Taken on our test server, this is an F3.

The server was setup using forge. Currently running the Tornado Mod, and Millinare.
I was playing with a few friends coop earlier today. We were building up millinare villages and having them fight each other. That is, if a F5 twister did not wreck everything first.

Has anyone used or seen the tornado mod on multiplayer, or even singleplayer before?
This is the mod link: http://www.coros.us/mods/tornadoes