Alert archive / Nebraska / Tornado Warnings in 1991

Tornado Warning 40, NWS North Platte, NE

July 20, 1991Knox County, Nebraska

NWS North Platte, NE issued this tornado warning at Jul 20, 1991, 9:07 PM CDT for Knox County, Nebraska. It was in force for 53 min.

The area

The counties it named.

The facts

Issued
Jul 20, 1991, 9:07 PM CDT (02:07 UTC)
Expired
Jul 20, 1991, 10:00 PM CDT
In force
53 min
Issued by
NWS North Platte, NE
Area
Whole counties

County Knox County, NE

The nearest sounding before it

Omaha, NE (KOVN), launched 00:00Z, 2.1 hours before the alert went out and 193 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, Omaha, NE at 00:00Z on 1991-07-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1332 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Omaha, NE at 00:00Z on 1991-07-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 29 square meters per square second.1939Sfc1 km3 km6 km9 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
1332 J/kg
Mixed-layer CIN
-197 J/kg
Mixed-layer LCL
1674 m above ground
0-6 km bulk shear
16 kt
0-1 km storm-relative helicity
29 m²/s²
0-3 km storm-relative helicity
150 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 KOFK 210207
TOROFK
NEC107-210300-

BULLETIN - IMMEDIATE BROADCAST REQUESTED/EBS ACTIVATION REQUESTED 
TORNADO WARNING 
NATIONAL WEATHER SERVICE NORFOLK NE
907 PM CDT SAT JUL 20 1991

THE NATIONAL WEATHER SERVICE HAS ISSUED A TORNADO WARNING 
EFFECTIVE UNTIL 1000 PM CDT FOR PEOPLE IN THE FOLLOWING COUNTY

   IN THE NORTHEAST PART OF NEBRASKA
      NORTHERN KNOX

AT 905 PM CDT RADAR INDICATED A POSSIBLE TORNADO ENTERING THE
NORTHWEST CORNER OF KNOX COUNTY...35 MILES NORTHEAST OF O NEILL...
NEAR VERDEL.  THE STORM WAS MOVING SOUTHEAST AT 15 MPH AND IF YOU
ARE IN THE TOWNS OF VERDEL...NIOBRARA...AND SANTEE YOU SHOULD BE
PREPARED TO TAKE COVER TO SAVE YOUR LIFE.

THIS IS A DANGEROUS STORM SITUATION.  ACT QUICKLY.  IF YOU ARE IN
THE PATH OF THIS TORNADO TAKE SHELTER BELOW GROUND IF POSSIBLE.
OTHERWISE...GO TO A SMALL INTERIOR ROOM ON THE LOWEST FLOOR.  AVOID
WINDOWS.  ABANDON CARS AND MOBILE HOMES...TAKE COVER IN A REINFORCED
BUILDING OR GET INTO A DITCH OR CULVERT.

 BOWMAN

What forecasters said that day

The local office's own words before this tornado warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

In the hours before

Special weather statement, Jul 20, 4:39 PM CDT, 4 hours 28 minutes before
NEZ007-202230-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE NORTH PLATTE NE
435 PM CDT SAT JUL 20 1991

AT 430 PM CDT RADAR SHOWED A SMALL AREA OF SCATTERED THUNDERSTORMS
WHICH HAD DEVELOPED ACROSS NORTHWEST CUSTER COUNTY.  THIS AREA
WAS LOCATED FROM 30 MILES NORTHEAST OF NORTH PLATTE NEAR ARNOLD...
TO 50 MILES NORTHEAST OF NORTH PLATTE...NEAR THE TOWN OF ANSELMO.

ONE THUNDERSTORM WITH VERY HEAVY RAIN WAS LOCATED ABOUT 5 MILES
NORTHEAST OF ANSELMO.

THE AREA OF THUNDERSTORMS HAD SHOWN LITTLE MOVEMENT...BUT INDIVIDUAL
THUNDERSTORMS WERE MOVING NORTHEAST AT 15 MILES AN HOUR.  PERSONS
IN THE NORTHWEST QUARTER OF CUSTER COUNTY CAN EXPECT BRIEF
HEAVY RAIN AND GUSTY WINDS TO BE ASSOCIATED WITH THIS NARROW BAND OF
THUNDERSTORMS.

SC

The office that day

Everything else NWS North Platte, NE issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 21, 4:58 PM CDTSevere Thunderstorm WarningLBFAntelope32 min
Jul 21, 5:30 PM CDTSevere Thunderstorm WarningLBFAntelope, Pierce60 min

Nearby

Tornado Warnings in Nebraska, 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.