Tornadoes · United States · North Dakota · 2001

F2 tornado, Benson County, North Dakota, August 8, 2001

This F2 tornado ran 2.0 miles across Benson County on August 8, 2001, touching down at 6:18 PM CDT and reaching 250 yards wide. It killed nobody, and did $300,000 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 mph

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

  3. F2113 to 157 mphthis tornado

    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
F2
Date
August 8, 2001
Touchdown
6:18 PM CDT (23:18 UTC)
Path length
2.0 miles (3.2 km)
Path width
250 yards (229 m)
Deaths
0
Injuries
0
Property damage
$300,000
County
Benson County
Touchdown point
47.980, -99.550
Lift-off point
47.970, -99.530
Record number
1094

The warnings

12 minutes of warning. NWS FGF issued a tornado warning for this county at 23:06 UTC, 12 minutes before the tornado touched down, in force until 23:45 UTC.

Issued (UTC)ExpiredProductOffice
22:53 UTC23:45 UTCSevere Thunderstorm WarningFGF
23:06 UTC23:45 UTCTornado WarningFGF
23:42 UTC00:30 UTCTornado WarningFGF

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 19:37 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.

Bismarck Municip, ND (KBIS), 12:00Z

11.3 hours before the tornado, 160 km from the path. August 8, 2001.

Skew-T log-pSkew-T log-p diagram, Bismarck Municip, ND at 12:00Z on 2001-08-08Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 311 joules per kilogram, CIN -573, lifted condensation level 1769 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, Bismarck Municip, ND at 12:00Z on 2001-08-08The 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 108 square meters per square second, 0 to 6 km bulk shear 41 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
311 J/kg
Mixed-layer CIN
-573 J/kg
Surface CAPE
203 J/kg
Mixed-layer LCL
1769 m above ground
0-6 km bulk shear
41 kt
0-1 km bulk shear
8 kt
0-1 km storm-relative helicity
108 m²/s²
0-3 km storm-relative helicity
222 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

Bismarck Municip, ND (KBIS), 00:00Z

0.7 hours after it, 160 km from the path. August 9, 2001.

Skew-T log-pSkew-T log-p diagram, Bismarck Municip, ND at 00:00Z on 2001-08-09Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 3840 joules per kilogram, CIN -20, lifted condensation level 1294 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, Bismarck Municip, ND at 00:00Z on 2001-08-09The 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 -51 square meters per square second, 0 to 6 km bulk shear 25 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
3840 J/kg
Mixed-layer CIN
-20 J/kg
Surface CAPE
6627 J/kg
Mixed-layer LCL
1294 m above ground
0-6 km bulk shear
25 kt
0-1 km bulk shear
13 kt
0-1 km storm-relative helicity
-51 m²/s²
0-3 km storm-relative helicity
-48 m²/s²
Significant tornado parameter
-0.3
Supercell composite
-3.7
0-3 km lapse rate
7.3 K/km

Open this sounding in Storm Lab

The surface observations

Devils_lake (DVL), 49 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
21:35 UTC8664.450° 4 kt1008.1
21:55 UTC8666.240° 4 kt1008.1
22:15 UTC8664.470° 6 kt1008.1
22:35 UTC84.264.490° 6 kt1007.5
22:55 UTC84.266.230° 8 kt1008.1
23:15 UTC80.669.850° 11 kt1008.5
23:35 UTC78.86820° 9 kt1009.8
23:55 UTC7764.4350° 37 kt431010.2VCTS
00:15 UTC66.262.650° 22 kt271010.2TS
00:35 UTC66.262.650° 13 kt1011.2VCTS
00:55 UTC66.262.620° 13 kt1010.2
01:15 UTC66.260.830° 12 kt1009.8

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

This ground now

The live radar over the trackEvery 2001 tornado in North DakotaEvery tornado in North Dakota since 1950Warnings in force in North Dakota nowThe forecast where you are

The other tornadoes of August 8, 2001

4 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
August 84:20 PM MDTF0Sanpete, UT2.020
August 86:15 PM CDTF2Benson, ND7.0250$50,000
August 810:05 PM CDTF1Polk, MN0.550$70,000
August 810:10 PM CDTF0Clearwater, MN0.525

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.