The section of the Pacific Crest Trail (PCT) north of Snoqualmie Pass is overrun with hikers every summer weekend, but put a few feet of snow on the trail, and the crowds ignore it. That's great news for snowshoers because the trail is easy to get to and enjoyable for snowshoeing. The route to Commonwealth Basin follows the PCT for more than 2 miles through shadowy old-growth forest--with an occasional break in the trees for views of the surrounding peaks--before setting off on a smaller path into the wide, rocky basin at the base of Red Mountain.

Commonwealth Basin affords excellent views of the iron-rich flanks of Red Mountain, although snowshoers will be at a loss to explore the source for the mountain's name since it is covered in a deep quilt of white snow all winter. There are also excellent views up to Kendall Peak and Snoqualmie Mountain from the basin.

Just north of the freeway underpass, a small snow-covered road climbs off to the right. Snowshoe up this road into a wide summer parking area at the PCT trailhead. The trail leads off from the east end of the parking lot, rolling up through thick forest on a long traverse to the east before looping through a switchback corner near 0.7 mile and climbing northwest. After looping through a couple more short switchbacks, the trail rolls north to a junction at 2.5 miles (4000 feet).

An alternate route, when snow is very deep, is to snowshoe up the narrow valley directly above the PCT parking area. Stay left and climb through the trees, keeping the small creek basin on your left until reaching the broad mouth of Commonwealth Basin.

The route to this point is easy to follow because the trail corridor is wide and obvious in the heavy forest. The trail stays under the forest canopy nearly all of the first 2.5 miles, although it does cross the base of a large avalanche slope and then recross the slope higher up after climbing through a switchback. Cross this slope with care, and if the avalanche danger is higher than moderate, avoid the area. The point where the trail crosses the slope is on the run-out section of the chute rather than the trigger area, so it is unlikely that you will trigger a slide here, but caution is still required.

At the trail junction, stay left--the PCT climbs steadily to the right--and follow the Commonwealth Creek valley up into the basin. The trail is a long, straight ascent up the valley, climbing gradually as it enters the basin. The forest thins, and finally falls away at 4 miles, leaving you on open slopes at the base of Red Mountain. Potential for avalanches exists here beyond timber line, so care and common sense must be used in heavy doses. If the snow is stable and safe, it's possible to scramble up to the 5300-foot level (about 5 miles from the trailhead) at a low saddle on the ridge between Red Mountain and Lundin Peak. The last 0.5 mile of climbing is steep and should be attempted only by those with experience in snowshoe mountaineering.

Author’s Rating: Backcountry
These routes follow topography rather than trails or roads. Skill with a map and compass is essential. A variety of conditions may be encountered along backcountry routes, including steep elevation gains and losses. These routes require complete competence in winter survival skills, avalanche and snow condition evaluation and some basic mountaineering skills.