What do tornadoes have to do with the water cycle?

Answer 1

They don't really have anything to do with it, other than often being associated with frontaly storm systems (which will usually cause a lot of rain).

Tornadoes occur in all weathers, from heavy rain to drought conditions (all a dust devil is is a mini tornado)

Answer 2

I would say that tornadoes have virtually nothing to do with the water cycle. The storms that generate them may have pretty high rain rates, but not necessarily anything higher than non-tornadic thunderstorms. Tornadoes are too localized to have any general effect. Hurricanes, on the other hand, can be large contributers to the water cycle...