People often get worried about snow in the mountains and it is definitely something to be concerned with. But some of you east coasters get used to rapidly changing weather conditions like you get back there, and that doesn't happen so much in the mountains of the west. Or I should say yes, the weather can change fast, but the change is highly predictable.
Snow in the mountains almost always comes from storm fronts that come in from the North. That means the weather man can tell you days in advance whether it's going to be storming or not in the mountains. The time of year you will be traveling is still fall. Although there is a chance of snow that time of year, you'll be able to watch the weather reports and know if it's coming or not. So you can always plan to take a mountain route, and if the weather man says there is a storm on the way, then just change your plans and head south.