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Professional Observation

Basic Information

Observation Details

Observation Date:
December 18, 2020 - December 18, 2020
Submitted:
December 18, 2020
Observer:
TAC - Steve Gately
Zone or Region:
Taos Area
Location:
Bull of the Woods

Signs of Unstable Snow

Recent Avalanches? 
None Observed
Cracking? 
Isolated
Collapsing? 
Isolated

Snow Stability

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

Bottom Line

Moderate to strong winds over the last 48hrs have stiffened slabs mainly on North through East aspects above tree line. We were finding 2 to 3 foot pencil hard slabs over weak snow, in part due to wind deposition. This exact structure was not widespread but evidence of stiffening slabs from strong winds was widespread. Slab stiffening was also observed near tree line as well, just not as substantial. Below tree line much of the snowpack is faceting again and is on it's way towards becoming cohesion-less given enough time. The one exception here is the upper end of below tree line terrain. You can still find areas, typically in open terrain, that have enough of a slab present to still collapse underfoot and present a concern for avalanches.

Media

Softer slabs exist the further you descend in elevation. This profile taken on an East aspect near tree line had a 1 to 2 foot F-4F slab over 2-3mm depth hoar.
Example of a small isolated pocket of wind slab that we were able to release from the ridgeline. Notice that this slab failed within the transported snow and not on a buried weak layer of facets. This is an important distinction.
Snow profile for a Northeast aspect above tree line. An obvious strong over weak concern is illustrated.

Advanced Information

Weather Summary

Cloud Cover:
Mostly Cloudy
Temperature:
14
Wind:
Moderate , W

Cold day out there today with temperatures 10 degrees or more below where they were 24hrs ago. Wind was blowing moderately out of the West. Where we traveled we didn't observe wind actively transporting snow - however, we saw plenty of evidence of where it did over the previous 24hrs.

Snowpack Observations

Hard slabs are forming on our above tree line terrain from strong Westerly winds over the past 48hrs. Shallower snowpack's that can be found both near and below tree line have softer slabs that are deteriorating, especially in wind sheltered areas. Depth Hoar is the main layer of concern here. In deeper snowpack's near and above tree line you can find a layer of near surface facets buried just under our most recent storm snow.

Small pockets of isolated wind slab have formed on the leeward sides of ridgelines and gullies. These avalanches if triggered would be small. The more likely scenario is that areas of heavy wind loading would fail on facets creating a larger persistent slab avalanche.

Snow profile for a Northeast aspect above tree line. An obvious strong over weak concern is illustrated.
Softer slabs exist the further you descend in elevation. This profile taken on an East aspect near tree line had a 1 to 2 foot F-4F slab over 2-3mm depth hoar.

Avalanche Problems

Problem Location Distribution Sensitivity Size Comments
Persistent Slab
Isolated
Specific
Widespread
Unreactive
Stubborn
Reactive
Touchy
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5

Terrain Use

We surveyed almost all of our terrain from the safety of the ridgeline today.

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