This evening (August 4th 2012) we had a thunderstorm in Ann Arbor. Just as the storm started, we experienced the loudest thunder we have ever heard. I have previously been in buildings during a lightning strike (about 20 feet from the strike), and the thunder tonight was far louder. Three or four super-loud thunderclaps happened between 9:30 and 10 pm, with a delay of between 3 and 10 seconds from the lightning to the arrival of the thunder (so it wasn't even near us). Karen and I could feel the percussive force from each thunderclap in our chests.
A quick web search suggested that many other people have recently experienced similar extreme lightning & thunder... Extreme lightning with super-loud thunder? What's going on?