Plummeting or plunging.
autumn
Depreciate.
collapse.
epic fail
monsoon
ball
plunging
The word is undulate. It means rise and fall.
Another word for turned is rotated. Another is pivoted. The phrase "changed to" is also an option. Example sentence: Last fall, the leaves changed to red. Last fall, the leaves turned red.
yo yo yo yo man
trip,stumble,drop. go look in a thesaurus.
That child is about to fall off of the slide and collide with another child!