Observation: Public
Observation Details
Name:
Baker Mountain GuidesObservation Date:
January 27, 2021Submitted:
January 27, 2021Zone or Region:
West NorthActivity:
Skiing/SnowboardingLocation:
North Twin SisterTriggered Avalanches
Did you trigger any avalanches?
YesWas it intentional?
NoAvalanche Type:
Soft SlabSize:
Size 1: Relatively harmless to peopleElevation:
Near TreelineAspect:
NEComments:
Both avalanches we triggered today broke roughly 12-18in deep and ran atop a crust layer capping a series of crust/facet layers from the last few weeks of high pressure. One avalanche was remotely triggered from about 20ft upslope.Photo:
Signs of Unstable Snow
Did you see shooting cracks?
Yes, IsolatedDid you experience collapsing or whumpfing?
Yes, WidespreadObservations
Our group triggered two small (D1) avalanches while touring in the basins to the North of the North Twin Sister. The first was a soft slab triggered on our first run of the day on a small, subtle convex roll greater than 35 degrees and likely ran on a layer of small facets capping a crust/facet sandwich structure from our period of high pressure over the past few weeks. We toured to the East and began experience widespread collapsing as we travelled. We also observed cracking (see photo) where the wind drifted snow into larger and denser slabs. In general, we found 4-5in of more dense snow that fell overnight overtop another 3-4in of less dense snow from Monday/Tuesday sitting atop the crust/facet sandwich structure. While descending on our second run, one member of the group remotely triggered a small (D1) avalanche from roughly 20 ft upslope while approaching a small wind loaded gully on a convex roll greater than 35 degrees. This avalanche also ran on the uppermost crust of the crust/facet sandwich. We believe that the collapsing we experienced was occurring within the crust/facet sandwich, while both avalanches ran on the uppermost crust layer. Both avalanches occured within the Near Treeline elevation band
Media
