Does Northern California have anything like a native ferret? Because I just saw something that looked amazingly like one. Running, or more like loping, up a 280 embankment. Black, or at least dark enough to pass for it under partial streetlight. Too slim to be a cat, but about the length of a smallish one, and it didn't run like an oppossum, it ran like a ferret. It paused occasionally and looked back in my direction and I could practically hear the 'dook dook dook'.
I would have pulled over and tried to get a better look, but I had a cop next to me, and I also didn't want to startle it into running onto 280.