I Tried to get this working myself since I already have IT downloaded and it has a thunderstorm weather, but I just ended up scaring the heck out of myself by accidentally making my FH not work because I was messing around with the files xD. I got it working now though o3o
A Suggestion, Maybe you could try downloading Sanctum Of Eventide or Impressive World (Two IT servers I know of) and see what you can do with the thunderstorm weather in there.