ohh I wish my school had a meteorology class, sounds fun. I'd definelty recommend doing your project on ball lightning, it's a phenomenon that still isn't 100% understood, and you could probly find loads of information on it. Oh! or you could do it on "sprites" they are an extremely rare type of upward lightning that shoots UP from the top of thunderheads towards space.
http://www.nasa.gov/centers/goddard/images/content/116920main_yellow_sprites_lg.jpg
There's also a few other types of rare lightning that happen above the thunderstrorms, I can't remember the names of them, you'll have to look them up. hmm, how about fire tornadoes? In particularly big fires, and under the perfect conditions, the fire can form a huge tornado-like whirlwind. http://en.wikipedia.org/wiki/Fire_whirl
I can't think of anymore rigt now but there are certainly more. Just look up weather phenomena on google and you'll get loads of stuff. Pick something that interests you and have fun!