Front Range
AvalancheDrew Thayer · Jan 19, 2019 · Front Range
Weather
Wind from north, starting to snow lightly. The snowpack was heavily loaded with Friday's new snow and wind-loaded. I was also here on Friday mid-day, and it was then overcast, snowing, and blowing pretty hard from W/ NW. I don't know the snow rate, but new drift accumulation on open ground (snow + wind) amounted to a 1' deep skin track being almost completely covered after a 20 minute lap.
Snowpack
On Saturday (day of this observation), snow was heavy and wind-loaded, skis would sink in 3-6" but not break any crust/slab at this depth. By mid-day on Friday (day of slide) a soft storm slab was forming, which would break while breaking new trail, ~ 3" of soft powder falling downhill in a sluff.
Avalanche
I believe this same event was documented on Friday 1/18 with vague location details, so I'm providing these details and a photo to complete the report. (location description and travel pattern in 1/18 report generally match what we observed). To skinner's right of the main skin track that ascends directly S to the Butler Gulch saddle, immediately above treeline, there is a steep slope (descending from knob on ridge to the right/W) with rock bands and shallow gullies. Below this is a (very) low-angle, treeless zone that is commonly skid. We observed an avalanche crown ~300 ft up the knob's slope, where a crown had broken and snow had slid off to the ground surface, revealing grass and small rocks. The avalanche debris stopped in the first ~50 ft of very-low angle terrain. New ski tracks from saturday went under the same slope through this debris (!!) and since Friday's tracks were likely buried/erased we could not corroborate the Friday report's narrative, but it is easy to imagine that it played out as described. The start zone for this avalanche was on a very wind-loaded aspect (N, just E of a micro-ridge that was heavily drifted on the lee (E) side), and was up an increasingly steep convex slope from the low-angle area with tracks. We did not ascend to the start zone to get an accurate measurement of the crown; we estimate it to be < 2' and > 1'. I'm including this with details because this low-angle slope where the debrid ended (and the avalanche could have been remotely triggered from) appears very safe, and is frequently skid by parties that are not considering themselves in avalanche terrain. A good heads-up to the possibilities of remote triggering, and paying attention to "hangfire" above.