Lyxen
Great Old One
Each phase involves each player rolling on the Random Storm Event Table. At phase #1 it's a d6 (1-6), then at phase #2 a d6+2 (3-8), then at phase #3 a d6+4 (5-10). You might want to add more options – for time's sake, I'm just giving you a baseline to design your own from.
I've always wondered what the point of having random events was. First, you need to design more interesting events than what will really happen. Second, you will end up throwing a majority of these interesting events down the drain. I can understand it from published adventures where they are used to show a panel of more or less interesting things that the DM might implement or not depending on the taste of the party, but when designing the adventure yourself, surely you can choose the ones that will play the best for your players rather than rely on chance ?
That being said, your examples are interesting, of course, it would be all the more a shame to discard nice ideas...