Headlamp by Zack Fields
The Thin White Line is a classic Anchorage ski objective that runs nearly from the summit of Avalanche Peak to Ship Lake below. Although it is approximately eight miles from Glen Alps each way, the couloir is easily accessible by bike--either during spring crust conditions or in early summer when the Powerline Trail melts out.
To access the Thin White Line, simply head out the Powerline trail from Glen Alps. In spring, try to nail crust conditions so you can fat bike up the valley rather than staying on the rutted trail. Ditch bikes around the bottom of the hill that leads up to Powerline pass. In the spring, it can be simpler to skin up and over the low pass that separates Ship Lake from Powerline valley, then boot up the couloir. In early summer, it may be more efficient to continue out the Powerline trail to Powerline pass, then hike along the ridgeline to the top of the couloir. This ridgeline ramble is fairly straightforward if it’s clear of snow, but would be quite slow in winter and spring.
“Thin” really only describes this run in early summer. In spring, it’s a comfortably wide couloir that opens up into a mellow pitch halfway down before constricting again above the apron. I’ve seen avalanches from the upper couloir that nearly, but not quite, washed down over the lower constriction. Particularly since this chute is on the lee side of the mountain relative to prevailing winds, it is important to be cognizant of recent weather activity--not just precipitation, but the frequent winds that howl over and around Avalanche peak.
When the snowpack is safe, it can be relatively quick to skin up the apron and boot up the roughly 1,800 feet line, at least if there’s not a massive cornice at the top. There’s a safe zone to wait below the top third of the couloir, to skier’s left, and above the mellow slope in the middle of the run. A medium to large avalanche in the top half of the run could have a high likelihood of lethality, since there are cliff bands below much of the couloir.
Unfortunately, there’s often a fairly brief period of time in which crust allows biking up Powerline valley, but it’s worth taking a shot at Thin White Line during this time to find powder on the northwest-facing chute. Later in the season, expect much firmer conditions.
I get excited any time I’m at least one ridgeline away from the road system. Though it’s close to town by bike, Avalanche peak and the Thin White Line feel wild. It’s a long, exposed ski line that descends to distant alpine lake. The magic of spring crust, or convenience of a summer trail, makes it possible to explore such a wild place in little more than half a day.