Observer Name
Bill Nalli
Observation Date
Tuesday, January 5, 2021
Avalanche Date
Tuesday, January 5, 2021
Region
Salt Lake » Big Cottonwood Canyon » Silver Fork » Silver Fork Headwall
Location Name or Route
Silver Fork Headwall
Elevation
9,900'
Aspect
North
Slope Angle
40°
Trigger
Skier
Trigger: additional info
Intentionally Triggered
Avalanche Type
Soft Slab
Avalanche Problem
Persistent Weak Layer
Weak Layer
Facets
Depth
16"
Width
25'
Vertical
400'
Snow Profile Comments
This profile has similar characteristics to the avalanche but is on an adjacent easterly aspect in West Bowl. The well documented poor structure exists in most areas travelled. The upper Cottonwoods is pushing 80-100 cm HS and the strength of the slab over the weak layer is causing the avalanche conditions to be more stubborn. Stability tests continue to include propogation but only after you remove the strength of the crust and isolate a column.
Comments
I stomped on many cornices and ridgeline pockets today from Twin Lakes Pass to Patsey Marley and then along the Emma Ridge. The best word to describe things is stubborn. Without wanting to get out onto the steep spot on the slope at all, I wasn't able to get anything to move until I got to the heart of the Silver Fork Headwall where the slope angle approaches 40 deg. This slide is on a N aspect at 9900'. It's also a repeater.
Comments
Overnight SW winds were predominately loading N thru E aspects along the Emma Ridge but as the wind shifted to the west and finally northwest, portions of the ridge began reloading the south and east aspects as seen in the following two photos. Crossloading was also noted along the skiers right sides of the Emma gullies.
Comments
Cracking and collapsing continue. Hazard in grizzly, twin lakes, silver fork and emmas seemed like a solid CON (3 of 5) today and will be similar tomorrow. Slightly stronger snowpack than PC ridgeline and periphery.
Coordinates