Pro Field Report

Basic Information

Observation Details

Observation Date:
January 7, 2021
Submitted:
January 7, 2021
Observer:
SAC - Savage, VandenBos
Zone or Region:
Galena Summit and Eastern Mtns
Location:
Spring and Cherry Cks (7000-10000', SW-W-NW)

Signs of Unstable Snow

Recent Avalanches? 
None Observed
Cracking? 
Isolated
Collapsing? 
Widespread
Widespread collapsing throughout the day, mostly 2-10m from the trigger point and a couple more extensive collapses.

Bottom Line

Thin snowpack (around 2 feet) with the widespread weak faceted layer. Not much of a slab below 8000' (too thin and soft), but definitely enough slab height and stiffness to have persistent slab avalanches above about 8000'.

Media/Attachments

https://www.instagram.com/p/CJw3PtNlyDa/

Advanced Information

Weather Summary

Cloud Cover:
Partly Cloudy
Temperature:
teens and 20s F (estimated)
Wind:
Light , NE
New/Recent Snowfall:
2-5cm (1-2") past 24 hrs

Skies ranged PC to MC, some flurries at times. No active wind-loading, and minimal previous/recent wind-loading. Still plenty of snow available for transport. Low elevation clouds indicated northeasterly winds, winds were calm to light (a rare Boulder treat).

Avalanche Observations

Spotted some small mid-storm debris piles, likely from thin wind slabs. No other significant, unreported activity observed.

Snowpack Observations

HS=40-90cm, mostly 60-90cm from 8000' to treeline around 9600'. Top of 12/11 FC was around 20-30cm above ground, with 35-55cm soft slab on top of that. Typical wind-hammered Boulder Mtns snowpack at/above treeline - no collapses in true alpine terrain.
Snowpit 8000' W-SW: ECTP1, ECTP3, PST14 end, PST11 end, CPST13 end, CPST10 end. All results were SP/Q1, about 40cm down.
Snowpit 9000' W: ECTP10 ECTP14, PST26 end, PST23 end, CPST23 end, CPST22 end. All results were SP/Q1, about 50cm down.

Avalanche Problems

Problem Location Distribution Sensitivity Size Comments
Persistent Slab
Isolated
Specific
Widespread
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5
 Layer Depth/Date: 35-55cm
Weak Layer(s): Dec 11, 2020 (FCsf)
Comments: Snowpit 8000' W-SW: ECTP1, ECTP3, PST14 end, PST11 end, CPST13 end, CPST10 end. All results were SP/Q1, about 40cm down. All PST and CPST were 100cm length columns. Snowpit 9000' W: ECTP10 ECTP14, PST26 end, PST23 end, CPST23 end, CPST22 end. All results were SP/Q1, about 50cm down. Location rose filled out based on observed terrain.

Terrain Use

Avoided avalanche terrain steeper than 30 degrees where the persistent slab problem exists. We poked into low 30 degree terrain at upper elevations where earlier winds had cleaned the early season facets down to rocks. In these areas the biggest hazard was ski/body damage.