The mountains in S Colorado influence our weather year round – during snow season they can either help or hurt our chances of seeing a heavy snow. When we have upslope flow they help things along quite a bit.
Under normal circumstances air at the surface is warmed and begins to rise. As it rises it cools and water vapor inside of it begins to condense. Eventually this leads to rain and snow. When we have an upslope flow the mountains and the wind do all the work and can create a heavy snow event without a strong storm present.
When winds push moist air up the slope (upslope flow) of a mountain the terrain lifts the air, not heating. This forces the air up, cools the air and the water vapor condenses as usual. This creates a sort of mountain “snow machine” as long as the upslope flow and moist air are in place.