Tornadoes · United States · Iowa · 1988

F0 tornado, Johnson County, Iowa, May 8, 1988

This F0 tornado ran 1.0 miles across Johnson County on May 8, 1988, touching down at 3:00 PM CDT and reaching 20 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
May 8, 1988
Touchdown
3:00 PM CDT (20:00 UTC)
Path length
1.0 miles (1.6 km)
Path width
20 yards (18 m)
Deaths
0
Injuries
0
Property damage
$500 to $5,000
County
Johnson County
Touchdown point
41.700, -91.500
Record number
134

The warnings

25 minutes of warning. NWS DMX issued a tornado warning for this county at 19:35 UTC, 25 minutes before the tornado touched down, in force until 20:15 UTC.

Issued (UTC)ExpiredProductOffice
19:35 UTC20:15 UTCTornado WarningDMX

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 Slight Risk. The outlook in force was issued at 06:40 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.

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

8.0 hours before the tornado, 196 km from the path. May 8, 1988.

Skew-T log-pSkew-T log-p diagram, Peoria Regional, IL at 12:00Z on 1988-05-08Temperature 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 -7438, lifted condensation level 1404 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 1988-05-08The 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 194 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
-7438 J/kg
Surface CAPE
0 J/kg
Mixed-layer LCL
1404 m above ground
0-6 km bulk shear
49 kt
0-1 km bulk shear
24 kt
0-1 km storm-relative helicity
194 m²/s²
0-3 km storm-relative helicity
203 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.1
0-3 km lapse rate
5.3 K/km

Open this sounding in Storm Lab

This ground now

The live radar over the trackEvery 1988 tornado in IowaEvery tornado in Iowa since 1950Warnings in force in Iowa nowThe forecast where you are

The other tornadoes of May 8, 1988

56 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
May 811:56 AM CDTF1Warren, IA11.030$50,000 to $500,000
May 81:10 PM CDTF1Wayne, IA2.030$50,000 to $500,000
May 81:25 PM CDTF2Wayne, IA47.043$50,000 to $500,000
May 81:47 PM CDTF2Davis, IA71.060$5 million to $50 million
May 81:58 PM CDTF2Poweshiek, IA59.060$500,000 to $5 million
May 82:06 PM CDTF1Black Hawk, IA2.020$50,000 to $500,000
May 82:06 PM CDTF1Mahaska, IA6.040$50,000 to $500,000
May 82:15 PM CDTF1Bremer, IA1.533$50,000 to $500,000
May 82:16 PM CDTF2Keokuk, IA36.060$50,000 to $500,000
May 83:10 PM CDTF1Muscatine, IA1.540$50,000 to $500,000
May 83:15 PM CDTF0Delaware, IA0.520$5,000 to $50,000
May 83:15 PM CDTF1Jones, IA10.040$50,000 to $500,000
May 83:15 PM CDTF0Jones, IA1.020$5,000 to $50,000
May 83:20 PM CDTF1Des Moines, IA1.030$50,000 to $500,000
May 83:22 PM CDTF0Delaware, IA0.520$5,000 to $50,000
May 83:30 PM CDTF2Monroe, WI27.0800$50,000 to $500,000
May 83:35 PM CDTF0Scott, IA1.020$5,000 to $50,000
May 83:36 PM CDTF1Dubuque, IA11.043$500,000 to $5 million
May 83:37 PM CDTF2Cedar, IA7.090$500,000 to $5 million
May 83:40 PM CDTF0Scott, IA1.020$5,000 to $50,000
May 83:43 PM CDTF3Scott, IA32.0150$5 million to $50 million
May 83:46 PM CDTF0Dubuque, IA0.520$5,000 to $50,000
May 83:48 PM CDTF1Grant, WI0.520$5,000 to $50,000
May 83:52 PM CDTF1Grant, WI1.530
May 83:54 PM CDTF1Grant, WI10.040
May 83:55 PM CDTF2Grant, WI10.040$50,000 to $500,000
May 84:00 PM CDTF1Grant, WI0.533$50 to $500
May 84:00 PM CDTF3Lafayette, WI16.0123$50,000 to $500,000
May 84:10 PM CDTF1Lafayette, WI9.0100$50,000 to $500,000
May 84:15 PM CDTF1Whiteside, IL0.310$5,000 to $50,000
May 84:15 PM CDTF2Grant, WI7.5200$50,000 to $500,000
May 84:15 PM CDTF1Grant, WI1.230
May 84:30 PM CDTF1Ogle, IL0.250$5,000 to $50,000
May 84:30 PM CDTF2Richland, WI20.0150$50,000 to $500,000
May 84:40 PM CDTF1Jackson, IL0.213$500 to $5,000
May 84:45 PM CDTF1Iowa, WI0.820$500 to $5,000
May 84:56 PM CDTF2Dane, WI7.01001$5,000 to $50,000
May 85:08 PM CDTF1Juneau, WI5.0731$500 to $5,000
May 85:15 PM CDTF1Columbia, WI2.073$50,000 to $500,000
May 85:15 PM CDTF1Juneau, WI0.720$500 to $5,000
May 85:20 PM CDTF0Lee, IL0.113$5,000 to $50,000
May 85:30 PM CDTF2Rock, WI27.0173$50,000 to $500,000
May 85:40 PM CDTF1Columbia, WI5.073$500 to $5,000
May 85:40 PM CDTF1Marquette, WI1.140$500 to $5,000
May 86:00 PM CDTF1Grundy, IL1.010$50,000 to $500,000
May 86:06 PM CDTF1Waushara, WI5.0100$50,000 to $500,000
May 86:10 PM CDTF2Marathon, WI13.02502$500,000 to $5 million
May 86:12 PM CDTF0Portage, WI1.020$500 to $5,000
May 86:15 PM CDTF0Dodge, WI0.550$500 to $5,000
May 86:18 PM CDTF2Sangamon, IL0.150$50,000 to $500,000
May 86:20 PM CDTF1LaSalle, IL0.5502$50,000 to $500,000
May 86:52 PM CDTF0Waukesha, WI0.120
May 87:00 PM CDTF1Will, IL18.0601$50,000 to $500,000
May 87:00 PM CDTF1Will, IL2.0403$50,000 to $500,000
May 87:45 PM CDTF0Vermilion, IL0.550$5,000 to $50,000
May 87:56 PM CDTF1Clark, AR0.230$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.