Elsa and Anna Are Back in 'Frozen 2'

I was never the biggest fan of Frozen, so I’ll just let others be psyched for this teaser. I thought it was alright, but no more than that. Be honest, the songs do not compare to anything that came out of the Ashman/Menken renaissance canon. They just don’t. Objectively. Anyway, why is Elsa having trouble getting over a wave of water? I will assume her powers are debilitated somehow. I’m sure November can’t come fast enough for a lot of people (but not me- I like Zootopia much better and would prefer a sequel to that).