Willow BM/Mt. Silverthorne is part of a longer day-trip from a base camp at Deluge Lake and is sequenced with Snow Peak. One-way mileage and elevation gain are measured from the summit of Snow Peak. Round-trip mileage and elevation gain assumes completion of the sequence.
Some trip beta we had indicated that there was a use trail that would lead us from Deluge Lake to the top of Snow Pass to the east and above Snow Lake, but from Deluge Lake and vicinity we had not seen a clear sign of this trail. Without one, the trek through the endless, steeply sloping scree up to Snow Pass would be a difficult one, so it's worthwhile to find this trail.
From the east side of Deluge Lake head generally ESE, following a stream drainage, in the direction of Snow Pass, gaining some elevation through tundra and then ascending a steep, giant, boulder step to a bench-type boulder field SW below the south ridge of Valhalla. Cross the large, stacked boulders carefully, and start ascending on a steep, tundra slope just to the right edge of talus that comes off the cliffs above. As you ascend up in this sparse tundra, a clear path begins to emerge and then it abruptly turns east from the talus and begins a long, angling ascent toward the pass. We have included a Google Earth view to try and show this trail. It is actually visible on GE. With the advantage of this trail you can move quickly along and have little difficulty crossing the numerous scree fields. As you progress toward the pass, you may have an opportunity to see a number of mountain goats. They seem to enjoy the Snow Pass saddle. As the trail brings you to a few hundred feet under the pass, it climbs more steeply on braided trails created by both hikers and goats that lead up through gravel and small scree with poor footing. At the pass, spend a little time admiring the spectacular view all around. The peaks surrounding Snow Lake are unbelievably rugged.
From the pass, decide if you want to go ahead and climb Snow Peak now, or later in the day upon return from Mt. Silverthorne. If continuing on, descend directly toward the lake, at first with no trail, but lower down, you should pick one up that leads through lush vegetation, laden with flowers in mid-summer. If you've completed Snow Peak, descend the north ridge as you went up either all the way back to the Snow Pass saddle or shortcut down a fairly tundra-covered slope east off the north ridge at about 12,700 ft. and pick up the path to Snow Lake further down. This short cut has some rubble, but it's mostly good footing. The trail drops a good 400 feet straight down before angling off toward the north shore of the lake where it contours well above lake level and deposits hikers at the east end. It took one hour from our campsite to hike here (not including Snow Peak). Continue on from the lake, walking on down through more luxuriant vegetation and flowers, at the right time of the summer, a photographers paradise. The faint trail is difficult to follow at times through all the plants. It stays on the south side of the drainage. Follow it until you come to a nice, level area where the creek turns to the south and the stream has a few nice ponds.
On the east side of this creek, there is a steep and fairly narrow gully that comes down from above and provides access to a broad, gently sloping terrace SW of Willow and its’ south ridge. The ascent up this gully is a good scramble through typical Gore rocks and overgrown vegetation. Frequent use by the local goats has left a good path to follow though. About 500 feet up, the gully levels out and opens into the broad tundra basin above. Walk east toward the south ridge of Willow BM, gaining the ridge at a saddle. Turn north, hiking up through a tundra, embedded boulder mix on the ridge. You have the option of continuing on this ridge all the way up. As for us, we elected to do the following: About 200 feet up, contour right and in the direction of a tundra filled bowl. Hike on up through the tundra and grass a good 300 feet in elevation to the base of a large, rubble-filled couloir that leads to almost the summit of Willow. This couloir is much easier said than done, however. The upper couloir was one of those rubble-filled types where most every rock is precariously placed atop another and you never have secure footing. There is also plenty of “two-steps-forward, one-step-back” scree to deal with. Higher up, Carrie continued in the rubbly gully while Tim ventured onto the east side and found he could make more secure progress scrambling on rock ribs above the gully. We both emerged to the summit plateau at about the same time, but a little apart from each other. From here, it is just a short stroll north to the Willow BM/Mt. Silverthorne summit. It took us about 3 hours from the Deluge Lake campsite.
Bonus Points: Across the high bench just below and off to the east about a half mile is the 13,333 ft. pinnacle that from Silverthorne, some refer to as Mt. Silverthorne. The name "East Thorn" has been given this point to distinguish it from the true Mt. Silverthorne summit. From the bench level, this challenging spire of rock rises nearly 300 feet and along with the previous urging of a peakbagging friend, it beckoned us to ascend its heights. So we decided to give this little challenge a try and headed on over there. The bench terrain is mostly large, flat boulders with interspersed tundra. We moved fairly quickly across up to a point, but then had to gain some elevation and begin a contour over to the base of East Thorne that took us through a relentlessly slow complex of stacked boulders and rubble, that greatly slowed our progress – so much so that it required overall, 1:15 to make the entire round trip that only covered a mile at best. After dealing with all the boulders, there were two notches to work our way through before reaching the base of the pinnacle. From there, we scrambled our way to the summit on 3rd, and even 4th class pitches with some exposure. It started out fairly easy at the base but quickly advanced into some 4th class work. There were a few route decisions to make and about 2/3rds of the way up, we had to make a couple of low 5th class moves to continue. Near the top, there was a narrow, catwalk-like ridge section with a large block to work around and then a final scramble onto the small, rock summit. Admire the precipitous drop to the south. Though it had not taken long, this little pinnacle had been a fairly exhilarating climb. After a very short break, we carefully descended, taking a somewhat different route back down that avoided one of the exposed, 5th class moves and negotiated the boulder fields back to our stashed packs. We exercised a lot of caution, having neither rope or helmets for protection. We were a little worried that having been gone so long, a marmot might have explored our packs for some food, but we found nothing damaged. Including a side trip to East Thorn will add 1.2 miles RT and about 250 vertical feet.
For the return trip, basically return as you came. Another "bonus point" activity would be to traverse west from Silverthorne to UN12,904, aka: "Hail Peak." See reports on LoJ for that traverse. The same summit could also be ascended from east of Snow Lake as well. Overall, it's nearly 3 miles from Mt. Silverthorne back across Snow Pass to Deluge Lake.
Links to other information, routes & trip reports for this peak that may be helpful.