Tornadoes · United States · Illinois · 2018

EF0 tornado, Clarksville, Illinois, June 21, 2018

This EF0 tornado ran 0.2 miles across McLean County on June 21, 2018, touching down at 3:02 PM CDT and reaching 20 yards wide. It killed nobody.

The rating scale

Tracks are drawn in the color of the rating. The Enhanced Fujita scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.

  1. EF065 to 85 mphthis tornado

    Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

  2. EF186 to 110 mph

    Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

  3. EF2111 to 135 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. EF3136 to 165 mph

    Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.

  5. EF4166 to 200 mph

    Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

  6. EF5over 200 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
EF0
Date
June 21, 2018
Touchdown
3:02 PM CDT (20:02 UTC)
Lifted
3:03 PM CDT (20:03 UTC)
On the ground
1 minutes
Path length
0.2 miles (0.3 km)
Path width
20 yards (18 m)
Deaths
0
Injuries
0
County
McLean County
Touchdown point
40.670, -88.930
Lift-off point
40.668, -88.928
Record number
1806211402-01

The damage survey

2 damage points were recorded along this path by NWS ILX, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF0. The highest wind the damage implies is 70 mph.

  • Storm chaser reported landspout tornado

Survey points are preliminary and are the raw material the published rating was built from. Source: NWS Damage Assessment Toolkit.

What the Weather Service recorded

An unseasonably deep upper-level low slowly meandered eastward into Illinois on June 21st. Scattered thunderstorms developed beneath this feature during the afternoon, with many of the cells producing funnel clouds. One brief tornado was reported in a field about 5 miles southwest of Gridley in northern McLean County. Slow-moving storms dropped locally heavy rainfall across portions of Woodford County, causing flash flooding from Eureka to Washburn.

A tornado briefly touched down in an open field about 5 miles southwest of Gridley at 3:02PM CDT. The tornado quickly dissipated about one minute later with no damage being observed.

From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.

The warnings

No tornado warning for this county appears in the archive as in force at the moment the tornado touched down.

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 Marginal Risk, with a 0.02 chance of a tornado within 25 miles. The outlook in force was issued at 19:56 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.

Lincoln, IL (KILX), 12:00Z

8.0 hours before the tornado, 64 km from the path. June 21, 2018.

Skew-T log-pSkew-T log-p diagram, Lincoln, IL at 12:00Z on 2018-06-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 291 joules per kilogram, CIN -9, lifted condensation level 496 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, Lincoln, IL at 12:00Z on 2018-06-21The 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 41 square meters per square second, 0 to 6 km bulk shear 18 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
291 J/kg
Mixed-layer CIN
-9 J/kg
Surface CAPE
1254 J/kg
Mixed-layer LCL
496 m above ground
0-6 km bulk shear
18 kt
0-1 km bulk shear
10 kt
0-1 km storm-relative helicity
41 m²/s²
0-3 km storm-relative helicity
47 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.5
0-3 km lapse rate
5.3 K/km

Open this sounding in Storm Lab

Lincoln, IL (KILX), 00:00Z

4.0 hours after it, 64 km from the path. June 22, 2018.

Skew-T log-pSkew-T log-p diagram, Lincoln, IL at 00:00Z on 2018-06-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel lifted from the surface. Mixed-layer CAPE 544 joules per kilogram, CIN -12, lifted condensation level 791 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, Lincoln, IL at 00:00Z on 2018-06-22The 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 -27 square meters per square second, 0 to 6 km bulk shear 22 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
544 J/kg
Mixed-layer CIN
-12 J/kg
Surface CAPE
1106 J/kg
Mixed-layer LCL
791 m above ground
0-6 km bulk shear
22 kt
0-1 km bulk shear
5 kt
0-1 km storm-relative helicity
-27 m²/s²
0-3 km storm-relative helicity
31 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.0
0-3 km lapse rate
6.5 K/km

Open this sounding in Storm Lab

The radar

The Lincoln radar (KILX), 67 km away, was scanning. The volume nearest the touchdown began at 20:01 UTC.

Open the radar archive at this moment, over the track

Reflectivity and velocity, decoded from the Level II archive in the browser. Volumes take a few seconds to open the first time.

What was reported nearby

Local storm reports within 60 km of the path, in the three hours either side.

Time (UTC)ReportWhereCountyRemark
20:02 UTCTORNADO5 Ssw GridleyMclean, ILLATE REPORT FROM THURSDAY JUNE 21. EF-0 TORNADO, BRIEF TOUCHDOWN IN A FIELD.
20:30 UTCHEAVY RAIN 1.7NormalMclean, ILRAINFALL FROM AFTERNOON THUNDERSTORM.
21:10 UTCFLASH FLOOD5 Nne MetamoraWoodford, ILREPORTS OF FLOODED ROADWAYS FROM NORTH OF METAMORA TO LOW POINT.
21:10 UTCFLASH FLOODLow PointWoodford, ILREPORTS OF FLASH FLOODING THROUGHOUT WESTERN PORTIONS OF THE COUNTY.
21:15 UTCFLASH FLOODMetamoraWoodford, ILREPORTS OF STREETS FLOODED. TIME ESTIMATED BY RADAR.
21:15 UTCFLASH FLOODWashburnWoodford, ILREPORTS OF STREETS FLOODED. TIME ESTIMATED BY RADAR.
21:30 UTCFLASH FLOODSpring BayWoodford, ILREPORTS OF STREETS FLOODED. TIME ESTIMATED BY RADAR.
21:45 UTCFLASH FLOODVarnaMarshall, ILREPORTS OF NUMEROUS STREETS AND ROADS FLOODED THROUGHOUT THE CENTRAL AND EAST CENTRAL PORTIONS OF THE COUNTY. TIME ESTIMATED BY RADAR.
22:15 UTCHEAVY RAIN 4.863 W CullomLivingston, ILRAINFALL FOR PREVIOUS 24 HOURS. RELAYED BY WGN/CLTV.
23:00 UTCHEAVY RAIN 1.372 Nnw ShirleyMclean, IL1 HOUR RAINFALL AMOUNT ENDING JUST BEFORE 6 PM.

From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.

This ground now

The live radar over the trackEvery 2018 tornado in IllinoisEvery tornado in Illinois since 1950Warnings in force in Illinois nowThe forecast where you are

The other tornadoes of June 21, 2018

2 more were confirmed in the United States that day.

DateTimeRatingWherePath (mi)Width (yd)DeathsInjuriesDamage
June 211:15 PM MDTEF0Butte, ID5.180$3,000
June 216:18 PM CDTEF0Stoddard, MO4.5200

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.