The cat is screaming for many reasons, some of which may include but are not limited to: you are 0.05 seconds late for breakfast, you just said “no tuna today”, it yearns for total destruction of all life itself, it understands the financial state of the world, or because you dared to look at them the wrong way.
We had a scary experience with a possum once. We used to feed a clan of stray cats in our neighborhood, and we even built them small homes out of plywood for when winter came. We would often reach inside to get them to come out, and once at night, we reached inside and felt something strange. We got a flashlight, and turns out there wasn't a cat inside, but a very scary-looking possum. We screamed.