Tahoe National Forest Sierra Avalanche Center

Pit dug to look at effects of melt water reaching the Feb 14 facet layer following two consecutive nights of poor refreeze conditions and record warm daytime temps.

Pit dug in below treeline terrain to examine old Feb 14 nsf layer.

Pit dug in open area below treeline to target old Feb 14 near surface facet layer.

Another ECT performed about 100 ft away in a slightly sunnier spot yielded ECTN results on the Feb 14th facets. Pit dug by Kevin Mecham.

Pit dug below treeline in a location with known Feb 14 facet layer. This layer is very isolated in a weak condition. A third ECT performed 20 feet away on the same slope scored ECTN-26 @ 162 cm.

Feb 14 facets are starting to clump when squeezed.

We did a loaded PST and a loaded CT. The load was 10cm of snow that we added to the surface and let it sit for 180 minutes. It was 1f in hardness by the time we did the tests. The tests failed at the base of our artificial slab on the current snow surface. In the loaded PST, we targeted the facet layer @ 179.5-175cm. The fracture started to propagate in that layer at a 22cm cut length then quickly stepped up to the interface between the current snow surface and the artificial slab.

Testpit dug to look at wind slab deposited on top of near surface facets. Pit dug in near treeline terrain. CT SC and ECTN results where the wind slab was 13 cm thick in initial pit. ECTP and PST results from where the wind slab was 19 cm thick as the pit expanded with additional tests.