The last decade has been rather intriguing regarding severe weather, both locally and nationally. It's very difficult, however, to draw any type of conclusions because the dataset regarding severe weather is not only small but the degree of accuracy is even smaller. What we have seen this past decade is;
1. "Tornado Ally" has shifted a bit east...for so many years the Great Plains were considered the tornado home of the U.S. but last decade there has been a sharp increase just along/east of the Mississippi River to the Appalachian Mountains.
2. A decrease in strong/violent tornadoes (obviously there have been some monsters)
3. An increase in "out of season" tornadoes across the Northeast region and even nocturnal tornadoes...but thankfully the majority of these tornadoes have remained weak (of course we have some exceptions).
But if we continue to see these themes of higher dewpoint air and higher dewpoint air occurring earlier in the season and later in the season we will continue to see an increase in these "out of season" setups.