The Jarell Texas tornado was one of the most violent tornadic events of all time. Unknown to most, the supercells or rotating storms spawned 20 tornadoes on this particular outbreak which tracked southwest, since the storms backbuilt southwestwards. http://stormstalker.files.wordpress.com/2012/11/temple-sounding.gif
http://www.youtube.com/watch?v=yc1O1d_7HPU
The Jarell tornado was allocated an F5 rating. Since the tornado progressed at a slow rate, experts believe the slow movement contributed to the intensity of the tornado. Nothing was left standing in the estate that was impacted by the 3/4 mile wide tornado and unfortunately 27 rsidents were killed and only a few that were directly impacted only suffered injuries and survived. 
As can be seen from the sounding, extreme CAPE of nearly 7000J/kg was evident in this day making the instability extremely unstable! The southwest movement of the tornadic supercells made up for the relatively weaker wind shear providing potent conditions nestled along a boundary oriented southwest to northeast. http://extremeplanet.files.wordpress.com/2012/06/jarrell-f5-tornado-damage-junga.png 
http://www.youtube.com/watch?v=gHWO6stGaQ0