Climbers, hikers and ski-lift riders all know – the higher you get in the Rockies, the colder it gets. Temperature change doesn’t only have its affects on exposed appendages, but also controls the precipitation we all love to play in, here in our mountain paradise. When heavy precipitation is expected, abundant moisture is usually present in the atmosphere’s lower levels, but sometimes, substantial amounts of precipitation can fall with less moisture available in the air if adequate lifting is present. In what is called an “upslope flow,” air rises and cools as it is forced to ascend the Rockies’ higher terrain. Cooled air then condenses, forming clouds when it cools to dew point.
The eastern Rockies often experience upslope conditions during the winter. Winds blow across the prairies from the East, losing their moisture along the way. When the dry air hits the mountains, it is forced up the slopes quickly. The temperature drops as the air rises and condenses to form clouds. As the air continues to be forced up the mountains, the clouds get heavier and soon precipitation begins. Depending on temperature, precipitation will fall as snow or rain. Because the air mass began dry, the snow that does fall will be light, dry and fluffy. Affectionately dubbed “champagne powder,” it is greatly sought out by ski-driven connoisseurs.
