F3 tornado, Florid, Illinois, April 20, 2004

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 mph

   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 mphthis tornado

   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

F3

Date

April 20, 2004

Touchdown

5:44 PM CDT (22:44 UTC)

Path length

15.8 miles (25.4 km)

Path width

880 yards (805 m)

Deaths

8

Injuries

12

Property damage

$8.0 million

Counties

Putnam and LaSalle counties

Touchdown point

41.250, -89.280

Lift-off point

41.330, -89.020

Record number

807

2 damage points were recorded along this path by NWS LOT, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF2. The highest wind the damage implies is 120 mph.

• Top story of 2 floor home destroyed.
• Multiple farm outbuildings significantly damaged. Collapsed walls on one building and another building rolled off foundation.

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

The low topped supercell that produced 2 earlier tornadoes in Stark and Marshall/Bureau counties continued to be a cyclic tornado producer. The deadliest and longest lived tornado started at 1644 CST, 0.7 miles North Northeast of Florid in Putnam County and moved northeast toward Granville. The long lived nature of the tornado was due to it riding along a warm front pushing through Putnam and La Salle counties. Satellite imagery indicated a strengthening mesocyclone at 1625 CST (2225 Z) with the formation of a new line of feeder clouds into the supercell, and KDVN 88D velocity data showed a strengthening TVS signature by 1635 CST (2235 Z). Witnesses reported a multiple vortex tornado just prior to its arrival in Granville. The tornado hit Granville at 1647-1648 CST which coincided with the failure of the main power feed into town. The town was bisected by the half mile wide tornado with 12 buildings destroyed, 45 with major damage, and 26 with minor damage (mainly residential). The Granville State National Bank lost its roof and Hopkins Elementary School lost the roof over the old gymnasium with damage in nearly all the classrooms. Significant damage also occurred to Granville Drugs, the only drug store in town. In a strange twist of irony, the town had finally recovered from a major fire 4 years earlier that decimated much of the business district. The tornado continued northeast out of Granville and crossed over into La Salle County (WFO LOT) at 1653 CST (2253 Z), 3.8 miles Northeast of Granville. The Granville/Utica tornado was the first significant test of a new statewide mutual aid response agreement. In Granville 5 people were injured by the tornado, including an eldery female who suffered a heart attack during the tornado and was eventually Life Flighted to a Peoria hospital. Injuries were low due to the 32 minutes of lead time before the tornado struck Granville. Damage in Granville is estimated to be at least $8 million with the school suffering at least $3.5 million in damage.

Rated very high end F2

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

29 minutes of warning. NWS DVN issued a tornado warning for this county at 22:15 UTC, 29 minutes before the tornado touched down, in force until 23:00 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 General Thunderstorms Risk. The outlook in force was issued at 19:58 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.

Peru (VYS), 7 km from the path, in the two hours either side.

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

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 2004 tornado in IllinoisEvery tornado in Illinois since 1950Warnings in force in Illinois nowThe forecast where you are

31 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.