LR - you are assuming that God can prevent all disasters. It all depends on what you mean by "omnipotent". A few months ago, I started a thread on that topic, hoping for a serious discussion. I should have known that that was a vain hope, with the obsessively sarcastic atheists on here.
I certainly don't think God arranges nice weather for Church events, and neither does any sensible Christian, though I've heard that sort of childish nonsense from happy-clappys before now.