Observation: Soldier Peak

Observation Date
12/28/2020
Observer Name
Greg Gagne
Region
Salt Lake » Big Cottonwood Canyon » Soldier Peak
Location Name or Route
Reynolds/Soldier/Little Water
Weather
Sky
Obscured
Precipitation
Light Snowfall
Wind Direction
Southeast
Wind Speed
Strong
Weather Comments
Winds were from the southeast and only affected terrain above about 9,000'
Snow Characteristics
New Snow Depth
1"
Snow Surface Conditions
Dense Loose
Wind Crust
Melt-Freeze Crust
Rain-Rime Crust
Snow Characteristics Comments
A generous 5-10 cms including Saturday night snowfall. HS ranges from 30-60 cms.
Red Flags
Red Flags
Wind Loading
Cracking
Collapsing
Poor Snowpack Structure
Red Flags Comments
Numerous collapses and cracking today.
Avalanche Problem #1
Problem
Persistent Weak Layer
Trend
Same
Problem #1 Comments
The biggest concern with this problem is in areas with a stronger slab on top of the weaker facets.
Comments
Route today was standard mid-BCC tour: Reynolds, Little Water, and Soldier. Winds were light below about 9k, but plenty of wind-affect above that elevation. Fresh wind slab were 1F or P-hard, and up to 30 cms thick. Easy to get cracking in areas with fresh wind slabs, and noticed a large, natural crack on a NW aspect with a fresh wind slab sitting on top of facets. Had this been a steeper slope, it would have been a natural avalanche.
The snowpack in mid-BCC is shallow and incredibly weak with HS ranging from 30-60 cms. The slab on top of the weak facets is 15-30 cm and up to 4F hard.
In wind-affected terrain along the upper ridges (Reynolds and Little Water through Wilson) there were plenty of fresh wind drifts on top of these weak facets with cracking and collapsing on wind-drifted aspects. It is this type of terrain that I'm most concerned about as there is a much-stronger slab atop the weak facets.
Photos of cracking:
Dug several pits and most were ECTN (no propagation) but this pit on a slope adjacent to one that I had just gotten a huge on was ECTP18, failing 30 cms down in very weak facets.
As the weak snowpack adjusts, it is getting harder to trigger avalanches that fail on the persistent weak layer. But I would be especially cautious in wind-affected terrain at the mid and upper elevations where the recent winds have created fresh drifts on top of these weak facets.
Today's Observed Danger Rating
Considerable
Tomorrows Estimated Danger Rating
Considerable