Yes, howl is a Scrabble word!

Verb

1. Emit long loud cries

2. Cry loudly, as of animals

3. Make a loud noise, as of wind, water, or vehicles

4. Laugh unrestrainedly and heartily

Noun

1. A long loud emotional utterance

2. The long plaintive cry of a hound or a wolf

3. A loud sustained noise resembling the cry of a hound