The shout has to at-least work in-doors right? If not why bother spending souls for it, so I think it is just the shout that caused the rain falling through... It is a idea but saying that I am usually a Glass is Half-full kinda guy.
You have to understand that Storm Call is the 3 Tier of the Shout, the are 2 levels below that we don't know what they do.
LvL 3 of any Shout is like a God Power that kills everything in a 2 mile Radius, but LvLs 1 and 2 will probably be better suited for tight spaces.
Plus, the way Shouts seem to be structured is there's one for every situation, like Utilities.