Pro Field Report

Basic Information

Observation Details

Observation Date:
December 16, 2021
Submitted:
December 17, 2021
Observer:
Pro
Zone or Region:
Banner Summit
Location:
Copper and Banner Summit (7,000'-9000', SE-NW)

Signs of Unstable Snow

Recent Avalanches? 
None Observed
Cracking? 
None Experienced
Collapsing? 
None Experienced

Snow Stability

Stability Rating: 
Fair
Confidence in Rating: 
Moderate
Stability Trend: 
Steady

Bottom Line

The older snow that has remained in this area has been handling a consistently increasing load fairly well where we traveled. Any mid-storm density instabilities from earlier in the week have appeared to have settled.

My primary concern remains the facet/crust layers that comprise the bottom ~60cm of the pack. The subtle dance between persistent weak layer and shifting tensile strength of slab is happening here. Terrain of higher consequence and northerly aspects off the top of Copper and nearing/above treeline should be avoided, particularly as the new snow settles and winds shift or increase.


Advanced Information

Weather Summary

Cloud Cover:
Overcast
Wind:
Light , W
New/Recent Snowfall:
2 week settled HN total ~85cm

S-1 from 9am- 3pm, increasing winds on the latter half of the day.

Clear skies and low temps will likely work this new snow surface, particularly where it fell lower density, and cause some issues with more snow headed in next week.

Avalanche Observations

Low visibility- though none observed along Lowman Road or in visible Copper and Banner zones.

Snowpack Observations

Banner Summit had an average HS of 120cm above 7000'. Copper held an average HS of 140cm, nearing 180cm on N aspects at 8500', Both locations have facet/crust layers that hold the potential to cause persistent slab instabilities and overall structure leaves me wary, but remained unreactive in tests yesterday.

Banner pit: HS 111, ECTN3 @ 95cm, ECTN16 @ 76cm and ECTN24 @ 30cm on facets under decomposing crust being my primary LOC. Similar results/structure were found at Copper on a NW aspect @ 8300', while S held less new snow due to earlier winds and more stout crusts/shallower pack.

The various facet/crust combinations at most elevation and aspects here have remained moist, particularly at Banner, which is positive in the long term but should be watched cautiously.

Avalanche Problems

New snow sluffed easily on a stout crust on solar aspects that held older snow, and any wind and settlement will craft stiffer slabs.

The crust/facet combinations that exist in the lower half of the pack on nearly every aspect and elevation have the potential to become more reactive, as witnessed by other activity in the forecast zones and other aspects off Copper.

Terrain Use

We skied 30-degree terrain and steered clear of wind-loaded or shallower N aspect zones, particularly nearing treeline and above 8500'.