I would suggest in addition to your kit your are wearing as a minimum you carry a dry top pref long sleeved, a waterproof jacket, gloves, hat/buff, map, phone (charged and with an ICE number in the phonebook), A little food additional to what you will consume whilst running.
Basically if it all goes horribly wrong you will most likely have a wait until someone can get to you/finds you. Think of what you would want to keep you warm and as comfortable as possible.
Edited: 24/09/2012 at 14:11