Jan, did you look at the lost pets site I gave you the link to? LOTS of good info there to help you.
I just KNOW he's close and wants to come back in but it is scary outside.
Your best bet is to find him in the wee hours. He won't come when called, but will respond to the sound of your voice talking in a normal tone.
Also, please try putting a litter box out on your porch for him with used litter in it - the smell will help him to stick close.
I know what you are going through and I wish I could help more!
Ari, come home to Meowmy ASAP, young man!!!