One of Breckenridge Resorts’ greatest strengths is its ginormous size. Opening the mountain up for the winter takes a village, and the work starts as soon as the mountain closes for the season. Mountain operations create a plan for which lifts and facilities need repairs, along with working on new lifts. Snowmaking typically begins in October, as it is trying to become a main player as one of the earliest mountains to open in Colorado.
Breckenridge described this process in a new video: Opening The Five Peaks. In the video, the various heads of mountain operations discuss what it takes to get the large Colorado ski resort open each winter. The shortage video from Breckenridge is below. 
Image/Video Credits: Breckenridge Resort