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Avalanche: Main Days

Observation Date
Tuesday, December 17, 2024
Avalanche Date
Tuesday, December 17, 2024
Region
Salt Lake » Big Cottonwood Canyon » Days Fork » Main Days
Location Name or Route
Main Days
Elevation
10,200'
Aspect
Northeast
Trigger
Skier
Trigger: additional info
Intentionally Triggered
Avalanche Type
Soft Slab
Avalanche Problem
Persistent Weak Layer
Weak Layer
Facets
Depth
2'
Width
800'
Vertical
1,000'
Comments
My partner and I went into days fork yesterday to check out the snow pack in the upper elevations. We planned to head up to main days and to see if any of those shots were feasible options.
While putting the skin track into upper days we noticed some signs of instability but nothing out of the ordinary for this shallow faceted snow pack. When we topped out on main days the snow on the northeast aspect main lines had clear signs of wind slab texturing. On the shoulder of the ridgeline we were able to get shooting cracks to extend about 15-20 ft out onto the slope by stomping near the edge of the slope. We kicked down a few small cornices but were not able to trigger anything.
While the slope was clearly not safe to ski we progressed to the top of main days as our plan was to ski the SE aspect near the ridgeline back to safety. At the top of main days my partner stomped near the edge and the whole slope immediately fractured and began to slide. The crown was about 2' , 100ft wide and ripped down to the ground in parts. The avalanche moved at an alarming speed and snapped a few trees. It's hard to say how far it went but if I had to guess I'd say at least 1,000ft.
As we were watching it slide we noticed that the lines to the north along the ridgeline that are more east facing also began to slide. It looked like they were being triggered sequentially, like dominos, about 800ft north along the ridgeline. None of these slides looked to be quite as deep as the initial one, but they still went pretty far. At this point we turned around and headed down the southeast aspect and stuck to safer terrain for the rest of the day.
Coordinates