I took these on Sunday 6-17-2012 from the balcony of my apartment. It was interesting to watch how this cloud formation progressed into a storm cloud with lightning. The still shots are the pre-lightning photos.
Here is the video of the storm cloud with lightning crackling around the inside of the cloud. My apologies for the camera shaking in a couple of places, I couldn’t find my tripod.
Chasing The Moonlight 
It’s like nature was having a fireworks show just inside the cloud. That is so cool. The clouds looked so docile before the lightning.
You made my day since I am such a weather geek!