chrisbray
EF4
ESRL 20th Century Reanalysis (great multi-purpose tool for historical weather analysis of many forms): http://www.esrl.noaa.gov/psd/data/20thC_Rean/
Jonathan Finch's (NWS DDC) site (has plenty of analysis of past tornado events): http://bangladeshtornadoes.org/
For the US Cases specifically: http://bangladeshtornadoes.org/UScases.html
Honest question - how the heck do you use the ESRL page? I can't figure it out.