S Alliance, NE	COVERS HWY 385 SOUTH OF ALLIANCE.
Aug 12, 3:33 PM MDT	HAIL 1.75	10 Sw Alliance, NE	GOLF BALL HAIL ALONG HIGHWAY 385. SEVERAL CARS ON SIDE OF ROAD WITH BROKEN WINDOWS.
Aug 12, 3:34 PM MDT	HAIL 1.75	10 Sw Alliance, NE	SEVERAL CARS ALONG THE SIDE OF HWY 385 WITH BROKEN WINDSHIELDS.

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
Aug 12, 2:59 PM MDT	Severe Thunderstorm Watch	SPC	7 hr

The nearest sounding before it

N. Platte/Lee Bi, NE (KLBF), launched 12:00Z, 9.3 hours before the alert went out and 206 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: 1071 m above ground
0-6 km bulk shear: 29 kt
0-1 km storm-relative helicity: 67 m²/s²
0-3 km storm-relative helicity: 123 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

As transmitted.

956 
WFUS55 KCYS 122120
TORCYS
NEC013-123-122200-
/O.NEW.KCYS.TO.W.0028.170812T2120Z-170812T2200Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Cheyenne WY
320 PM MDT SAT AUG 12 2017

The National Weather Service in Cheyenne has issued a

* Tornado Warning for...
  Southeastern Box Butte County in the Panhandle of Nebraska...
  Northeastern Morrill County in the Panhandle of Nebraska...

* Until 400 PM MDT
    
* At 320 PM MDT, a severe thunderstorm capable of producing a 
  tornado was located 5 miles southwest of Alliance, moving 
  southeast at 25 mph.

  HAZARD...Tornado and tennis ball 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. 

* This tornadic thunderstorm will remain over mainly rural areas of
  southeastern Box Butte and northeastern Morrill Counties.

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.

Heavy rainfall may hide this tornado. Do not wait to see or hear the
tornado. TAKE COVER NOW!

&&

LAT...LON 4168 10287 4201 10313 4212 10296 4200 10267
      4182 10268
TIME...MOT...LOC 2120Z 314DEG 22KT 4198 10298 

TORNADO...RADAR INDICATED
HAIL...2.50IN

$$

Hammer

2 follow-up statements

560 
WWUS55 KCYS 122128
SVSCYS

Severe Weather Statement
National Weather Service Cheyenne WY
328 PM MDT SAT AUG 12 2017

NEC013-123-122200-
/O.CON.KCYS.TO.W.0028.000000T0000Z-170812T2200Z/
Box Butte NE-Morrill NE-
328 PM MDT SAT AUG 12 2017

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 400 PM MDT FOR
SOUTHEASTERN BOX BUTTE AND NORTHEASTERN MORRILL COUNTIES...
    
At 326 PM MDT, a severe thunderstorm capable of producing a tornado
was located 8 miles southwest of Alliance Airport, or 9 miles south
of Alliance, moving southeast at 25 mph.

HAZARD...Tornado and three inch 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...
Highway 385 south of Alliance near the Morrill county line. 
Otherwise, this storm will remain over mainly rural areas of Box 
Butte and Morrill counties. 

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.

Heavy rainfall may hide this tornado. Do not wait to see or hear the
tornado. TAKE COVER NOW!

&&

LAT...LON 4168 10287 4201 10313 4212 10296 4200 10267
      4182 10268
TIME...MOT...LOC 2126Z 311DEG 22KT 4197 10293 

TORNADO...RADAR INDICATED
HAIL...3.00IN

$$

Hammer

026 
WWUS55 KCYS 122146
SVSCYS

Severe Weather Statement
National Weather Service Cheyenne WY
346 PM MDT SAT AUG 12 2017

NEC013-123-122156-
/O.CAN.KCYS.TO.W.0028.000000T0000Z-170812T2200Z/
Box Butte NE-Morrill NE-
346 PM MDT SAT AUG 12 2017

...THE TORNADO WARNING FOR SOUTHEASTERN BOX BUTTE AND NORTHEASTERN
MORRILL COUNTIES IS CANCELLED...
    
The tornado threat has diminished and the Tornado Warning has been
cancelled. However, large hail and damaging winds remain likely and a
Severe Thunderstorm Warning remains in effect for Morrill county. 

A severe thunderstorm watch remains in effect until 1100 PM MDT for
the Panhandle of Nebraska.

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

LAT...LON 4168 10287 4201 10313 4212 10296 4200 10267
      4182 10268
TIME...MOT...LOC 2142Z 314DEG 22KT 4188 10281 

$$

Hammer

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 12, 1:36 PM MDT	Severe Thunderstorm Warning	CYS	Box Butte, Dawes, Sioux	39 min
Aug 12, 2:14 PM MDT	Severe Thunderstorm Warning	CYS	Box Butte	46 min
Aug 12, 2:54 PM MDT	Severe Thunderstorm Warning	CYS	Box Butte, Morrill	51 min
Aug 12, 3:45 PM MDT	Severe Thunderstorm Warning	CYS	Morrill	45 min
Aug 12, 3:50 PM MDT	Severe Thunderstorm Warning	CYS	Kimball	40 min
Aug 12, 4:29 PM MDT	Areal Flood Advisory	CYS	Kimball	3 hr
Aug 12, 4:29 PM MDT	Severe Thunderstorm Warning	CYS	Morrill	31 min
Aug 12, 5:00 PM MDT	Special Weather Statement	CYS	Cheyenne	45 min

Nearby

Tornado Warnings in Nebraska, 2017 Every tornado warning in 2017 Tornadoes in 2017

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.