East of WMR

We headed out today to investigate a large human-triggered avalanche that occurred near Spruce Park on 1/7.  The slide gave us the bullseye data we have been searching for over the past week; avalanches can fail on buried weak layers multiple feet deep, and can propagate widely. We were unable to reproduce unstable results in our test pits at and near the crown, highlighting the spatial variability of this weak layer.

We also found reactive but small wind slabs on lee slopes near ridge line that we were able to trigger intentionally.  The new snow was beginning to settle and slab up a bit towards the end of the day, though cracking in sheltered terrain was only isolated. The riding quality was excellent, and we kept a tight margin on our exposure and enjoyed the powder on low-angle slopes. 

Wind slab on exposed lee slope was reactive, but slab was soft and only about 4" deep. On sheltered slopes, cracking was isolated and only a few feet long. A human-triggered avalanche on a buried weak layer occurred yesterday.

The surface snow is largely right side up. About 35 cm above the 1/2 interface, and 50 cm or so over the Christmas Interface. Ski penetration is about 25-30 cm.

At the elevations of the large avalanche and our profiles, the Christmas Interface was ski, but not boot supportable, brittle, slick, and on the edge between a crust and a warm-up interface. 

Crown profile @ 6270 E 

• HS = 250cm
• ECTX
• Facets above the Christmas Interface were 2-3 mm and striated. 

Test Pit @ 6270 E (50' adjacent to the avalanche crown)

• HS = 230cm
• ECTX
• Rounding facets above Christmas Interface .5 mm

Test  Pit @ 6200 NNW

• HS = 230cm
• ECTN 24 down 35 cm on 1/2 Interface, ECTN26 down 50 on Christmas interface. 
• Rounding facets above Christmas interface .5 mm