tornado alley
It matters what game you are playing. For example i play Wizard101 and so far the hardest boss to me is Jabberwock.
Tornadoes are not given names as hurricanes are. The most damaging tornado recorded so far was the Topeka, Kansas tornado of 1966.
The most recent tornado in the world is the outbreak (so far) is in the USA in most of May.
Albany
Albany, North Shore
Hardest material ever FOUND so far is still diamond because it's produced by nature. Nano-materials are proven to be harder than any diamond but since it's man made it can not be "found". It's engineered. So the question for this nano variants should be - how hard do you need it to be ?
The greatest number of tornadoes recorded so far from a single hurricane is 117.
This is largely subjective. In terms of physical and financial barriers the hardest thing is probably rebuilding after a tornado or dealing with injuries. From an emotional standpoint the hardest thing is probably recovering, identifying, and burying the dead.
Boxing, by far.
It depends on which tornado you are referring to. South Dakota has had many tornadoes. Most have not been killers but some have been. So far in 2010, however, the have been no tornado fatalities in South Dakota.
Both Oklahoma and Missouri suffered very destructive tornadoes in 2011. Missouri was hit the hardest because of the Joplin tornado but that state is not entirely in Tornado Alley. Overall, the worst tornado damage in 2011 was in Alabama, but that state is several hundred miles from Tornado Alley.