Craig,
As a retired member of the U.S. military dealing with WOMD, there are major targets in the U.S. there are alost targeting predictions for those targets. The thing is you need to know the direction of the Normal prevailing winds. They will create a plume of contamination. In AZ they generally come from the west. If you move North or South you can remove yourself from the danger area. You still have to consider other large metropolitan areas to the west (LA or San Diego) who's plume will travel your way.

Yes you will run out out of supplies. Be sure of where you evacuate to. Is there water?, we live in the desert, is there game? and are you able to get that game?

My opinion is iodine tabs are great to prevent radiation sickness provided you don't linger in the contaminated area, and gas masks are useless. They give people a false sense of security.

Keep a decent supply of powerful antibiotics, i.e. cipro or keflex, iodine tabs, and have a plan to bug out to a safer area.