Pure passion driven madness :)
I published this in 2013. So far this has been my biggest personal project ever - when I started I didn't know how to do most of this stuff. It's goal was to learn new things. Start with an idea, try to experience every possible "job" in such a project and finish it without a tight deadline (so I could learn, try, retry, etc).
More info about the project, it's progress etc. is in a post on BlenderArtists forum:
Two of the shots got selected for Blender's demoreel for Siggraph 2013. Tornadoes are around 1:16 mark but I recommend watching the whole thing (scroll down the page for the embeded video).
The author of the band's logo is Michał "Left Hand of Doom" Bukowski. You can find him here: