Observer Name
Tim/UAC
Observation Date
Tuesday, January 31, 2023
Avalanche Date
Monday, January 30, 2023
Region
Salt Lake » Big Cottonwood Canyon » Mule Hollow
Location Name or Route
West Willow Ridgeline / Mule Hollow
Elevation
9,400'
Aspect
Southeast
Slope Angle
40°
Trigger
Natural
Avalanche Type
Soft Slab
Avalanche Problem
Wind Drifted Snow
Weak Layer
Facets
Depth
20"
Width
150'
Vertical
250'
Comments
A UAC forecaster visited this slide on Wed, Feb 1st - additional notes from the UAC:
The avalanche failed on a S/SE facing aspect at 9400'. This slide failed as a slab of wind drifted snow on a layer of small grain facets above a solar crust. The slab was between 10-20" deep. While it is hard to tell if it failed on small grain facets that were formed by radiation recrystallization, the setup seems. Small grain facets exist below the crust as well. Radiation recrystallization was occurring on the surface above the crown.
Notes from Tim: This morning before work I got in a quick Beartrap Aspens lap. From the ridge summit of Aspens, around 8800 feet, I noticed a large southeast-facing slide off of the West Willow Ridgeline into Mule Hollow. I've skied that aspect and area several times this year, but in less sensitive snowpack conditions, and was personally surprised to see a slide there, especially since the WBSkiing app has this area labeled white, aka not steep enough to slide. It's a good lesson to use the app only as general guideline when observing slope aspects and steepness.
If I had to guess, I'd say the slide is a few hundred feet long and wide, and several feet deep. Based on where I was standing on the lower ridge summit below, I'd guess the cause was natural due to heavy wind loading from the most recent storm, and that this slide probably happened over the weekend. I did not notice any tracks going in, or near, the slide path, so I did not feel it was necessary to ski into Mule Hollow and do a proper beacon search. If I had seen tracks going into the slide, I probably would have done so.
Looking forward to the snowpack healing up again to sneak in some bigger lines. Stay safe people.
Comments
The photo below was submitted separately by C. Galt
Comments
Photos below taken on Feb 1 by UAC staff
Coordinates