Tornadoes · United States · Illinois · 1993

F0 tornado, McHenry County, Illinois, June 8, 1993

This F0 tornado ran 0.2 miles across McHenry County on June 8, 1993, touching down at 7:47 PM CDT and reaching 20 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
June 8, 1993
Touchdown
7:47 PM CDT (00:47 UTC)
Path length
0.2 miles (0.3 km)
Path width
20 yards (18 m)
Deaths
0
Injuries
0
County
McHenry County
Touchdown point
42.230, -88.330
Record number
484

The warnings

17 minutes of warning. NWS LOT issued a tornado warning for this county at 00:30 UTC, 17 minutes before the tornado touched down, in force until 01:00 UTC.

Issued (UTC)ExpiredProductOffice
00:30 UTC01:00 UTCTornado WarningLOT
01:00 UTC02:00 UTCSevere Thunderstorm WarningLOT

Every warning and watch covering the touchdown point that day, from the Iowa Environmental Mesonet's archive of National Weather Service products. Lead time is measured from the issue of the warning in force to the touchdown time in the database, both of which were recorded to the minute by different people.

The forecast that day

The Storm Prediction Center had this point in a High Risk. The outlook in force was issued at 06:00 UTC.

SPC's Day 1 convective outlook as it stood when the tornado began, read at the touchdown point. The same archive is on the radar archive.

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), 00:00Z

0.8 hours before the tornado, 251 km from the path. June 9, 1993.

Skew-T log-pSkew-T log-p diagram, Green Bay/Straub, WI at 00:00Z on 1993-06-09Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 4221 joules per kilogram, CIN -161, lifted condensation level 779 meters above ground. Wind barbs in knots down the right edge.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 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 1993-06-09The 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 -14 square meters per square second, 0 to 6 km bulk shear 47 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
4221 J/kg
Mixed-layer CIN
-161 J/kg
Surface CAPE
5728 J/kg
Mixed-layer LCL
779 m above ground
0-6 km bulk shear
47 kt
0-1 km bulk shear
7 kt
0-1 km storm-relative helicity
-14 m²/s²
0-3 km storm-relative helicity
151 m²/s²
Significant tornado parameter
-0.2
Supercell composite
-3.5
0-3 km lapse rate
5.0 K/km

Open this sounding in Storm Lab

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

11.2 hours after it, 251 km from the path. June 9, 1993.

Skew-T log-pSkew-T log-p diagram, Green Bay/Straub, WI at 12:00Z on 1993-06-09Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 20 joules per kilogram, CIN -40, lifted condensation level 897 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 12:00Z on 1993-06-09The 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 70 square meters per square second, 0 to 6 km bulk shear 39 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
20 J/kg
Mixed-layer CIN
-40 J/kg
Surface CAPE
244 J/kg
Mixed-layer LCL
897 m above ground
0-6 km bulk shear
39 kt
0-1 km bulk shear
22 kt
0-1 km storm-relative helicity
70 m²/s²
0-3 km storm-relative helicity
113 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.3
0-3 km lapse rate
5.7 K/km

Open this sounding in Storm Lab

The surface observations

Chicago/Dupage (DPA), 36 km from the path, in the two hours either side.

Time (UTC)Temp (°F)Dew point (°F)WindGust (kt)Pressure (mb)Weather
23:00 UTC8172.86190° 11 kt1001.7
00:00 UTC79.8867200° 12 kt1002
01:00 UTC7065210° 20 kt301002.7
02:00 UTC6863300° 8 kt1003.7

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

This ground now

The live radar over the trackEvery 1993 tornado in IllinoisEvery tornado in Illinois since 1950Warnings in force in Illinois nowThe forecast where you are

The other tornadoes of June 8, 1993

57 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
June 86:35 AM CDTF0Miller, MO0.450$500 to $5,000
June 810:08 AM CDTF0Love, OK1.540$5,000 to $50,000
June 810:45 AM CDTF0Boone, IA0.220$5,000 to $50,000
June 81:05 PM CDTF1Vernon, WI11.0100$50,000 to $500,000
June 81:08 PM CDTF1Winnebago, IA0.330$5,000 to $50,000
June 81:20 PM CDTF2Mitchell, IA6.0100$50,000 to $500,000
June 81:55 PM CDTF0Mower, MN0.110
June 81:55 PM CDTF0Mower, MN0.110
June 81:55 PM CDTF0Mower, MN0.110
June 82:07 PM CDTF0Fillmore, MN0.110
June 82:07 PM CDTF0Fillmore, MN0.110
June 82:28 PM CDTF0Olmsted, MN0.110
June 82:30 PM CDTF0Adams, WI1.573$500 to $5,000
June 83:01 PM CDTF1Itasca, MN0.510$500 to $5,000
June 83:08 PM CDTF0Olmsted, MN0.110
June 84:30 PM EDTF0Putnam, OH0.230$50,000 to $500,000
June 84:32 PM EDTF1Hancock, OH1.030$5,000 to $50,000
June 84:25 PM CDTF0Koochiching, MN0.110
June 84:48 PM CDTF0Adams, WI1.050
June 84:52 PM CDTF0Adams, WI1.573
June 85:06 PM CDTF1Marquette, WI10.0850$50,000 to $500,000
June 85:07 PM CDTF0Kay, OK0.120
June 86:10 PM EDTF1Cambria, PA1.0100$50,000 to $500,000
June 85:10 PM CDTF0Marquette, WI1.050$50 to $500
June 85:16 PM CDTF0Koochiching, MN0.110
June 85:20 PM CDTF0Kay, OK0.120
June 85:23 PM CDTF0Marquette, WI0.123$50 to $500
June 85:26 PM CDTF2Columbia, WI28.01,000$50,000 to $500,000
June 85:30 PM CDTF1Sangamon, IL5.0100
June 85:30 PM CDTF0Madison, IL0.430$5,000 to $50,000
June 85:30 PM CDTF0Adams, WI2.073
June 85:35 PM CDTF0Adams, WI0.523
June 85:35 PM CDTF3Kay, OK11.5150$50,000 to $500,000
June 85:37 PM CDTF0Green Lake, WI0.330
June 85:40 PM CDTF0Macon, IL3.023$50,000 to $500,000
June 86:45 PM EDTF1Fayette, PA3.02502$50,000 to $500,000
June 85:45 PM CDTF0Green Lake, WI4.050$50 to $500
June 86:15 PM CDTF0Kay, OK0.380
June 86:20 PM CDTF0Champaign, IL0.110
June 86:23 PM CDTF0Champaign, IL0.110
June 86:23 PM CDTF1Louisa, IA5.040$5,000 to $50,000
June 86:28 PM CDTF0Champaign, IL0.110
June 86:35 PM CDTF0Winnebago, WI0.123
June 86:38 PM ESTF0Tippecanoe, IN0.120
June 86:40 PM ESTF1Tippecanoe, IN10.060$5,000 to $50,000
June 86:40 PM ESTF1Marshall, IN19.073$50,000 to $500,000
June 87:01 PM CDTF0Vermilion, IL0.110
June 87:16 PM CDTF0Vermilion, IL0.110
June 87:20 PM ESTF0Kosciusko, IN0.110
June 87:35 PM CDTF0Washington, OK0.130
June 87:38 PM CDTF0Waushara, WI8.023$50 to $500
June 87:59 PM CDTF0Dane, WI4.050$50 to $500
June 88:15 PM CDTF0Waushara, WI12.033$500 to $5,000
June 88:35 PM CDTF0Waushara, WI6.023$500 to $5,000
June 810:10 PM CDTF0Fannin, TX0.110
June 810:20 PM CDTF0Green Lake, WI0.123
June 811:39 PM CDTF0Whiteside, IL1.030$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.