Alert archive / Wyoming / Tornado Warnings in 1991

Tornado Warning 2, NWS Cheyenne, WY

May 12, 1991Big Horn County, Wyoming

NWS Cheyenne, WY issued this tornado warning at May 12, 1991, 10:02 AM MDT for Big Horn County, Wyoming. It was in force for 28 min.

The area

The counties it named.

The facts

Issued
May 12, 1991, 10:02 AM MDT (16:02 UTC)
Expired
May 12, 1991, 10:30 AM MDT
In force
28 min
Issued by
NWS Cheyenne, WY
Area
Whole counties

County Big Horn County, WY

The nearest sounding before it

Lander/Hunt Fiel, WY (KLND), launched 12:00Z, 4.0 hours before the alert went out and 198 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-pSkew-T log-p diagram, Lander/Hunt Fiel, WY at 12:00Z on 1991-05-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Lander/Hunt Fiel, WY at 12:00Z on 1991-05-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 17 square meters per square second.1939Sfc1 km3 km6 kmRMLM
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
2684 m above ground
0-6 km bulk shear
8 kt
0-1 km storm-relative helicity
17 m²/s²
0-3 km storm-relative helicity
17 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KSHR 121602
TORSHR
WYC003-121630-
 
BULLETIN - EBS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE SHERIDAN WY
1002 AM MDT SUN MAY 12 1991
 
THE NATIONAL WEATHER SERVICE IN SHERIDAN HAS ISSUED A
TORNADO WARNING EFFECTIVE UNTIL 1030 AM MDT
FOR PEOPLE IN THE FOLLOWING LOCATION...
 
IN NORTH CENTRAL WYOMING
 
   ...SOUTH CENTRAL BIG HORN COUNTY
 
AT 950 AM...A TORNADO WAS SITED BY THE BIG HORN COUNTY HIGHWAY PATROL
JUST WEST OF THE CITY OF MANDERSON. THIS TORNADO WAS MOVING TO THE NORTH
TOWARD THE CITY OF BASIN.
 
 
IF YOU ARE IN THE PATH OF A TORNADO...THE SAFEST PLACE IS A
BASEMENT.  GET UNDER A WORKBENCH OR PIECE OF STURDY FURNITURE.
IF NO BASEMENT IS AVAILABLE...SEEK SHELTER IN AN INTERIO?R ROOM
SUCH AS A CLOSET ON THE LOWEST FLOOR.  USE BLANKETS...PILLOWS...
OR CUSHIONS TO COVER YOUR BODY.  AVOID WINDOWS.
 
NNNN

The office that day

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

IssuedProductOfficeCountiesLasted
May 11, 8:34 PM MDTSevere Thunderstorm WarningCYSPlatte56 min
May 12, 11:55 AM MDTSevere Thunderstorm WarningCYSSheridan35 min

Nearby

Tornado Warnings in Wyoming, 1991Every tornado warning in 1991Tornadoes in 1991

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive.