Most Calvinists are dour folks anyway.
I have been called many things, but I don’t believe I’ve ever been labeled as “dour,” ... until today.
Dour is not an attribute I would ever ascribe to John Piper. Perhaps you should look at just one of Piper's sermons - this is a man full of joy. Why? Because God has control of every situation ("don't waste your cancer!" was his catch phrase after coming down with prostate cancer).
The alternative view is that God was in some way surprised by the storms that went through the heartland. Perhaps he wanted to help - but he couldn't? Or worse yet he wouldn't?!
That is a pretty small god if you ask me...
Take an objective look at Calvinism, away from the influence of Arminian heresy, and you may see things differently.