Is she saying "naeth" in the slow version? To me it sounds like an n, not a w.
I think it's the transition from "hi'n" to "waeth". The "n" is more pronounced than the "w".
I agree. Had to double check the fast version before I changed it thinking it was a mutation. She definitely stopped between the words and said "naeth"
Does "waeth" refer specifically to the weather, or can I use it to forbode any situation?
gwaeth simply means 'worse':
Sounds like bydd CHI’N waeth yfory to my failing ears
It sounds clear on my phone and desktop.
A clue is that *bydd chi makes no sense here.