EF1 tornado, Cook and Lake counties, Illinois and Indiana, August 11, 2026

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, as surveyed

EF1, preliminary

Date

August 11, 2026

Touchdown

10:41 AM CDT (15:41 UTC)

Lifted

11:00 AM CDT (16:00 UTC)

On the ground

19 minutes

Path length

22.5 miles (36.2 km)

Path width

300 yards (274 m)

Deaths

0

Injuries

0

Counties

Cook and Lake counties

Touchdown point

41.574, -87.906

Lift-off point

41.578, -87.500

Highest wind the damage implies

105 mph

Surveyed by

NWS LOT

The office's name for it

Orland Park - Hammond

Survey last edited

August 20, 2026

Record number

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

The tornado began just east of the Will-Cook county line in the Brook Hill Subdivision and moved rapidly east and southeastward across southern portions of Orland Park and Tinley Park, resulting in considerable damage to trees and power lines. Some structural damage to several buildings was noted along 183rd St. in Tinley Park. The tornado then crossed Interstates 80 and 57 before moving across Country Club Hills, Flossmoor, and Glenwood, where the most substantial tree damage was noted with numerous large trees snapped or uprooted along the path. Some trees fell onto buildings and cars, causing significant damage. The tornado crossed the Calumet Expressway and moved east-northeastward across Lansing, where it continued to produce considerable tree damage. The tornado crossed the state line just north of Ridge Rd. and continued to produce considerable tree damage into Munster before turning north into Hammond and dissipating shortly after crossing I-80 just east of Calumet Ave.

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

436 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 115 mph.

• Industrial sign blown down to the east.
• Chicago Heights reports power lines downed onto road near Ashland Avenue and 16th Street.
• Photo shared via social media shows sections of north facing wall blown out or collapsed from second floor room. Large sections of siding removed from remainder of building. Exact damage indicator difficult to determine, and nearby damage appears less severe in photo. Wind speed very approximately estimated.
• City of Crown Point reports Delaware Parkway blocked due to downed tree branches.

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

31 minutes of warning. NWS LOT issued a tornado warning for this county at 15:10 UTC, 31 minutes before the tornado touched down, in force until 16:00 UTC.

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.

The Chicago radar (KLOT), 32 km away, was scanning. The volume nearest the touchdown began at 15:41 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.