I am intrigued. Complicated? yes. Impossible, I hope not. Try imagining wind as an actor and apply AI. In this way you could cause the actor to respond to different situations (pressure, obstacles, temperature, other weather actors, etc.) You could really get as complicated as you want. Then simply setting a speed parameter to randomize according to something silly like pawn position might be interesting.
To actually use a random generator might also work. Think procedural algorithm. Then a get Vector or float function. Of course again the numbers will not be truly random but what would be the limit of range?
And the number of particle animations and or physics associated with events can be made and mixed for the illusion of variation.
Sorry if this is all gibberish. I wish I had thought of it.