Just to be clear, if one believes in a man-made influence or not, global warming manifests itself in an approximate 2C temperature increase in overall Earth temperature. It has important ramifications at the poles in terms of ice-pack, but the resultant changes there then lead to changes in global weather patterns.
I'm not going to say that snow in Vegas is proof of global warming, but it similarly has nothing to do with refuting it either.
growing up in tennessee (born 1975) it would snow every winter, sometimes feet of it. it's almost become a rare occasion that we get snow now. a few inches if we're lucky. global warming? i have no idea, but something's different...