Seattle Ridge
Obvious Signs Of Instability
Recent avalanches-YES
Shooting Cracks-NO
Collapsing/whoompfing-YES, mostly localized
Avalanche activity:
Several small volume skier triggered pockets on steep rollovers @ ~1,800. (see
photo #1 and VIDEO) We were able to pull out small slabs in this steeper
terrain (>40 degrees)
1 small avalanche remotely triggered by another party from approximately 50 feet
away in steep terrain, over 45 degrees, SW aspect @ ~2,500’. (see photo #2) We
triggered the adjacent slope from 10 feet away. (see photo #3).
Average crown heights were 10-15”.
On average 15“/40cm of new snow above 2,000’.
Stability tests in multiple areas showed a general lack of a cohesive
slab and no propagation. Test results could have led you astray today.
Buried surface hoar was found in a sheltered location @ 2,500’ on an East facing
slope (see photo #4 and #5). The distribution of surface hoar is spotty and
difficult to pick out even in areas where it is present.
The distribution of the “drizzle crust”, formed between 12/6-12/8 is fairly
uniform between 1,000’-3,000’. All activity we observed today ran on this
crust. The weak interface between the new slab and the crust varied. In many
areas we observed light density new snow that was starting to decompose (as the
weak layer grain type). Surface hoar looks to be less of a culprit in the
bigger picture, but should not be ruled out as a potential weak layer.
The combination of light density snow, very little wind, and gradual
accumulation accounts for the initial character of this newest slab (not very
reactive). Settling of this new snow over time has helped to condense this snow
into slabs, as evidenced by today’s avalanche activity.
Shallow skier triggered soft slab @ ~1,800' E aspect
Remotely triggered soft slab @ 2,500' SW aspect (50 feet away)
Remotely triggered soft slab @ 2,500' SW aspect (10 feet away)
8mm buried surface hoar
Pit @ 2,500' NE aspect-obvious line in pit wall is surface hoar sitting on the 'drizzle crust'