The South Summit Couloir is one of several steep snow couloirs on the NE Face of Lone Peak. It is a notable backcountry ski descent and excellent Spring/Summer mountaineering route.
See the Bells Canyon Trailhead
section. From here take the main hiking trail up to a large (15-20 foot) waterfall where the trail crosses the stream. It's easy to miss in the dark, so stay as close to the stream as you can and backtrack if the trail gets too faint (we bushwhacked up half the canyon because we missed this). From here continue on the trail until it peters out into a HUGE boulder field, then just boulder-hop for a couple miles near the stream until the terrain flattens out. Go past Upper Bells Canyon Reservoir and Lone Peak's NE face will come into view on the right (to the SW).
My ascent was in late June and about 2/3 of the climb was on snow. 2008 was a huge year for snowfall in the Wasatch so the route would probably be in ideal conditions most years between late April to early June. The later in the season, the earlier a start you'll want to get as the couloir forms some serious moats from snowmelt during the day.
Almost all of the rock was 4th class with an occasional easy 5th class move. The rock is surprisingly good for such a broken-looking face, and there should be ample opportunity for protection in the granite.
The couloir rises from about 10,000 feet to the South Summit for a gain of 1,100 vertical feet, all in about a quarter mile. This gives the climb an average angle of 40 degrees, with significant sections of the couloir between 50 and 55 degrees.
Crampons, a mountaineering axe and helmet. Those with two ice tools will want to use them for security in the steep snow. Depending on the season, snowshoes for the approach.
Most parties will probably want to rope up for the length of the climb due to its sustained steepness. Pickets would suffice and an ice screw or two might come in handy earlier in the Spring.