[Unistorm 1.6] How to implement scripted weather

So I bought UniStorm 1.6 a few hours ago to test its potential and try to play around with it in order to learn how to implement its capabilities in my future creations, but I'm having troubles with one thing, despite it being a fantastic, well crafted, and more or less intuitive system (Though I would encourage the devs to be slightly more precise and exemplifying in the documentation :P)

How do I change the weather, not totally randomly, but according to certain events?

For instance, if I want to change the weather to "Rainy", when the player walks past a certain point, how could I implement that, or reference the core scripts to do so.

Thanks a lot in advance, I appreciate any help or clue given, and for those of you who haven't tried UniStorm, I'd suggest to go ahead and take a look :)

E.