Tornadoes · United States · Nebraska · 2001

F1 tornado, Berwyn, Nebraska, April 6, 2001

This F1 tornado ran 1.0 miles across Custer County on April 6, 2001, touching down at 11:20 PM CDT and reaching 100 yards wide. It killed nobody, and did $100,000 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 mph

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

  2. F173 to 112 mphthis tornado

    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
F1
Date
April 6, 2001
Touchdown
11:20 PM CDT (04:20 UTC)
Path length
1.0 miles (1.6 km)
Path width
100 yards (91 m)
Deaths
0
Injuries
0
Property damage
$100,000
County
Custer County
Touchdown point
41.350, -99.520
Lift-off point
41.350, -99.520
Record number
38

What the Weather Service recorded

An F1 tornado developed just west of Berwyn in southeast Custer County. In the minute and a half that it was on the ground, it picked up a van on Highway 2, turned it around, and shattered the windows. The occupants of the van were uninjured. Numerous trees were uprooted or snapped off, and the roof was torn off a farm house. Another farmstead suffered damage to the house and barn. There were also irrigation pipes tossed around and bent.

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.

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 01:25 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.

N. Platte/Lee Bi, NE (KLBF), 00:00Z

4.3 hours before the tornado, 94 km from the path. April 7, 2001.

Skew-T log-pSkew-T log-p diagram, N. Platte/Lee Bi, NE at 00:00Z on 2001-04-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 363 joules per kilogram, CIN -197, lifted condensation level 516 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, N. Platte/Lee Bi, NE at 00:00Z on 2001-04-07The 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 507 square meters per square second, 0 to 6 km bulk shear 79 knots.1939587897117136Sfc1 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
363 J/kg
Mixed-layer CIN
-197 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
516 m above ground
0-6 km bulk shear
79 kt
0-1 km bulk shear
43 kt
0-1 km storm-relative helicity
507 m²/s²
0-3 km storm-relative helicity
554 m²/s²
Significant tornado parameter
0.0
Supercell composite
10.4
0-3 km lapse rate
4.1 K/km

Open this sounding in Storm Lab

N. Platte/Lee Bi, NE (KLBF), 12:00Z

7.7 hours after it, 94 km from the path. April 7, 2001.

Skew-T log-pSkew-T log-p diagram, N. Platte/Lee Bi, NE at 12:00Z on 2001-04-07Temperature 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 -74031, lifted condensation level 1135 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, N. Platte/Lee Bi, NE at 12:00Z on 2001-04-07The 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 -16 square meters per square second, 0 to 6 km bulk shear 20 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
-74031 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
1135 m above ground
0-6 km bulk shear
20 kt
0-1 km bulk shear
40 kt
0-1 km storm-relative helicity
-16 m²/s²
0-3 km storm-relative helicity
47 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
5.3 K/km

Open this sounding in Storm Lab

The surface observations

Broken Bow Municipal (BBW), 14 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
02:28 UTC5955.4180° 23 kt34990.5+TSRA BR
02:53 UTC5755130° 15 kt22988.5VCTS RA BR
03:01 UTC55.455.4120° 14 kt23987.8VCTS -RA
03:22 UTC55.453.6130° 9 kt988.5
03:53 UTC565480° 7 kt985.8-RA
04:04 UTC57.255.4100° 10 kt984.4VCTS -RA
04:26 UTC57.255.480° 10 kt20982.1VCTS +RA BR
04:37 UTC57.255.4140° 6 kt981.7VCTS +RA BR
04:46 UTC57.255.4170° 15 kt19982.1-RA
04:53 UTC5754190° 20 kt26982.1
05:33 UTC53.651.8190° 25 kt31981.4BR
05:53 UTC5350190° 25 kt36980.7-RA

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

The radar

The North Platte radar (KLNX), 111 km away, was scanning. The volume nearest the touchdown began at 04:07 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 2001 tornado in NebraskaEvery tornado in Nebraska since 1950Warnings in force in Nebraska nowThe forecast where you are

The other tornadoes of April 6, 2001

5 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
April 65:10 PM CDTF2Morton, KS6.63502$100,000
April 65:38 PM CDTF1Stevens, KS7.0150$100,000
April 65:47 PM CDTF2Grant, KS14.0150$240,000
April 66:00 PM CDTF1Ochiltree, TX10.0100$500,000
April 612:47 AM CDTF1Holt, NE1.0100$10,000

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.