F0 tornado, Piasa to Gillespie, Illinois, April 2, 2006

1. F040 to 72 mphthis tornado

   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 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

F0

Date

April 2, 2006

Touchdown

5:21 PM CDT (22:21 UTC)

Path length

16.0 miles (25.7 km)

Path width

50 yards (46 m)

Deaths

0

Injuries

0

Counties

Madison and Macoupin counties

Touchdown point

38.950, -90.000

Lift-off point

39.070, -89.730

Record number

229

In Piasa a tornado struck around 515 pm CDT and damaged the roof and siding of numerous homes, snapped several trees and wooden power poles, and took large branches out of trees. Damage was intermittent along a path continuing two miles east of Piasa on Highway 16, where the tornado destroyed a barn near Beacon Road and collapsed a parking canopy at Shipman Elevator Company. A man approximately 1.5 miles north of this tornado witnessed sheet metal debris rotating in the air and dirt swirling on the ground. A woman driving on Highway 16 reported being pushed off the road by the tornado. Total track length of this F0 tornado was 2 miles with a maximum width of 30 yards.

Two miles northeast of Piasa along Little Flock Road another tornado struck around 515 pm CDT and damaged farm buildings and a grain bin. It then destroyed a mobile home after lifting and carrying it approximately 20 yards. This tornado was rated F0 with a track length of one-half mile and track width of 30 yards.

A small but rather long tornado first formed in Madison County just north of Dorsey. Trees were damaged and roof shingles were blown off a couple of homes. The tornado continued into Macoupin County.

The Madison County tornado that started near Dorsey crossed the Macoupin County line about 6 miles west southwest of Staunton. The tornado damaged trees, downed a few power lines, and blew off roof shingles near Staunton and Mt. Olive.

The line of thunderstorms that produced small tornadoes near Piasa produced a third tornado around 535 pm CDT. This tornado destroyed a mobile home two miles north of Gillespie on Highway 4 at Quarry Road. This tornado was rated F0 with a path length of one-tenth of a mile and a width of 20 yards.

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.

The county was under a tornado watch, issued at 21:17 UTC and running to 23:39 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 Moderate Risk, with a 0.10 chance of a tornado within 25 miles, in the hatched area where significant tornadoes were expected. The outlook in force was issued at 19:55 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.

Alton/St Louis R (ALN), 21 km from the path, in the two hours either side.

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

The St Louis radar (KLSX), 79 km away, was scanning. The volume nearest the touchdown began at 22:20 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 2006 tornado in IllinoisEvery tornado in Illinois since 1950Warnings in force in Illinois nowThe forecast where you are

66 more were confirmed in the United States that day.

All 67 of them

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.