Tornadoes · United States · Kansas · 1991

F0 tornado, Pratt County, Kansas, April 12, 1991

This F0 tornado ran 2.0 miles across Pratt County on April 12, 1991, touching down at 5:05 PM CDT and reaching 20 yards wide. It killed nobody.

The rating scale

Tracks are drawn in the color of the rating. The Fujita scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.

  1. F040 to 72 mphthis tornado

    Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

  2. F173 to 112 mph

    Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

  3. F2113 to 157 mph

    Considerable damage. Roofs torn off well-built houses, frame homes shifted on their foundations, mobile homes destroyed, large trees snapped or uprooted, cars lifted off the ground.

  4. F3158 to 206 mph

    Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.

  5. F4207 to 260 mph

    Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

  6. F5261 to 318 mph

    Incredible damage. Strong frame houses swept off their foundations, car-sized missiles thrown more than 100 meters, steel-reinforced concrete badly damaged, high-rise buildings deformed.

  7. Unrated

    The survey recorded a tornado but could not put a number on it, most often because it crossed open country and damaged nothing a rating can be read from.

The record

Rating
F0
Date
April 12, 1991
Touchdown
5:05 PM CDT (22:05 UTC)
Path length
2.0 miles (3.2 km)
Path width
20 yards (18 m)
Deaths
0
Injuries
0
County
Pratt County
Touchdown point
37.650, -98.870
Record number
251

The warnings

2 minutes of warning. NWS DDC issued a tornado warning for this county at 22:03 UTC, 2 minutes before the tornado touched down, in force until 22:30 UTC.

Issued (UTC)ExpiredProductOffice
21:55 UTC22:45 UTCSevere Thunderstorm WarningDDC
22:03 UTC22:30 UTCTornado WarningDDC
22:40 UTC23:30 UTCSevere Thunderstorm WarningDDC
23:25 UTC00:30 UTCFlash Flood WarningDDC
23:25 UTC00:30 UTCTornado WarningDDC
23:32 UTC00:30 UTCSevere Thunderstorm WarningDDC
00:34 UTC01:15 UTCSevere Thunderstorm WarningDDC
00:37 UTC02:45 UTCFlash Flood WarningDDC
01:48 UTC02:45 UTCSevere Thunderstorm WarningDDC
02:37 UTC05:45 UTCFlash Flood WarningDDC
03:30 UTC04:30 UTCSevere Thunderstorm WarningDDC

Every warning and watch covering the touchdown point that day, from the Iowa Environmental Mesonet's archive of National Weather Service products. Lead time is measured from the issue of the warning in force to the touchdown time in the database, both of which were recorded to the minute by different people.

The forecast that day

The Storm Prediction Center had this point in a Moderate Risk. The outlook in force was issued at 07:04 UTC.

SPC's Day 1 convective outlook as it stood when the tornado began, read at the touchdown point. The same archive is on the radar archive.

The air that afternoon

The radiosonde launches on either side of the tornado, from the nearest station that was launching then, drawn and analyzed the way Storm Lab does: the same diagram, the same parcel and shear definitions SPC's mesoanalysis uses.

Dodge City, (KDDC), 12:00Z

10.1 hours before the tornado, 92 km from the path. April 12, 1991.

Skew-T log-pSkew-T log-p diagram, Dodge City, at 12:00Z on 1991-04-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 1583 joules per kilogram, CIN -47, lifted condensation level 695 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Dodge City, at 12:00Z on 1991-04-12The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity 133 square meters per square second, 0 to 6 km bulk shear 33 knots.1939587897Sfc1 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. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
1583 J/kg
Mixed-layer CIN
-47 J/kg
Surface CAPE
1551 J/kg
Mixed-layer LCL
695 m above ground
0-6 km bulk shear
33 kt
0-1 km bulk shear
26 kt
0-1 km storm-relative helicity
133 m²/s²
0-3 km storm-relative helicity
163 m²/s²
Significant tornado parameter
0.7
Supercell composite
4.3
0-3 km lapse rate
5.6 K/km

Open this sounding in Storm Lab

Dodge City, (KDDC), 00:00Z

1.9 hours after it, 92 km from the path. April 13, 1991.

Skew-T log-pSkew-T log-p diagram, Dodge City, at 00:00Z on 1991-04-13Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 0 joules per kilogram, CIN -8847, lifted condensation level 3500 meters above ground. Wind barbs in knots down the right edge.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Dodge City, at 00:00Z on 1991-04-13The wind through the lowest 10 kilometers as a curve, rings every 10 meters per second labeled in knots. Zero to 1 km storm-relative helicity -22 square meters per square second, 0 to 6 km bulk shear 51 knots.19395878Sfc1 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. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
-8847 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
3500 m above ground
0-6 km bulk shear
51 kt
0-1 km bulk shear
3 kt
0-1 km storm-relative helicity
-22 m²/s²
0-3 km storm-relative helicity
184 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
9.2 K/km

Open this sounding in Storm Lab

This ground now

The live radar over the trackEvery 1991 tornado in KansasEvery tornado in Kansas since 1950Warnings in force in Kansas nowThe forecast where you are

The other tornadoes of April 12, 1991

23 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
April 127:40 AM CDTF2Bossier Parish, LA15.0100$50,000 to $500,000
April 123:22 PM CDTF2Major, OK9.0300$5,000 to $50,000
April 123:52 PM CDTF0Garfield, OK0.120
April 124:05 PM CDTF0Canadian, OK1.030
April 124:20 PM CDTF2Garfield, OK6.050$5,000 to $50,000
April 124:33 PM CDTF0Garfield, OK2.530
April 124:37 PM CDTF3Garfield, OK9.0800$50,000 to $500,000
April 124:45 PM CDTF0Kingfisher, OK1.030
April 125:21 PM CDTF3Grant, OK9.5500$500,000 to $5 million
April 125:22 PM CDTF0Clay, NE0.523
April 125:40 PM CDTF0Pratt, KS1.317
April 125:40 PM CDTF2Somervell, TX2.0100$50,000 to $500,000
April 125:55 PM CDTF2Somervell, TX3.0150
April 125:59 PM CDTF0Lincoln, KS1.050
April 126:30 PM CDTF0Kingfisher, OK0.120
April 126:45 PM CDTF0Cloud, KS1.050$500 to $5,000
April 126:45 PM CDTF2Johnson, TX2.0200$50,000 to $500,000
April 127:05 PM CDTF2Johnson, TX1.5300$5,000 to $50,000
April 127:13 PM CDTF1Kingfisher, OK2.040
April 127:51 PM CDTF2Johnson, TX0.210$5,000 to $50,000
April 128:00 PM CDTF0Pickens, AL0.310$50,000 to $500,000
April 128:40 PM CDTF0Johnson, TX0.210$500 to $5,000
April 128:55 PM CDTF1Johnson, TX0.210$5,000 to $50,000

What this means

Ratings are the survey's, read off the damage rather than measured; the rating scale is above. Tornado counts rise through the record as reporting improved, so a year in the 1950s is not comparable with one today except for the strongest tornadoes, which were always noticed.

Sources

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.