First, take a look at the cold air coming in with this storm, really, unusually cold as -1F air sweeps in on strong winds at 10,000+ feet.
Confidence is pretty good, based on intuition and some runs of the computer model returning favorable data that is in line with thinking, for a top to bottom snowfall at Aspen, snow accumulating in town for the first time this season (and snowfall for all of western Colorado, lower valleys also). The core of this storm starts out with temperatures of as cold as -20c/ -5F dropping into Montana on Wednesday, and this cold pool of air pushes southeast and across Colorado with snow and cold, some of the upper mountain areas seeing 6 to 12 inches (15-30cm) of snow on Thursday and into early Friday before clearing out. Friday morning and day look COLD, and it will feel and look like mid-winter in early October. Meteorologist/ Chris Manly
Check out the details here: http://snowforecast.com/usa-forecasts/southwest-usa/colorado/snowmass-aspen/