EF0 tornado, Grundy County, Illinois, August 11, 2026

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.

Rating, as surveyed

EF0, preliminary

Date

August 11, 2026

Touchdown

10:23 AM CDT (15:23 UTC)

Lifted

10:25 AM CDT (15:25 UTC)

On the ground

2 minutes

Path length

2.2 miles (3.5 km)

Path width

150 yards (137 m)

Deaths

0

Injuries

0

County

Grundy County

Touchdown point

41.400, -88.421

Lift-off point

41.385, -88.385

Highest wind the damage implies

80 mph

Surveyed by

NWS LOT

The office's name for it

Morris

Survey last edited

August 18, 2026

Record number

None yet. SPC numbers 2026 in the spring of 2027.

This tornado appeared to begin near the intersection of State Route 47 and Granville Road, initially damaging crops in the fields to the southeast of this intersection. Eyewitnesses reported seeing this tornado track across I-80 before it impacted a trailer retailer along US Route 6, where numerous trailers were tossed or rolled and sections of roofing material were peeled off of the retailer's main office building. A semi truck was also blown into a ditch along Route 6, and power lines were downed at this location as well. Farther to the southeast, damage to several trees was noted near the Grundy County Rod and Gun Club, where the tornado appeared to dissipate.

Written by NWS LOT in the NWS Damage Assessment Toolkit. A survey is revised as better evidence arrives.

44 damage points were recorded along this path by NWS LOT, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EFU. The highest wind the damage implies is 96 mph.

• Southern extent of tree damage
• Video shared to social media shows at least 5 tree uprooted, generally to the ESE or E, along Park Street near Wilmington Dam. Fence near dam blown down from west to east.
• Roofing material from building to the west blown into this building near S 1st street.
• A large portion of roofing was ripped off of an automotive repair shop. Pieces of rafter were thrown eastward into neighboring office buildings causing additional damage to roofing and siding.

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

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.

The county was under a severe thunderstorm watch, issued at 12:39 UTC and running to 16:38 UTC.

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 12:26 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.

Morris-Washburn (C09), 4 km from the path, in the two hours either side.

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

The Chicago radar (KLOT), 35 km away, was scanning. The volume nearest the touchdown began at 15:20 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.

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

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

The live radar over the trackEvery 2026 tornado in IllinoisEvery tornado in Illinois since 1950Warnings in force in Illinois nowThe forecast where you are

28 more have been surveyed in the United States that day, so far.

Ratings are the survey's, read off the damage rather than measured; the rating scale is above. A survey can be revised, so the rating, the path and the casualties can all still change.

NWS Damage Assessment Toolkit, the record the survey teams file from the damage, and NOAA Storm Prediction Center storm reports. Neither is the official database for 2026, which SPC publishes in the spring of 2027.