Tornadoes · United States · Michigan · 1974

F3 tornado, Genesee County, Michigan, July 14, 1974

This F3 tornado ran 1.0 miles across Genesee County on July 14, 1974, touching down at 5:22 PM EDT and reaching 33 yards wide. It killed nobody, and did $50,000 to $500,000 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 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 mphthis tornado

    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
F3
Date
July 14, 1974
Touchdown
5:22 PM EDT (21:22 UTC)
Path length
1.0 miles (1.6 km)
Path width
33 yards (30 m)
Deaths
0
Injuries
0
Property damage
$50,000 to $500,000
County
Genesee County
Touchdown point
43.050, -83.550
Record number
722

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.

Detroit, MI (KFNT), 12:00Z

9.4 hours before the tornado, 38 km from the path. July 14, 1974.

Skew-T log-pSkew-T log-p diagram, Detroit, MI at 12:00Z on 1974-07-14Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 1542 joules per kilogram, CIN -163, lifted condensation level 1010 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, Detroit, MI at 12:00Z on 1974-07-14The 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 -10 square meters per square second, 0 to 6 km bulk shear 15 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
1542 J/kg
Mixed-layer CIN
-163 J/kg
Surface CAPE
161 J/kg
Mixed-layer LCL
1010 m above ground
0-6 km bulk shear
15 kt
0-1 km bulk shear
18 kt
0-1 km storm-relative helicity
-10 m²/s²
0-3 km storm-relative helicity
-6 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

Detroit, MI (KFNT), 00:00Z

2.6 hours after it, 38 km from the path. July 15, 1974.

Skew-T log-pSkew-T log-p diagram, Detroit, MI at 00:00Z on 1974-07-15Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 818 joules per kilogram, CIN -73, lifted condensation level 1508 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, Detroit, MI at 00:00Z on 1974-07-15The 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 137 square meters per square second, 0 to 6 km bulk shear 30 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
818 J/kg
Mixed-layer CIN
-73 J/kg
Surface CAPE
1152 J/kg
Mixed-layer LCL
1508 m above ground
0-6 km bulk shear
30 kt
0-1 km bulk shear
28 kt
0-1 km storm-relative helicity
137 m²/s²
0-3 km storm-relative helicity
152 m²/s²
Significant tornado parameter
0.2
Supercell composite
0.8
0-3 km lapse rate
6.3 K/km

Open this sounding in Storm Lab

The surface observations

Flint (FNT), 19 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
20:00 UTC8969270° 7 kt1009.5
21:00 UTC9066240° 15 kt1008.8TSRA
21:20 UTC350° 15 kt301010.5
22:00 UTC7668350° 8 kt1010.2
23:00 UTC826820° 5 kt1010.5

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

This ground now

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

The other tornadoes of July 14, 1974

10 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
July 142:15 AM EDTF1Delta, MI5.227$5,000 to $50,000
July 141:15 PM CDTF0Cook, IL0.110
July 143:00 PM EDTF1Mecosta, MI1.520$500 to $5,000
July 143:00 PM EDTF1Bay, MI0.110
July 145:00 PM EDTF1Macomb, MI0.110$50 to $500
July 145:08 PM EDTF2Wayne, MI1.527$50,000 to $500,000
July 145:20 PM EDTF1Macomb, MI0.313$500 to $5,000
July 145:23 PM EDTF1Oakland, MI0.110$5,000 to $50,000
July 144:30 PM CDTF2Harris, TX0.8880$500,000 to $5 million
July 146:10 PM CDTF1Bossier Parish, LA0.110$500 to $5,000

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.