It's from 台风 (sounds like typhon, more than it sound like typhoon tbh) and tbh the "ty" part might just be from "dai" meaning "big", so just "big wind", but I've heard it's just as likely to be "wind from Taiwan", the same 台 ty as in 台風, Taiwan.

And yeah, this map proves that Taiwan (and northern Philippines) is the world capital of strong typhoons.