Tornadoes · United States · Wisconsin · 1974

F2 tornado, Marathon County, Wisconsin, April 12, 1974

This F2 tornado ran 0.1 miles across Marathon County on April 12, 1974, touching down at 3:05 PM CDT and reaching 150 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 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
April 12, 1974
Touchdown
3:05 PM CDT (20:05 UTC)
Path length
0.1 miles (0.2 km)
Path width
150 yards (137 m)
Deaths
0
Injuries
0
Property damage
$5,000 to $50,000
County
Marathon County
Touchdown point
45.030, -90.170
Lift-off point
45.070, -90.150
Record number
271

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.

Green Bay/Straub, WI (KGRB), 12:00Z

8.1 hours before the tornado, 175 km from the path. April 12, 1974.

Skew-T log-pSkew-T log-p diagram, Green Bay/Straub, WI at 12:00Z on 1974-04-12Temperature 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 -11122, lifted condensation level 524 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, Green Bay/Straub, WI at 12:00Z on 1974-04-12The 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 153 square meters per square second, 0 to 6 km bulk shear 56 knots.1939587897117136156Sfc1 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
-11122 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
524 m above ground
0-6 km bulk shear
56 kt
0-1 km bulk shear
33 kt
0-1 km storm-relative helicity
153 m²/s²
0-3 km storm-relative helicity
232 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
3.5 K/km

Open this sounding in Storm Lab

Green Bay/Straub, WI (KGRB), 00:00Z

3.9 hours after it, 175 km from the path. April 13, 1974.

Skew-T log-pSkew-T log-p diagram, Green Bay/Straub, WI at 00:00Z on 1974-04-13Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 16 joules per kilogram, CIN -10, lifted condensation level 1518 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, Green Bay/Straub, WI at 00:00Z on 1974-04-13The 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 30 square meters per square second, 0 to 6 km bulk shear 40 knots.1939587897Sfc1 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
16 J/kg
Mixed-layer CIN
-10 J/kg
Surface CAPE
180 J/kg
Mixed-layer LCL
1518 m above ground
0-6 km bulk shear
40 kt
0-1 km bulk shear
22 kt
0-1 km storm-relative helicity
30 m²/s²
0-3 km storm-relative helicity
31 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
7.0 K/km

Open this sounding in Storm Lab

This ground now

The live radar over the trackEvery 1974 tornado in WisconsinEvery tornado in Wisconsin since 1950Warnings in force in Wisconsin nowThe forecast where you are

The other tornadoes of April 12, 1974

9 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
April 122:45 AM CDTF1Rapides Parish, LA5.61503$5,000 to $50,000
April 123:30 AM CDTF2Grenada, MS0.110$5,000 to $50,000
April 123:15 PM CDTF2Shawano, WI10.71501$50,000 to $500,000
April 128:55 PM EDTF2Ogemaw, MI0.8100$500 to $5,000
April 129:20 PM EDTF1Kalamazoo, MI0.210$50 to $500
April 129:05 PM CDTF2Champaign, IL12.520$50,000 to $500,000
April 129:28 PM ESTF1Saint Joseph, IN0.110
April 1210:05 PM CDTF0Tangipahoa Parish, LA0.110
April 1210:30 PM CDTF0Assumption Parish, LA4.5172$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.