Platinum Peak via Bullion Basin is the primary way to the summit of Platinum Peak. Using the Bullion Basin trail you many times will have a well laid out winter path to with 900 feet of the summit. Often this trail is so kicked in that snowshoes are nessesary until reaching the higher elevations. From there it is 900 foot snowclimb that at times requires climbing a 45 degree slope. In winter this can be a moderate avalanche danger so really check the avalanche danger before attempting this peak. If the danger is high go for nearby Bullion Peak instead where much of the avalanche danger can easily be avoided.
Though the trail to Bullion Basin is fairly popular the summit of Platinum Peak is surprisingly not very popular. The lack of popularity is not because of the lack of views. In my opinion Platinum Peak has better views than Bullion or Norse Peak to the north. It at least rivals its neighbors in views and quality of route.
VIA THE CRYSTAL MOUNTAIN SKI AREA: From Enumclaw take 410 east for 33 miles until just before reaching the gate of Mt. Rainier National Park. In winter this road will be gated just passed the Crystal Mountain Road. Make a left on Crystal Mountain Blvd (7190) (paved) go roughly 6 miles to the main ski area.
The best way to reach Platinum Peak is from Bullion Basin. When you arrive at the ski area, walk to the left (east) of the main lodge. From there take a number of roads up to the Bullion Basin Trailhead (see map). Once on the trail take the Bullion Basin trail all the way up to Bullion Basin which is at the elevation of 5800 feet. Once in the Bullion Basin you must climb up in such a way that you end up in the south saddle between a small peaklet a couple yard to the south and Platinum Peak to the north.
Be aware in winter you will be crossing open 45 degree slopes that could become hazardous in high avalanche danger. Bullion Peak does shadow the southern slope which in January prevents the slope from heating up too much but in March this slope swill probably heat up much more and in full daylight could be an avalanche risk. Try to go straight up from here if safe.
Avoid going to the ridgeline and then traversing to the summit in winter. Rising to the ridgeline caused me to traverse an even steeper dramatically more dangerous avalanche slope where a slip could cause a fall of over 800 feet. You might be able to avoid this by going through the short trees but then you risk tree rings.
If climbing this peak in winter, an ice axe, traction devices and snowshoes are absolutely required. You will encounter steeper slopes and variable snow conditions even on the best of days. Once on the saddle section of Platinum Peak, head directly to the summit where terrific views await.
In winter this peak requires an ice axe, and snowshoes. Depending on the quality of snow the route up may also require crampons. In the dead of winter though on a consistant snow year you can usually go without but if this hike is in early spring or there is a lot of heavy freezes it might be a good idea to bring them.
External Links A trip report on this summit
The Crystal Mountain Resort Page. A great sight on information, local weather and snow conditions.