Follow the signs at the beginning of this trail for Buffalo Cabin Trail, then branch off to the right for South Willow Falls Crossover, or continue on Buffalo to the summit of Buffalo Mountain.
The trail stays inside the dense trees until you climb closer to treeline. Once above 11,800 you enter the scree field. This will take some maneuvering over many loose rocks, keep your eyes peeled for the cairns leading you to the summit.
Once at the top, take in a great view of the Dillon Reservoir and Summit County! There's some fun scrambling on the summit that will take you to the further point, which is not actually the true summit. You already hit the true summit at 12,777!