Not paranormal as such but definitely worth logging. Black squirrels aren't unheard of - they're usually just a melanistic variant of the eastern grey, and they've been spotted in loads of places they "shouldn't" be. But the Pacific Northwest is an interesting one because the local species there are different so it does raise questions about where it came from.
That said I've seen genuinely jet black animals turn up in places that made no sense and sometimes the mundane explanation doesn't quite fit. Has anyone got photos? Would love to see if the body shape matches a known species or if something seems off about it. Melanistic animals do occasionally get reported alongside other strangeness, which is why I'm not ruling anything out just yet.