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Observation Date
12/15/2012
Observer Name
Cawley
Region
Salt Lake
Location Name or Route
Upper LCC
Weather
Sky
Obscured
Precipitation
Light Snowfall
Wind Direction
Southwest
Wind Speed
Calm
Weather Comments
Winds were light throughout the day, although a brief period of moderate winds in the afternoon was enough to tie things together along the ridgelines on SE-E-NE facing slopes, creating sensitive soft slabs in the top 3 inches of the overnight snow.
Snow Characteristics
New Snow Depth
10"
New Snow Density
Low
Snow Surface Conditions
Powder
Snow Characteristics Comments
New snow is barely there, and runs down the slope with minimal provocation. This characteristic is enhanced by the 1F-pencil hard wind slab/rain crust on nearly all aspects in exposed terrain. In our exit on S-facing Superior today @4pm, we noted one very long running slough in particular, which seemed to have run much earlier in the day, to about halfway down the lower apron of Superior, leaving significant debris.
Red Flags
Red Flags
Poor Snowpack Structure
Red Flags Comments
Instabilities associated with the early december "climate change" crusts(s) are not as glaring in the exposed, high elevation terrain of upper Little Cottonwood Canyon, although recent cornice drop-triggered avalanches along the Cottonwood Divide in Cardiff and Days demonstrate that with rapid loading, failure in the midpack crust/facet cheesesteak or to the basal depth hoar is likely. Still, no significant cracking or collapsing noted in extensive travel in steep terrain, on all aspects, on and near the Cottonwood Divide in upper LCC today.
Avalanche Problem #1
Problem
New Snow
Trend
Increasing Danger
Problem #1 Comments
Although we clearly have a ~deepslab cycle eminent throughout the Wasatch with the approach of several windy, snowy days, my take-away from the last two days of skiing is how hard the old snow surface became during the various wind events of 12/10-12/12, without the aid of a significant period of strong sunshine, on nearly all aspects. Even in sheltered locations such as the "Eyebrow" in Cardiff Fork and in the Point Supreme/Rocky Point area, the old snow surface in ridge-line starting zones is supportable to skis and even to ski boots in many places. With how un-molested today's light density new snow remains in this terrain following a windless day, I suspect it will become a perfect weakness atop a perfect bed surface of hard slab in much of our upper elevation terrain, and that at least above 9500' in deeper snowpack areas, starting zones may avalanche before they are able to accumulate a load of new snow sufficient to collapse the well-advertised early december raincrust/facet weaknesses.
Avalanche Problem #2
Problem
Persistent Weak Layer
Trend
Increasing Danger
Problem #2 Comments
Snowpits in more sheltered locations indicate an obvious weakness in the rain-crust/facet situation. It will be interesting to see whether slopes that feature widespread wind-loading from 12/12 are the first to go because of the additional load already present, or if the thinner snowpack of the mid-elevations is more susceptible to the incoming powder-party.