I think marhawkman has a point, in that it comes out of nowhere and any bits of continuity relating to this are just little nuggets that most people forgot about and don't really matter. Especially since Storm also changed her hair, which is weird unless she's sporting an unstable molecule wig.
Though personally, I'm more than fine with the transformation here. I can do without an explanation since it's not something that impacts the story in any tangible way. It's a nice way to convey Storm's character development and growth, and it's a huge upgrade over her old look. I'm fine with these little breaks in reality to visually convey something, because it enhances the point the story is trying to make.
Nevermind, ignore what I said. Clothing is a type of weather.