Tornadoes · United States · Nebraska · 1997

F0 tornado, Hallam to Firth, Nebraska, May 7, 1997

From Hallam to Firth, this F0 tornado ran 1.2 miles across Lancaster County on May 7, 1997, touching down at 4:08 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
May 7, 1997
Touchdown
4:08 PM CDT (21:08 UTC)
Path length
1.2 miles (1.9 km)
Path width
20 yards (18 m)
Deaths
0
Injuries
0
County
Lancaster County
Touchdown point
40.520, -96.800
Lift-off point
40.520, -96.770
Record number
364

What the Weather Service recorded

Seven to ten homes in Princeton sustained roof damage and one hone had metal siding stripped off. Numerous trees were blown down near Princeton. Many windows were broken out from businesses and homes.

From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.

The warnings

No tornado warning for this county appears in the archive as in force at the moment the tornado touched down. One was issued for the county at another hour that day.

Issued (UTC)ExpiredProductOffice
21:04 UTC22:05 UTCSevere Thunderstorm WarningOAX
21:21 UTC22:00 UTCTornado WarningOAX

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 05:59 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 (KOAX), 12:00Z

9.1 hours before the tornado, 96 km from the path. May 7, 1997.

Skew-T log-pSkew-T log-p diagram, Omaha, NE at 12:00Z on 1997-05-07Temperature 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 -51275, lifted condensation level 963 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, Omaha, NE at 12:00Z on 1997-05-07The 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 155 square meters per square second, 0 to 6 km bulk shear 46 knots.193958Sfc1 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
-51275 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
963 m above ground
0-6 km bulk shear
46 kt
0-1 km bulk shear
18 kt
0-1 km storm-relative helicity
155 m²/s²
0-3 km storm-relative helicity
202 m²/s²
Significant tornado parameter
0.0
Supercell composite
5.1
0-3 km lapse rate
3.8 K/km

Open this sounding in Storm Lab

Omaha, NE (KOAX), 00:00Z

2.9 hours after it, 96 km from the path. May 8, 1997.

Skew-T log-pSkew-T log-p diagram, Omaha, NE at 00:00Z on 1997-05-08Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 27 joules per kilogram, CIN -156, lifted condensation level 1482 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, Omaha, NE at 00:00Z on 1997-05-08The 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 -57 square meters per square second, 0 to 6 km bulk shear 44 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
27 J/kg
Mixed-layer CIN
-156 J/kg
Surface CAPE
165 J/kg
Mixed-layer LCL
1482 m above ground
0-6 km bulk shear
44 kt
0-1 km bulk shear
10 kt
0-1 km storm-relative helicity
-57 m²/s²
0-3 km storm-relative helicity
38 m²/s²
Significant tornado parameter
-0.0
Supercell composite
-0.3
0-3 km lapse rate
6.8 K/km

Open this sounding in Storm Lab

The surface observations

Beatrice Municip (BIE), 24 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
19:10 UTC78.862.6210° 17 kt231009.5
19:30 UTC7764.4220° 12 kt1009.5
20:10 UTC78.862.6230° 12 kt1009.5
20:30 UTC78.862.6240° 15 kt1009.5
21:10 UTC80.662.6210° 11 kt151008.1
21:30 UTC80.662.6240° 10 kt1008.1
21:50 UTC80.662.6280° 7 kt1007.8
22:10 UTC80.657.220° 11 kt1007.5
22:30 UTC7757.230° 13 kt1007.1
22:50 UTC7755.420° 6 kt1007.5

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

The radar

The Omaha radar (KOAX), 96 km away, was scanning. The volume nearest the touchdown began at 21:06 UTC.

Open the radar archive at this moment, over the track

Reflectivity and velocity, decoded from the Level II archive in the browser. Volumes take a few seconds to open the first time.

This ground now

The live radar over the trackEvery 1997 tornado in NebraskaEvery tornado in Nebraska since 1950Warnings in force in Nebraska nowThe forecast where you are

The other tornadoes of May 7, 1997

16 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
May 74:12 PM CDTF0Lancaster, NE1.820
May 74:14 PM CDTF0Gage, NE2.020
May 74:20 PM CDTF1Lancaster, NE4.0100$300,000
May 74:31 PM CDTF0Lancaster, NE2.520
May 75:06 PM CDTF0Ottawa, KS5.023$30,000
May 77:00 PM CDTF0Grant, OK2.050$3,000
May 77:09 PM CDTF0Morris, KS0.123
May 77:39 PM CDTF0Gray, TX0.223
May 77:52 PM CDTF0Carson, TX0.523
May 77:52 PM CDTF0Grant, OK0.123
May 77:53 PM CDTF0Grant, OK0.123
May 77:58 PM CDTF0Kay, OK0.123
May 78:10 PM CDTF0Gray, TX1.050
May 79:05 PM CDTF0Wheeler, TX0.123
May 79:37 PM CDTF0Osage, OK0.130
May 710:02 PM CDTF0Osage, OK0.130

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.