Sawtooth Avalanche Center

Pro Field Report

Basic Information

Observation Details

Observation Date:
December 9, 2021
Submitted:
December 10, 2021
Observer:
SAC - VandenBos
Zone or Region:
Sawtooth and Western Smoky Mtns
Location:
Alturas Lake Creek Drainage (7,000-10,100')

Signs of Unstable Snow

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

Snow Stability

Stability Rating: 
Very Good
Confidence in Rating: 
Moderate
Stability Trend: 
Steady

Media/Attachments

https://www.instagram.com/tv/CXSfnsol_wA

Advanced Information

Weather Summary

Cloud Cover:
Partly Cloudy
Wind:
Light , NW
New/Recent Snowfall:
2-4cm

Clear skies over the valley with bands of clouds hanging over the Sawtooths and Western Smokys. Very brief periods of S-1 precip throughout the afternoon with no accumulation. 2-4cm of new snow overnight, total of 5-7cm in the past few days.

Snowpack Observations

HS=0-15cm at 7,000', 5-20cm at 7,500', 30-40cm at 8,000', 40-70cm at 8,5000'.
I continued my survey of middle and upper elevation shaded terrain with a visit to the Alturas Lake Creek drainage. The long drought has had its effect and the snowpack here is dominated by layers of crusts and facets. The weakest facets (4F to 4F-) are in the 10cm interval immediately beneath the razor crust that sits under the new snow. These (the weak pile of facets) are sitting on a 2-3cm thick melt-freeze crust (1F) that formed during periods of very warm ambient air temperatures. This combination of crust and facet is capable of producing avalanches when loaded, the only ingredient missing right now is the slab. There are several more pairs of crusts and facet stacks as you move down the snowpack. The facets in these intervals are less advanced and are retaining a bit more strength than the upper facets.

This snowpack is already messy and it is just going to get worse, identifying dates for individual layers is challenging. The nomenclature for the upper layers will be a little bit tricky. In some areas we've seen small amounts of snow on 12/6, 12/8, and 12/9. In other areas there hasn't been significant accumulation in the past days. Best bet will be to name the surface that is about to get buried by burial date. Who knows, maybe we get another nasty 12/11 this year...