Pro Field Report

Basic Information

Observation Details

Observation Date:
December 30, 2020
Submitted:
December 30, 2020
Observer:
SAC - VandenBos (off duty)
Zone or Region:
Galena Summit and Eastern Mtns
Location:
Butterfield (6,800-9,700', primarily N-NE-E aspects)

Signs of Unstable Snow

Recent Avalanches? 
None Observed
Cracking? 
Widespread
Collapsing? 
Widespread

Advanced Information

Weather Summary

Cloud Cover:
Overcast
Wind:
Moderate , NW

Snowing S-1 off and on throughout tour (1130-300), with trace of total accumulation. Wind blowing steady at low end of moderate from NW on ridgelines, no snow being transported where I was.

Snowpack Observations

Dug on N-NE at 8,800'. Same old story, same old song. We might be tired of hearing it but it is not a good time to stop listening. Snow since 12/21 is F- to F. 12/13 (onset in this area) thru 12/20 snow is approaching 4F- at the base, but only if you are feeling generous. Wild to see such a soft slab continue to produce widespread collapsing. Handpits and pole probes reveal the same structure in all areas traveled.

HS=80cm
ECTP 2 down 35 cm (top of early-season facet stack)
CPST 17/100 END down 35cm
PST 18/100 END down 35cm

Continuing to expect the unexpected. At this point we've had plenty of forewarning that this snowpack will not behave well with a load. The pattern of natural activity is marching its way south, the slab is gradually building.

Avalanche Problems

Problem Location Distribution Sensitivity Size Comments
Persistent Slab
Isolated
Specific
Widespread
Unreactive
Stubborn
Reactive
Touchy
 Weak Layer(s): Dec 11, 2020 (FCsf)
Comments: Sensitivity somewhere between stubborn and reactive, but not sure it is that relevant with this sort of weak layer. When things get weird our classification systems based on "normal" conditions tend to fall apart. I'm basing personal decision making off structure and pattern of activity from past two weeks. I think weak layer was buried 12/13 here, but with pattern of loading I don't think we can unwind whether or not 12/11 and 12/13 interfaces are behaving differently.