Tornadoes · United States · Illinois · 1973

F1 tornado, Monroe County, Illinois, May 7, 1973

This F1 tornado ran 2.3 miles across Monroe County on May 7, 1973, touching down at 7:15 PM CDT and reaching 300 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 mphthis tornado

    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
F1
Date
May 7, 1973
Touchdown
7:15 PM CDT (00:15 UTC)
Path length
2.3 miles (3.7 km)
Path width
300 yards (274 m)
Deaths
0
Injuries
0
Property damage
$5,000 to $50,000
County
Monroe County
Touchdown point
38.280, -90.020
Lift-off point
38.320, -90.000
Record number
317

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.

Salem-Leckrone, IL (KSLO), 00:00Z

0.3 hours before the tornado, 104 km from the path. May 8, 1973.

Skew-T log-pSkew-T log-p diagram, Salem-Leckrone, IL at 00:00Z on 1973-05-08Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 494 joules per kilogram, CIN -1, lifted condensation level 725 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, Salem-Leckrone, IL at 00:00Z on 1973-05-08The 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 298 square meters per square second, 0 to 6 km bulk shear 56 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
494 J/kg
Mixed-layer CIN
-1 J/kg
Surface CAPE
879 J/kg
Mixed-layer LCL
725 m above ground
0-6 km bulk shear
56 kt
0-1 km bulk shear
32 kt
0-1 km storm-relative helicity
298 m²/s²
0-3 km storm-relative helicity
344 m²/s²
Significant tornado parameter
0.7
Supercell composite
5.2
0-3 km lapse rate
6.9 K/km

Open this sounding in Storm Lab

Salem-Leckrone, IL (KSLO), 12:00Z

11.7 hours after it, 104 km from the path. May 8, 1973.

Skew-T log-pSkew-T log-p diagram, Salem-Leckrone, IL at 12:00Z on 1973-05-08Temperature 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 -10367, lifted condensation level 585 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, Salem-Leckrone, IL at 12:00Z on 1973-05-08The 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 21 square meters per square second, 0 to 6 km bulk shear 37 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
0 J/kg
Mixed-layer CIN
-10367 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
585 m above ground
0-6 km bulk shear
37 kt
0-1 km bulk shear
16 kt
0-1 km storm-relative helicity
21 m²/s²
0-3 km storm-relative helicity
40 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

This ground now

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

The other tornadoes of May 7, 1973

23 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
May 72:25 AM CDTF2Searcy, AR2.7150$50,000 to $500,000
May 72:50 AM CDTF2Webster Parish, LA0.5272$5,000 to $50,000
May 71:20 PM CDTF2Clay, MO0.520$5,000 to $50,000
May 72:40 PM CDTF1Marengo, AL1.0400$5,000 to $50,000
May 72:45 PM CDTF1Ozark, MO5.050$5,000 to $50,000
May 73:05 PM CDTF2Baxter, AR2.0100$5,000 to $50,000
May 73:25 PM CDTF2Howell, MO7.41001$5,000 to $50,000
May 75:05 PM CDTF2Madison, MO14.6100$50,000 to $500,000
May 75:45 PM CDTF0Polk, MO1.050$5,000 to $50,000
May 75:45 PM CDTF1Pike, MO1.050$500 to $5,000
May 75:50 PM CDTF3Butler, MO36.01007$50,000 to $500,000
May 76:10 PM CDTF2Saint Louis, MO0.550$5,000 to $50,000
May 76:15 PM CDTF1Perry, MO1.050$500 to $5,000
May 76:30 PM CDTF0Story, IA0.560
May 76:40 PM CDTF2Perry, IL0.110
May 77:30 PM CDTF1Jefferson, IL0.1103
May 77:40 PM CDTF1Marion, IL0.1101
May 77:45 PM CDTF2Poinsett, AR4.71002$5,000 to $50,000
May 77:50 PM CDTF0Black Hawk, IA0.550
May 78:20 PM CDTF1Wayne, IL0.110$5,000 to $50,000
May 78:25 PM CDTF0Cape Girardeau, MO0.327$50 to $500
May 79:30 PM CDTF2Stoddard, MO0.327$50 to $500
May 712:45 AM ESTF1Marion, IN2.520$50,000 to $500,000

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.