I've located some radar photos that I'd like to share from the outbreak. These come from two Monthly Weather Review publications. I've noted the approximate location of hook echoes or the actual tornado for these (in the text below). The radar operator changes the display mode from logarithmic (six level contoured) to linear (non contoured).
Some Synoptic Aspects and Dynamic Features of Vortices Associated with the Tornado Outbreak of 3 April 1974
E. Agee, C. Church, C. Morris, and J. Snow
Monthly Weather Review
1917Z (Fig. A)
Cell A: just east of Martinsville, IN
Cell B: 20 nm southwest of Seymour, IN
Cell C: no discernable hook on 125 nm range
http://img.photobucket.com/albums/v118/hoo...74/CVG1917Z.jpg
1947Z (Fig. B)
Cell A: 10 nm southeast of Indianapolis, or 8 nm southwest of Greenfield, IN
Cell B: 5 nm southeast of Columbus, IN, or 10 nm northeast of Seymour, IN
Cell C: no discernable hook on 125 nm range
http://img.photobucket.com/albums/v118/hoo...74/CVG1947Z.jpg
2001Z (Fig. C)
Cell A: near Greenfield, IN
Cell B: 10 nm northeast of Seymour, IN, or 15 nm southwest of Greensburg, IN
Cell C: near Depauw, IN
Xenia Cell: Butler/Warren Counties of Ohio, or 25-30 nm northeast of Cincinnati, OH
http://img.photobucket.com/albums/v118/hoo...74/CVG2001Z.jpg
2019Z (Fig. D)
Cell A: near Kennard, IN
Cell B: just south of Greensburg, IN
Cell C: near New Providence, IN, or 18 nm southwest of Scottsburg, IN
Xenia Cell: over Warren County, OH, or 30 nm northeast of Cincinnati, OH
http://img.photobucket.com/albums/v118/hoo...74/CVG2019Z.jpg
2053Z (Fig. E)
Cell A: northeast of Parker, IN (cell dissipating)
Cell B: 5 nm north of Brookville, IN
Cell C: near Madison, IN
Xenia Cell: about 5 nm northeast of Xenia, OH
Unlabeled Supercell NE of CVG: hook over southeast Hamilton County, OH (produced F1 in Pickaway Co, OH)
Unlabeled Supercell southwest of Cell C: over Meade County, KY, or 30 nm southwest of Louisville, KY (Brandenburg/Louisville tornadoes)
http://img.photobucket.com/albums/v118/hoo...74/CVG2053Z.jpg
2103Z: (Fig. F)
Cell A: dissipating
Cell B: dissipating
Cell C: western Switzerland County, IN, or 40 nm southwest of Cincinnati, OH
Xenia Cell: about 10 nm southwest of London, OH, or 30 nm west-southwest of Columbus, OH
Unlabeled Supercell NE of CVG: 25 nm NE of Cincinnati, OH (produced F1 in Pickaway Co, OH)
Unlabeled Supercell southwest of Cell C: between Irvington and Brandenburg, KY
http://img.photobucket.com/albums/v118/hoo...74/CVG2103Z.jpg
Multiple Vortex Features in the Tornado Cyclone and Occurence of Tornado Families
E. M. Agee, J. T. Snow and P. R. Clare
Monthly Weather Review
Fig. 9
Storm A: tornado near Monticello, IN
http://img.photobucket.com/albums/v118/hoo...locell2215Z.jpg
Fig. 10
Storm B: 8 nm southeast of Indianapolis, IN
Storm C: 7 nm west-northwest of Seymour, IN
Storm D: tornado estimated 14 nm southwest of Depauw, IN
http://img.photobucket.com/albums/v118/hoo...Gradar1940Z.jpg
Fig. 11
Storm C: tornado near Hamburg, IN (last tornado from that cell)
Storm D: hook echo 8 nm southwest of Madison, IN
http://img.photobucket.com/albums/v118/hoo...ar50nm2047Z.jpg
On The Reliability of Hook Echoes as Tornado Indicators
Gregory S. Forbes (1981)
Forbes studied radar photos from the super outbreak (125 nm range). Twenty-five well defined hook echoes were identified, with 84% of them tornadic, but these represented only 38% of the tornadic echoes. There were 34 non-hook echoes which were tornadic. Non-hook echoes included the "echo with an appendange on it's right rear flank" and the Line Echo Wave Pattern (LEWP). He terms the hook, appendage and LEWP as "distinctive echoes". Fifty-five distictive echoes were identified, with thirty-six of these (65%) tornadic. Nineteen non-distictive echoes produced tornadoes.
Just a brief overview of that paper. This one and the previous two are well worth the read.
