While we were unable to actually reach the summit from this route because of high ridge-top winds, we felt it was useful to include this route as an alternate to the longer approach route that includes T.11 and Three Fingers. This way, UN 13,159 can be easily done as a solo summit.
From the trailhead, hike steeply uphill on a good trail that will take you through 15 switchbacks. Up until about switchback 8, the distance between each tends to be rather short. After #8, the distance begins to lengthen out. At 11,650 feet, the trail leaves the last trees and climbs steadily west up the valley. Point 13,051 is clearly in view at the head of this valley. The trail climbs to within about 200 feet of a saddle between Pt. 13,051 and Pt. 12,740, then turns north to go up and across a pass between Pt. 13,051 and Pt. 12,692. One way to reach UN 13,159 would be to leave the trail and hike up to the saddle between Pt. 13,051 and Pt. 12,740. Then, contour NW over to another saddle between Pt. 13,051 and UN 13,159. From there, finish on the rocky Class 2 ridge.
Another way to climb UN 13,159, would be to continue on the Columbine Lake trail over the saddle between Pt. 13,051 and Pt. 12,692.. Walk on past this saddle another .4 mile until your north of the saddle between Pt. 13,051 and UN 13,159. Turn south and head up first tundra, then talus to that saddle. At the saddle, turn west to finish on the rocky ridge to the summit. From this summit, you'll be able to see Columbine Lake in the distance. If you have time, continuing down the west ridge to another saddle and then dropping NW down to the lake is well worth the time & effort. This is one of the most uniquely colored lakes anywhere in Colorado. There are some camping opportunities around this lake.
Links to other information, routes & trip reports for this peak that may be helpful.