F1 tornado, Merrillville, Indiana, August 25, 2001

1. F040 to 72 mph

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

2. F173 to 112 mphthis tornado

   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.

Rating

F1

Date

August 25, 2001

Touchdown

5:31 PM CDT (22:31 UTC)

Path length

4.5 miles (7.2 km)

Path width

150 yards (137 m)

Deaths

0

Injuries

2

Property damage

$100,000

County

Lake County

Touchdown point

41.480, -87.330

Lift-off point

41.530, -87.230

Record number

393

A tornado touched down in Merrillville just east of the intersection of Merrillville Road and 84th Street. There was spotty minor structural damage in an industrial park with some small trees broken or pushed over, damage to signs and a few broken windows. Many structures and trees in the path had no damage. Just west of I-65, parts of the roof and glass walls of a commercial building were damaged. East of I-65, just south of Route 30, there was more damage to signs. A semi was overturned. Two people were injured by broken glass at a restaurant in Hobart. Part of the roof and a section of a wall was blown out at a Kohl's department store. The tornado crossed Route 30 and caused minor structural damage, mostly to signs and glass, at a strip mall. Behind the shops, corn was flattened and trees were damaged. The tornado then moved into the Green Acres subdivision near Colorado Street and 78th Street. A garage collapsed and many large tree limbs were blown down through the neighborhood. The tornado then weakened. Only minor damage to a few tree limbs occurred around the 7600 block of Clay Street and just south and east of the intersection of Grand and 73rd. The average path width was 50 yards.

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

0 minutes of warning. NWS LOT issued a tornado warning for this county at 22:31 UTC, 0 minutes before the tornado touched down, in force until 23:15 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 Slight Risk. The outlook in force was issued at 22:03 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), 68 km away, was scanning. The volume nearest the touchdown began at 22:29 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 2001 tornado in IndianaEvery tornado in Indiana since 1950Warnings in force in Indiana nowThe forecast where you are

4 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.