Tornadoes · United States · Illinois · 1984

F0 tornado, Will County, Illinois, November 9, 1984

This F0 tornado ran 0.1 miles across Will County on November 9, 1984, touching down at 6:40 PM CST and reaching 10 yards wide. It killed nobody.

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
November 9, 1984
Touchdown
6:40 PM CST (00:40 UTC)
Path length
0.1 miles (0.2 km)
Path width
10 yards (9 m)
Deaths
0
Injuries
0
County
Will County
Touchdown point
41.430, -87.980
Record number
893

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.

Peoria Regional, IL (KPIA), 00:00Z

0.7 hours before the tornado, 160 km from the path. November 10, 1984.

Skew-T log-pSkew-T log-p diagram, Peoria Regional, IL at 00:00Z on 1984-11-10Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 490 joules per kilogram, CIN -49, lifted condensation level 1591 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, Peoria Regional, IL at 00:00Z on 1984-11-10The 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 62 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
490 J/kg
Mixed-layer CIN
-49 J/kg
Surface CAPE
1009 J/kg
Mixed-layer LCL
1591 m above ground
0-6 km bulk shear
62 kt
0-1 km bulk shear
28 kt
0-1 km storm-relative helicity
29 m²/s²
0-3 km storm-relative helicity
109 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1
0-3 km lapse rate
7.3 K/km

Open this sounding in Storm Lab

Peoria Regional, IL (KPIA), 12:00Z

11.3 hours after it, 160 km from the path. November 10, 1984.

Skew-T log-pSkew-T log-p diagram, Peoria Regional, IL at 12:00Z on 1984-11-10Temperature 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 -11878, lifted condensation level 1634 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, Peoria Regional, IL at 12:00Z on 1984-11-10The 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 81 square meters per square second, 0 to 6 km bulk shear 61 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
0 J/kg
Mixed-layer CIN
-11878 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
1634 m above ground
0-6 km bulk shear
61 kt
0-1 km bulk shear
12 kt
0-1 km storm-relative helicity
81 m²/s²
0-3 km storm-relative helicity
95 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0
0-3 km lapse rate
3.6 K/km

Open this sounding in Storm Lab

This ground now

The live radar over the trackEvery 1984 tornado in IllinoisEvery tornado in Illinois since 1950Warnings in force in Illinois nowThe forecast where you are

The other tornadoes of November 9, 1984

13 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
November 93:15 PM CSTF1Shannon, MO0.5100$5,000 to $50,000
November 94:00 PM CSTF1Sainte Genevieve, MO0.5100$500 to $5,000
November 94:05 PM CSTF1Wayne, MO8.0100$500 to $5,000
November 94:30 PM CSTF1Wayne, MO1.0100$5,000 to $50,000
November 94:45 PM CSTF2Bond, IL30.015011$500,000 to $5 million
November 95:10 PM CSTF0Jefferson, MO0.377
November 95:20 PM CSTF3Nevada, AR6.0880$5,000 to $50,000
November 95:32 PM CSTF1Cape Girardeau, MO1.0100$5,000 to $50,000
November 95:40 PM CSTF0Ripley, MO0.377
November 96:00 PM CSTF1Jackson, IL0.110
November 96:05 PM CSTF1Ripley, MO1.0100$50,000 to $500,000
November 96:15 PM CSTF2Washington, MO3.0340115$5 million to $50 million
November 99:47 PM CSTF0Jackson, 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.