Yes, precipitations is a Scrabble word!

Noun

1. The quantity of water falling to earth at a specific place within a specified period of time
2. The process of forming a chemical precipitate
3. The falling to earth of any form of water (rain or snow or hail or sleet or mist)
4. The act of casting down or falling headlong from a height
5. An unexpected acceleration or hastening
6. Overly eager speed (and possible carelessness)