Tornadoes · United States · Indiana · 1975

F0 tornado, Carroll County, Indiana, August 11, 1975

This F0 tornado ran 2.0 miles across Carroll County on August 11, 1975, touching down at 4:43 PM EST and reaching 50 yards wide. It killed nobody, and did $5,000 to $50,000 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
August 11, 1975
Touchdown
4:43 PM EST (21:43 UTC)
Path length
2.0 miles (3.2 km)
Path width
50 yards (46 m)
Deaths
0
Injuries
0
Property damage
$5,000 to $50,000
County
Carroll County
Touchdown point
40.720, -86.750
Record number
769

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.

Dayton/James M C, OH (KDAY), 12:00Z

9.7 hours before the tornado, 235 km from the path. August 11, 1975.

Skew-T log-pSkew-T log-p diagram, Dayton/James M C, OH at 12:00Z on 1975-08-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 747 joules per kilogram, CIN -51, lifted condensation level 844 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, Dayton/James M C, OH at 12:00Z on 1975-08-11The 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 121 square meters per square second, 0 to 6 km bulk shear 23 knots.1939Sfc1 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
747 J/kg
Mixed-layer CIN
-51 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
844 m above ground
0-6 km bulk shear
23 kt
0-1 km bulk shear
23 kt
0-1 km storm-relative helicity
121 m²/s²
0-3 km storm-relative helicity
124 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
4.6 K/km

Open this sounding in Storm Lab

Dayton/James M C, OH (KDAY), 00:00Z

2.3 hours after it, 235 km from the path. August 12, 1975.

Skew-T log-pSkew-T log-p diagram, Dayton/James M C, OH at 00:00Z on 1975-08-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 155 joules per kilogram, CIN -86, lifted condensation level 1623 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, Dayton/James M C, OH at 00:00Z on 1975-08-12The 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 48 square meters per square second, 0 to 6 km bulk shear 14 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
155 J/kg
Mixed-layer CIN
-86 J/kg
Surface CAPE
1459 J/kg
Mixed-layer LCL
1623 m above ground
0-6 km bulk shear
14 kt
0-1 km bulk shear
9 kt
0-1 km storm-relative helicity
48 m²/s²
0-3 km storm-relative helicity
78 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
6.9 K/km

Open this sounding in Storm Lab

The surface observations

Lafayette (LAF), 37 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
20:00 UTC8873230° 10 kt1014.2DZ
21:00 UTC8673220° 10 kt1014.2DZ
22:00 UTC8574220° 9 kt1014.2DZ
22:55 UTC8269230° 4 kt1013.9

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

This ground now

The live radar over the trackEvery 1975 tornado in IndianaEvery tornado in Indiana since 1950Warnings in force in Indiana nowThe forecast where you are

The other tornadoes of August 11, 1975

3 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
August 115:00 AM CDTF0Cedar, NE0.110$500 to $5,000
August 117:00 PM MDTF0Adams, ND0.117
August 1110:00 PM EDTF1Saint Lucie, FL0.1301$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.