Cupping, crowning, buckling — three words, three outcomes.
Cupping
Edges rise higher than the center because the bottom of the board is wetter than the top. Caught fast, cupped floors can often be dried in place with specialized mat systems and come back flat. This is the save.
Crowning
Center higher than the edges — usually what happens when a cupped floor gets sanded before it finished drying. Avoidable, and expensive when it isn’t avoided.
Buckling
Boards lifting off the subfloor entirely. That’s a long saturation and it’s generally past saving.
The Atlanta wrinkle
A lot of intown houses have original hardwood over a plank subfloor with a crawlspace under it. Water gets into all three layers, and drying just the top is how you end up doing this twice.