Tornadoes · United States · Nebraska · 1991

F0 tornado, Polk County, Nebraska, May 29, 1991

This F0 tornado ran 1.0 miles across Polk County on May 29, 1991, touching down at 10:35 PM CDT and reaching 40 yards wide. It killed nobody, and did $500 to $5,000 of property damage.

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
May 29, 1991
Touchdown
10:35 PM CDT (03:35 UTC)
Path length
1.0 miles (1.6 km)
Path width
40 yards (37 m)
Deaths
0
Injuries
0
Property damage
$500 to $5,000
County
Polk County
Touchdown point
41.150, -97.550
Record number
708

The warnings

No tornado warning for this county appears in the archive as in force at the moment the tornado touched down.

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 Slight Risk. The outlook in force was issued at 06:19 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.

Omaha, NE (KOVN), 00:00Z

3.6 hours before the tornado, 100 km from the path. May 30, 1991.

Skew-T log-pSkew-T log-p diagram, Omaha, NE at 00:00Z on 1991-05-30Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 549 joules per kilogram, CIN -117, lifted condensation level 1066 meters above ground. Wind barbs in knots down the right edge.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. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Omaha, NE at 00:00Z on 1991-05-30The 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 43 square meters per square second, 0 to 6 km bulk shear 42 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
549 J/kg
Mixed-layer CIN
-117 J/kg
Surface CAPE
760 J/kg
Mixed-layer LCL
1066 m above ground
0-6 km bulk shear
42 kt
0-1 km bulk shear
11 kt
0-1 km storm-relative helicity
43 m²/s²
0-3 km storm-relative helicity
142 m²/s²
Significant tornado parameter
0.1
Supercell composite
0.8
0-3 km lapse rate
4.8 K/km

Open this sounding in Storm Lab

Omaha, NE (KOVN), 12:00Z

8.4 hours after it, 100 km from the path. May 30, 1991.

Skew-T log-pSkew-T log-p diagram, Omaha, NE at 12:00Z on 1991-05-30Temperature 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 -6876, lifted condensation level 1280 meters above ground. Wind barbs in knots down the right edge.LCL10008507005003002001001 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. The warm shading is its CAPE, the cool shading the inhibition it has to break through.
HodographHodograph, Omaha, NE at 12:00Z on 1991-05-30The 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 40 square meters per square second, 0 to 6 km bulk shear 33 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
-6876 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
1280 m above ground
0-6 km bulk shear
33 kt
0-1 km bulk shear
14 kt
0-1 km storm-relative helicity
40 m²/s²
0-3 km storm-relative helicity
50 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
4.0 K/km

Open this sounding in Storm Lab

The surface observations

Columbus Municipal (OLU), 37 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
02:00 UTC736560° 3 kt1007.1
03:00 UTC726480° 6 kt1006.1
04:00 UTC69640° 0 kt1006.4
05:00 UTC69640° 0 kt1006.4

From the Iowa Environmental Mesonet's archive of airport observations.

This ground now

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

The other tornadoes of May 29, 1991

20 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
May 295:15 PM CDTF1Concordia Parish, LA1.023$50,000 to $500,000
May 296:12 PM CDTF0Ochiltree, TX0.560$5,000 to $50,000
May 296:47 PM CDTF0Randall, TX0.550
May 296:51 PM CDTF0Potter, TX2.860
May 297:08 PM CDTF0Hutchinson, TX0.120
May 297:10 PM CDTF0Moore, TX2.040
May 296:40 PM MDTF0Washington, CO0.210
May 297:48 PM CDTF0Randall, TX0.230
May 296:56 PM MDTF1Washington, CO14.050
May 298:30 PM CDTF0Carson, TX0.120
May 297:40 PM MDTF0Washington, CO7.027$5,000 to $50,000
May 298:48 PM CDTF0Johnson, IA0.220$500 to $5,000
May 299:05 PM CDTF0Carson, TX0.230
May 298:36 PM MDTF0Perkins, NE0.223
May 298:46 PM MDTF0Phillips, CO0.210
May 298:51 PM MDTF0Yuma, CO0.210
May 2910:19 PM CDTF0Lincoln, NE0.223
May 2910:20 PM CDTF0Jones, SD0.550
May 2910:30 PM CDTF0Buffalo, NE0.530
May 2910:42 PM CDTF0Hall, NE0.230

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.