Roaring Cat (Why Do Cats Roar)
Roaring, hissing, or spitting indicates that a cat is very upset, scared, angry, or aggressive. Do not disturb this cat. Roaring or howling (which sounds like a loud, drawn-out meow) tells you your cat is in some kind of distress--trapped in a closet, looking for you, or in pain. If your cat makes this sound, please find them.

Why does my cat roar?
Generally, if you are unfamiliar with cat behavior or have never seen a roaring cat before, you might not understand why cats roar. Cats roar at other cats, people, objects, or even when alone. A cat’s roar can be alarming, and it should be. There are many different reasons cats roar, but they usually mean one thing: back off!
What does cat roaring mean?
Your cat can tell you how she feels not only with her voice but also through her posture. It's important to notice what your cat looks like when roaring. Angry or aggressive posture looks like wide-open eyes, upright ears, and an arched back. However, a frightened cat will have normal eyes, ears, and tail.
While you shouldn’t immediately approach your roaring cat, you can look at these different reasons why cats roar to see if they apply to your cat’s situation. Then, when you know the reason, you can better soothe or comfort her, potentially stopping the roaring.