The adverb extraordinarily indicates that something has an extreme quality or has been done in a manner well beyond what is typical. Extraordinarily wet, heavy snow can pile up on power lines, causing them to snap.
The word extraordinarily can be broken down into two main parts. The first part is extra, meaning "beyond." The second part is ordinary, meaning "usual" or "normal." So something done extraordinarily well is done beyond what is normal or typical. For example, an athlete playing extraordinarily well in a game will contribute more to the team than the average player.