Tornadoes · United States · Minnesota · 1973

F0 tornado, Waseca County, Minnesota, June 18, 1973

This F0 tornado ran 1.5 miles across Waseca County on June 18, 1973, touching down at 7:35 AM CDT and reaching 50 yards wide. It killed nobody, and did $500 to $5,000 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
June 18, 1973
Touchdown
7:35 AM CDT (12:35 UTC)
Path length
1.5 miles (2.4 km)
Path width
50 yards (46 m)
Deaths
0
Injuries
0
Property damage
$500 to $5,000
County
Waseca County
Touchdown point
43.930, -93.680
Record number
658

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.

Minneapolis, MN (KSTC), 12:00Z

0.6 hours before the tornado, 102 km from the path. June 18, 1973.

Skew-T log-pSkew-T log-p diagram, Minneapolis, MN at 12:00Z on 1973-06-18Temperature 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 -9192, lifted condensation level 1437 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, Minneapolis, MN at 12:00Z on 1973-06-18The 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 138 square meters per square second, 0 to 6 km bulk shear 37 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
-9192 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
1437 m above ground
0-6 km bulk shear
37 kt
0-1 km bulk shear
18 kt
0-1 km storm-relative helicity
138 m²/s²
0-3 km storm-relative helicity
263 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

Minneapolis, MN (KSTC), 00:00Z

11.4 hours after it, 102 km from the path. June 19, 1973.

Skew-T log-pSkew-T log-p diagram, Minneapolis, MN at 00:00Z on 1973-06-19Temperature 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 -11234, lifted condensation level 1736 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, Minneapolis, MN at 00:00Z on 1973-06-19The 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 29 square meters per square second, 0 to 6 km bulk shear 49 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
-11234 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
1736 m above ground
0-6 km bulk shear
49 kt
0-1 km bulk shear
7 kt
0-1 km storm-relative helicity
29 m²/s²
0-3 km storm-relative helicity
179 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
6.7 K/km

Open this sounding in Storm Lab

The surface observations

Mankato (MKT), 38 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
11:00 UTC63.8661290° 20 kt1004.1TSRA
11:50 UTC616110° 5 kt1004.7

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

This ground now

The live radar over the trackEvery 1973 tornado in MinnesotaEvery tornado in Minnesota since 1950Warnings in force in Minnesota nowThe forecast where you are

The other tornadoes of June 18, 1973

18 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
June 183:30 AM CDTF2Pierce, NE16.210$50,000 to $500,000
June 184:40 AM CDTF2Woodbury, IA2.0400210$50,000 to $500,000
June 184:46 AM CDTF2Woodbury, IA1.03005$50,000 to $500,000
June 188:40 AM CDTF1Freeborn, MN3.660$50,000 to $500,000
June 1812:00 PM CDTF1Marathon, WI2.0200$5,000 to $50,000
June 181:00 PM CDTF0Fulton, IL0.110
June 181:15 PM CDTF0Henry, IL0.110
June 183:10 PM CDTF0Woodford, IL0.110
June 185:30 PM CDTF3Osage, OK2.540$50,000 to $500,000
June 185:45 PM CDTF3Caddo, OK16.8133$50,000 to $500,000
June 186:00 PM CDTF2Kiowa, OK0.583$50 to $500
June 186:50 PM CDTF2Tillman, OK0.5100under $50
June 186:50 PM CDTF1Tillman, OK0.540under $50
June 187:00 PM CDTF2Caddo, OK0.567$50,000 to $500,000
June 187:15 PM CDTF3Tillman, OK3.35029$50,000 to $500,000
June 187:25 PM CDTF0Tillman, OK0.21329$500,000 to $5 million
June 188:00 PM CDTF1Grady, OK3.8501$500 to $5,000
June 189:00 PM CDTF1Washington, IL0.110

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.