Trying to connect any single weather event to climate change is silly.
Statistically, can we see evidence of changes in tornadic activity?
If yes, then we can intuite that global changes are happening.
If not, then the evidence doesn't support your theory.
This presents, at present, and interesting subject. There are great natural variations year to year in the strengths and number of extreme weather events. So the question is, are the events of the last decade within the range of natural variation? Right now, the answer is yes, barely.
The next question, is the increase in the number and strength great enough to suspect that this is more than just natural variation? Again, the answer is yes. But only barely.
OK, now we have established doubt on all sides, the third question is, is the increase in GHGs having any affect on climate and weather? The answer to that is an unequivocal 'YES'. From the Arctic and Alpine ice, we see the effects. From the timing of the movements of migrating animals and birds, to the upward movement of plants in alpine regions, we see the evidence of the effects of the warming of the globe.
Statistically, there is not unequivocal support for those that state what we are seeing is normal, nor for those that state that this is an effect of global warming. Given the other effects that we can definitely ascribe to the warming, I believe that by 2025, there will be enough extreme events to state unequivocally that warming is the cause of the increase.