Buried Surface Hoar - Scotts Lake

I skinned from Hope Valley to Scotts Lake to see how the past week of generally warm weather had affected our snowpack around 8,000 ft between Luther and Carson Passes. 

at 12:00 pm, I noted an air temperature of 7.5 degrees Celsius at 7,500 ft with snow conditions ranging from very firm and frozen in the shade/under trees to melting snow with 5-10 cm ski penetration in open and sun-exposed areas with Southerly aspects.  A 2cm breakable crust was found in some areas that receive partial shade throughout the day or were on more Northerly aspects. Light winds from various directions were accompanied by clear to broken skies.

I chose to dig a full profile on a NE aspect at around 8,100ft and just above Scotts Lake. I performed two column tests and recorded results of CT 29 and CT 26 both of which failed at 70cm down and Q1 on a layer of buried surface hoar.  I recorded a result of ECTX in my extended column test. Afterward, the extended column failed on the same layer as the CTs after I pried on it with my shovel. The layer of buried surface hoar was not 1cm thick, but I chose to call it a full layer in my profile due to the failures in my CT tests. It was quite difficult to determine a layer hardness. When trying to view the buried surface hoar by the naked eye, as well as under a loupe, the surface hoar appeared to have some rounded edges but maintained obvious striations. It was hard to tell whether the surface hoar was rounding because of metamorphic processes within the snowpack or because it was exposed to very warm air temperatures. 

The skiing back to the highway was quite variable.

Picture 1: Melting snow surfaces exposed to full sun with a view of the S face of Waterhouse peak

Picture 2: Breakable crust under my ski on a N aspect

Picture 3: Observation wall with a highlighted buried surface hoar layer

Picture 4: Pieces of buried surface hoar on the bottom of a slab that failed in a column test