Mild January days, cold clear nights and a shallow snow cover continue to stoke th facet machine. North facing slopes at mid-elevations in Rock Creek, Mammoth and the White Wing area are holding the 8-14 inches of snow wells but depths are so shallow, hittig rocks is a certainty. We visited the White Wing area and found about 18" on an open east-southeast facing slope. While many SE and E slopes are bare, this area may have been wind loaded from the north winds that stripped the Red Cone bowl as couple of weeks ago. Shaded NE facing slopes below treeline had less snowdepth and the snow lacked any cohesion- sugar snow.
As expected, the snowpack was faceted top to bottom with a 1 cm sun crust on the surface. Densities were higher and the snow was slab-like compared to the sugar textured snow found elsewhere in the area. There was a prominent low density layer of large facets 10 -11 inches down (see photo). A crack formed from collapse of the weak layer during compression tests but the block did not slide off the column. ECT’s tests showed collapse but no propagation. Compression tests are an effective test for crack initiation but do not provide any information on crack propagation; after all, we want information on whether a slope will avalanche on a weak layer.
Pit on ESE facing slope, 9,400 ft., 28 degrees. Low density layer is prominent at 10-11” down from the surface. There is a thin icy sun crust on top of the fist hardness facets. This layer represents the inch or two of snow that fell in mid-December. The slab on top is snow that fell from December 20-22- the higher density of this layer is the result of wind. CTM18,19 Q2 x4. ECTN18,21,22.
With a significant snow load, this weak layer could become more reactive and form a persistent weak layer. A few inches of new snow will only add another weak layer to the thin snowpack.