EF1 tornado, Hermon to Rapatee, Illinois, June 18, 2021

1. EF065 to 85 mph

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

2. EF186 to 110 mphthis tornado

   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.

Rating

EF1

Date

June 18, 2021

Touchdown

11:50 AM CDT (16:50 UTC)

Lifted

12:05 PM CDT (17:05 UTC)

On the ground

15 minutes

Path length

10.3 miles (16.5 km)

Path width

250 yards (229 m)

Deaths

0

Injuries

0

Property damage

$150,000

Crop damage

$100,000

County

Knox County

Touchdown point

40.787, -90.338

Lift-off point

40.715, -90.167

Record number

2106181050-01

2 damage points were recorded along this path by NWS ILX, in the Damage Assessment Toolkit the survey teams carry. The highest wind the damage implies is 100 mph.

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

Waves of low pressure tracking along a nearly stationary frontal boundary draped across central Illinois triggered strong to severe thunderstorms from the evening of June 18th through the early morning of June 19th. One of the storms produced an EF-1 tornado east of Abingdon in Knox County. The tornado flattened crops and caused significant damage to a few outbuildings. South of the tornado track, estimated 70 to 90 mph straight line winds caused damage in London Mills, Fairview, and Canton in northern Fulton County. As the storms continued eastward, numerous reports of wind damage were received across southern Peoria County into portions of Tazewell and McLean counties.

A tornado touched down 3.5 miles east-southeast of Abingdon at 11:50 PM CDT. The tornado tracked southeastward, flattening crops and knocking down numerous trees along its path. Significant damage occurred to several farm outbuildings along County Road 850 East north of County Highway 39, with debris being strewn southeastward for over a half mile. The tornado lifted about 0.5 miles west of Rapatee just north of the Fulton County line at 12:05 AM CDT.

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

No tornado warning for this county appears in the archive as in force at the moment the tornado touched down. One was issued for the county at another hour that day.

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 Storm Prediction Center had this point in a Enhanced Risk, with a 0.02 chance of a tornado within 25 miles. The outlook in force was issued at 16:37 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 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.

Galesburg (GBG), 26 km from the path, in the two hours either side.

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

The Quad Cities radar (KDVN), 100 km away, was scanning. The volume nearest the touchdown began at 16:49 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.

The live radar over the trackEvery 2021 tornado in IllinoisEvery tornado in Illinois since 1950Warnings in force in Illinois nowThe forecast where you are

7 more were confirmed in the United States that day.

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.

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.