Hike the narrowing moraine between the ridge's S. face and the Bugaboo Glacier up and West. I've used the glacier for easier travel in places, but at least one major injury crevasse fall has occurred here. When you reach the cirque, climb the gully to the ridge crest at the low point between Snowpatch and that amazingly pointy sub-peak to your right.
The best descent takes you down the opposite side of the mountain, so don't leave stuff here. I've done the route in lightweight hiking boots to avoid having to switch between rock showes and heavy boots. It works out great, except at the crux.
Back on the crest, you're confronted with the wall in front of you. Climb the steeply-sloping ledge around to the right, over the Crescent Glacier side, then up to the bottom of the snowpatch slab.
Pass the snowpatch on the left for about 4 ropelengths. I've simul-climbed this section, setting pro where I can find placements while my partner cleans at the same time, a rope-length behind. It's not entirely safe, but the slab doesn't seem steep enough to justify breaking it up into pitches and doesn't have that much protection anyway. It felt too exposed to coil the ropes and walk. Do what's comfortable and live to tell about it.
At the top of the slab, traverse ledges to the right toward a large rock shaped roughly like a pear standing on its head. Climb the crack system behind it. In two pitches you'll traverse a slab left into a right-facing corner and up onto a very square block. You're looking at the crux here, and there's no mistaking it. On the almost-vertical wall in front of you is a perfect 2-inch (5cm) wide quartz dike. Problem is, it's way off to the right, almost out of reach. Stretch out there and pull yourself onto it to climb the next 15 feet (4-5m) on pinchgrips and toeholds. This is where I had second thoughts about climbing the dang thing in floppy trail boots. There's one bolt in the middle. Reach the roof and traverse left and up again. The alternative to the dike is the corner on your left. It's 5.8 when dry, but it was muddy and dripping when I was there.
Continue up the left-facing corner, then work left to the cracks that take you in a couple more pitches to the crest, just a few feet from the summit. Look down to the left as soon as you're on the crest. There's the gully you'll rappel to the Vowell Glacier. If I remember, you step down onto a ledge for the first anchor. But first continue north and sit on the summit.
The first ime I climbed Snowpatch, we rappelled the route. Big mistake. It's way too long, with way too many traverses. We had our headlamps on before we reached the ground. Go straight down that gully you passed on the left. It's the Krause-McCarthy route (5.8+). With two 50-meter ropes we cruised straight down the gully in four raps, then walked down easy slope to the edge of the Vowell Glacier.
The glacier has a wind-carved snow ridge parallel to the face here, about 50 feet (15m) high, and 200 feet (60m) from the face, as I remember. It's an easy walk along the crest north to the col. Incidently, the safest place I've ever been in the mountains in a thunderstorm was on this ridge. There's no way a direct strike would reach us when the mountain was right beside us and 800 feet above, and there's no way ground currents would reach us when we were on that ridge. I think.
From the col, descend the 600 feet (180m) to the Crescent Glacier. Don't head down the glacier straight toward the hut; cross it directly, then turn right and descend the moraine.