I need a more positive synonym for the word "storm"?

In a speech I have written for my public speaking cl, my theme is the ripple effect, and how even the tiniest change in one drop of water can change a whole lake. I about comparing the world to a lake, etc. My last sentence is, "Let us stand for a greater plan, in which even the tiniest ripple can grow to become a storm." My teacher thinks this is a good final sentence, but wants me to use (instead of 'storm') a word that people think of more positively. Any suggestions?