Alert archive / Nebraska / Tornado Warnings in 1998

Tornado Warning 7, NWS Cheyenne, WY

May 21, 1998Scotts Bluff County, Sioux County, Nebraska

NWS Cheyenne, WY issued this tornado warning at May 21, 1998, 10:55 AM MDT for Scotts Bluff County, Sioux County, Nebraska. It was in force for 30 min. 4 reports came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued: May 21, 1998, 10:55 AM MDT (16:55 UTC)
Expired: May 21, 1998, 11:25 AM MDT
In force: 30 min
Issued by: NWS Cheyenne, WY
Area: Whole counties

Counties Scotts Bluff County, NE, Sioux County, NE

The radar

The Cheyenne radar (KCYS), 144 km from the middle of the area, began a volume at 16:55 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
May 21, 10:58 AM MDT	Tornado F0	Morrill, NE	A tornado moved across open country to the south and southeast of Morrill, before dissipating.
May 21, 11:03 AM MDT	Tornado F2	Morrill, NE
May 21, 11:17 AM MDT	Tornado F1	Mitchell, NE	A brief tornado touched down just to the north of Mitchell and uprooted several trees near the golf course.
May 21, 11:30 AM MDT	Tornado F0	Mitchell, NE	A brief weak tornado moved across open country south of Mitchell then dissipated.

NCEI Storm Data entries that began inside the alert's area while it was in force. Before 2003 the local storm report archive is thin, so this is the record of what happened rather than what was phoned in.

The nearest sounding before it

Rapid City, SD (KUNR), launched 12:00Z, 4.9 hours before the alert went out and 222 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: 33 J/kg
Mixed-layer CIN: -254 J/kg
Mixed-layer LCL: 704 m above ground
0-6 km bulk shear: 29 kt
0-1 km storm-relative helicity: 98 m²/s²
0-3 km storm-relative helicity: 57 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000 
TTAA00 KCYS 211654 RRA
TORCYS
NEC157-165-211725-

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE CHEYENNE WY
1055 AM MDT THU MAY 21 1998

THE NATIONAL WEATHER SERVICE IN CHEYENNE HAS ISSUED A

* TORNADO WARNING FOR...
  EXTREME SOUTHERN SIOUX COUNTY IN NORTHWESTERN NEBRASKA PANHANDLE
  NORTHWESTERN SCOTTS BLUFF COUNTY IN WESTERN NEBRASKA PANHANDLE

* UNTIL 1125 AM MDT

* AT 1050 AM MDT... SPOTTERS INDICATED A TORNADO JUST EAST OF HENRY OR
  20 MILES NORTHWEST OF SCOTTSBLUFF... MOVING EAST AT 25 MPH.

* THE TORNADO IS EXPECTED TO BE NEAR...
  MORRILL BY 1105 AM MDT

A TORNADO IS ON THE GROUND! GO TO THE BASEMENT! IF A BASEMENT IS NOT
AVAILABLE...GO TO A SMALL INTERIOR ROOM ON THE LOWEST FLOOR!

JLH


&

The office that day

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

Issued	Product	Office	Counties	Lasted
May 20, 6:10 PM MDT	Severe Thunderstorm Warning	CYS	Morrill	30 min
May 20, 6:29 PM MDT	Tornado Warning	CYS	Morrill	31 min
May 20, 6:59 PM MDT	Tornado Warning	CYS	Morrill	31 min
May 20, 7:39 PM MDT	Severe Thunderstorm Warning	CYS	Cheyenne	31 min
May 20, 7:54 PM MDT	Tornado Warning	CYS	Cheyenne	31 min
May 20, 8:49 PM MDT	Severe Thunderstorm Warning	CYS	Cheyenne	31 min
May 21, 4:57 AM MDT	Severe Thunderstorm Warning	CYS	Box Butte	48 min
May 21, 5:48 AM MDT	Severe Thunderstorm Warning	CYS	Box Butte	37 min
May 21, 11:30 AM MDT	Tornado Warning	CYS	Scotts Bluff	35 min

Nearby

Tornado Warnings in Nebraska, 1998 Every tornado warning in 1998 Tornadoes in 1998

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.