Clear, occasional light variable winds, and cold!
Observation: Turnagain
Location: Tincan
Tincan to 3200′
Weather
Snow surface
A dusting of new snow overnight. Near treeline fragments of 5-10mm surface hoar was also on the surface - shiny! - see below.
Snowpack
Went out today to look at the Thanksgiving crust, seeking it out at different elevation bands while keeping the aspect/depth of the Thanksgiving crust layer - down 75-85cm in the pits - roughly the same. Probing in the vicinity of pits revealed that the crust was anywhere between 50 - 120 cm below the surface at and above treeline.
The only failure in a compression test was at the 1750' pit, where one of two regular compression tests failed in a sudden collapse with a 2cm drop of the block. No failures occurred in extended column tests, but some interesting propagating saw test results revealed that layers of facets on top of and below the upper Thanksgiving crust still have the ability to propagate if failure is initiated. See pit structure and full test results below!
The first pit, at 1750', had the "spiciest" test results, but the structure at this elevation band isn't as consistent as it is across the pit wall in the three pits below. The layer of facets below the crust had fairly large pockets of refrozen melt forms interspersed with loose facets.
This second pit, at the top of the Tincan Trees, found that the layer below the crust failed before the layer above the crust in PSTs.
This pit had PSTs failing at the same length for both above and below the crust, with a similar facet layer (size and hardness) in both... but as mentioned above, no results in compression tests
At this elevation the Thanksgiving crust is just one cm thick, and it's comprised of just one melt freeze layer. The facets below the crust were harder, showing signs of rounding. While the PST didn't fail until the saw was just 5cm from the end of the block, when it did fail the slab slid with speed despite a slope angle of only 32 degrees!
The saw is at the spot where the fracture propagated to the end of the block in the 2200' pit shown above.
Large fragments of surface hoar mixed with the dusting of new snow overnight, as the late morning sun started to come up at the 2200' pit!