Yes, yowl is a Scrabble word!
...and is worth 10 points in Scrabble, and 10 points in Words with Friends
yowl
Verb
1. Cry loudly, as of animals
2. Utter shrieks, as of cats
Noun
1. A very loud utterance (like the sound of an animal)
What Scrabble words can I make with the letters in yowl?
3 Letter Words
2 Letter Words