Avalanche: Paradise

Observer Name
Matt Asay
Observation Date
Saturday, December 14, 2019
Avalanche Date
Friday, December 13, 2019
Region
Salt Lake » Mill Creek Canyon » Big Cottonwood Canyon » Porter Fork » Mill A » Elbow Fork » Mt Raymond » Paradise
Location Name or Route
Porter Fork-Paradise
Elevation
9,000'
Aspect
Northeast
Trigger
Skier
Trigger: additional info
Unintentionally Triggered
Avalanche Type
Soft Slab
Avalanche Problem
Persistent Weak Layer
Weak Layer
Facets
Depth
2.5'
Width
50'
Snow Profile Comments
~36°.
Comments
Skiing down off the backside of Mt. Raymond, and decided to drop a steeper part of Paradise than I've done before. The top was a bit wind loaded and we assumed it might break. My companion started down and, sure enough, maybe four turns into it I heard a "woomph" and saw the entire top break away. I yelled down to him and he easily skied out to the left while a river of snow swept down, pulling out all the snow down to the dirt and staying within the space between the trees that stood on either side. Clearly broke on the Thanksgiving layer. (Would have carried but not buried him, given the profile of the terrain and how much open space there was.)
We knew going into it that a slide was possible to likely (to certain), given that it ticked all the boxes (maybe 36°, NE-facing), and planned accordingly.
I skied down the ridge 50 feet to a less steep part and descended without incident.
My sense is that we should expect anything over 35° (at least) and N/E-facing will slide. Not assume that it *might* but rather assume that it *will*. This was an area that I knew pretty well, but that same slope profile on something like Gobblers (more open and few exit routes), or Holy Toledo (narrow and nowhere to go when it breaks) would be hard to mitigate the risk. I worry that people assume that if something has been skied it's therefore safe. It could simply be that the person skiing it a) has a different risk profile, b) knows the area and how to manage/avoid risk (Mark White and the Monitors/No Name Bowl comes to mind), or c) was ignorant and (fortunately) lucky. I've definitely fallen into that "c" category.