The advancement of global tree lines in response to climate change has raised questions among researchers about tree recruitment at elevations beyond tree line. This study aims to help understand this process by examining the progression of an abrupt tree line of engelmann spruce on the western slope of Pikes Peak, in Colorado Springs, Colorado. Methodology for this study includes drone photography, GIS mapping, dendrochronology, tree growth measurements, and soil moisture measurements. The results of our examination suggest that the three main mechanisms controlling advancement at our tree line include a leeward eddy when upslope winds interact with the tree line like a shelterbelt, a spiral eddy when winds are parallel to tree line, and cold air damming of katabatic winds against the tree line at night. Our examination of the vegetative response of trees at our tree line suggests that the most healthy recruitment is occurring on the southern edge of our transect and at the upper extent of the area expected to be protected by the tree line. We have found that trees and limbs that exist within the cold air dam at tree line have experienced decreased growth compared to trees outside of this layer of cold air.