Climb this steep hill finding the best route you can, and come back to the stream as soon as the brush seems to lighten up. At about 9,900 ft you should be back pretty close to the stream and you should be able to find a climber’s trail that parallels the stream. Follow the stream up into a big grassy meadow at about 10,100 ft. Continue following the stream all the way through the meadow to the northeast. At the upper end of the meadow the stream enters a forested area again, but it is easy to follow the stream through the trees as it climbs and turns again to the east. Keep following the streambed as it starts to climb out of the trees. Enter another long skinny meadow with trees on the right and rocks on the left.
At the upper end of this skinny meadow, elevation 10,500 ft, the meadow ends and there is a long rocky gully which is the continuation of the streambed heading up to a V notch on the ridgeline above. This is your objective, the V notch, where it tops out at about 11,500 ft. There are a few cairns at the bottom of this gully and in places a faint climber’s trail. Follow this as best you can. About half way up, the gully gets steeper and there is a climber’s trail that does several switchbacks through this section. Keep making your way up to the top of the ridgeline.
At the top of the ridgeline, the route becomes very narrow and bends around to the north again. This is where you get your first glimpse of the summit of Mount Warren. You can see it straight ahead with a small weather building on the summit. Now the good news is that you get to leave the rocky gully. Do not continue straight ahead towards the summit up the rocky gully. Instead, climb the slope to your right, or east, and gain about 100 ft of elevation up to a broad ridgeline with stable footing. Follow this broad ridgeline to the summit. There is an interesting hole in the ground that is between Mount Warren and Lee Vining Peak to the south. It is marked with elevation 10,822 ft on the topo. I wish I had explored it when I was up there.
The total hike is about 7.5 miles and gains about 3,300 ft. The round trip took me 5.5 hours plus lunchtime on the summit.