The west ridge is a short, year-round choice for climbing Atlantic from the west side. During summer, the ridge is a simple class 2 scramble with little in the way of technical excitement. During winter, the ridge becomes a more exposed mountaineering challenge due to knife-edges and cornices created by wind and snow. Further adding to the winter challenge is route-finding when approaching the ridge. Although the ridge can be obtained by avalanche-safe routes, the climber must exercise "thread the needle" precision to do so. Winter climbs are probably best executed during periods of low avalanche danger.
Atlantic's west side is accessed from CO-91. The trailhead is approximately 5 miles south of Copper Mountain at Mayflower Gulch and is also used to climb Crystal, Pacific, Fletcher and Drift. A large parking area is located immediately east of the highway. During summer, 4WD vehicles can proceed up the valley for an additional mile.
From the trailhead, proceed up the Mayflower Gulch 4WD road for over a mile. When directly across from the mouth of Pacific Creek (an obvious drainage along the north side of Mayflower Gulch), cross the willow-choked fields. Climb high along the shoulder of the ridge above Pacific Creek. Eventually turn right and climb to a flat spot on the ridge near 12500'. A steep talus step in the ridge will loom above. Climb the step to 13000' then proceed along the gentler, narrow ridge. A final steep section above 13400' will be the only other obstacle before the summit. Aside from a few small bumps in the ridge, there are no false summits. During winter, expect extremely narrow passages and at least one cornice near 13400'.
A snow knife-edge during spring conditions.
During winter, a safer approach can be made via Mayflower Hill. Climb the hill along the northwest side of Mayflower Gulch until above treeline. Proceed along the gentle ridge, passing a 12420' summit. Descend into Pacific Creek Gulch to about 12200'. Traverse south across the gulch toward the west ridge. A snow slope must be climbed to reach the flat spot in the west ridge at 12500'. Chose a line of ascent carefully as several parts of the slope are steep enough to slide.
An ice ax is a good idea for much of the year when snow is present. Crampons will generally be unnecessary, but when the snowpack is consolidated, they may be an insurance policy for traversing across snowfields to avoid the cornices along the upper ridge.