Still looking for Jack ...
I found a similar cat sleeping in the box left outside for him a couple of weeks ago during the very cold day we had. I called the Humane Society and I think they came and got him as I haven't seen him since.
I still find myself scanning the neighbourhood for him as I drive through. We miss him very much as does our other cat who seems to be more clingy these days, especially when we get home from work. Might be a good idea in the New Year to start thinking of a new companion for him.