Front Range
AvalancheAnonymous · Mar 9, 2014 · Front Range
Weather
Steady west winds of at least 20-30 mph along the Continental Divide with gusts over 40 mph. Observed intense wind loading into gorges dropping off the leeward (east) side of the Divide. Wind-transported snow stung exposed skin. Bear Lake Snotel reports 42 degrees at 10:00 AM and 2 inches of new snow within the last 24 hours, although local totals may be significantly higher due to rapid wind loading. Clear skies. Did not measure height of snowpack.
Snowpack
Did not dig snowpit. Snowpack at site of avalanche felt hollow and punchy under skis. Pillow-like convexities observed near the top of many leeward slopes. Sun crust observed on south and east aspects. Surface hoar observed in wind protected areas. During ascent, remotely triggered a wind slab in the Corral Couloir that enters the north side of Tyndall Gorge while traversing approximately 20 feet from the couloir entrance.
Avalanche
My partner and I, both on backcountry skis, descended Andrews Glacier to complete a loop that began at the Bear Lake trailhead and traversed along the Divide south of Flattop Mountain. We made a faulty assumption that the primary avalanche hazard encountered on the descent route would be avoiding the steep wind loaded headwalls that border the low-angle Andrews Glacier, which we felt comfortable bypassing via a quick traverse across the lower runout of one of these steeper paths. However, just below Andrews Tarn, we encountered an approximately 200ft slope with a convex center bounded by steeper, concave sides. We were immediately concerned and skeptical about the stability of the slope, but found it to be a more palatable alternative to retracing our tracks up Andrews Glacier, which would result in much longer exposure to the runout we quickly skied past on the descent. Thinking we had identified a safe route, I began skiing on lower-angle slopes to skier's left of the slope's convex center, then began a cut to skier's right across the slightly steeper slope (35 degrees), aiming for a relatively flat area on top of a sparsely-treed knob. My partner watched from a safe position on top of the slope. Soon after beginning the cut, the snow whumpfed beneath my skis and I saw a slab break loose about 20 feet above me. I stayed upright on my skis, facing forward as the slab began to fracture and pick up speed for about 50-60 feet. I was quickly getting out of control as the slide began to accelerate toward a steep slope to skier's left of the knob. With verbal encouragement from my partner, I attempted to turn skier's right to reach the knob. Soon after initiating the turn, I lost my footing. I slid only a few feet before coming to a rest in a debris pile that settled on the flatter flank of the knob. I was probably carried about 75 feet total. I was uninjured and buried up to my boots, and was able to easily extricate myself. After reestablishing verbal communication with my partner, he skied the bed surface down to my position and continued our planned descent route. We traversed skier's right across the knob, then tucked in behind a cliff to avoid further exposure.