Observation: Little Cottonwood Canyon

Observation Date
1/5/2020
Observer Name
Gagne
Region
Salt Lake » Little Cottonwood Canyon
Location Name or Route
Upper LCC/BCC Perimeter
Weather
Sky
Obscured
Precipitation
Heavy Snowfall
Wind Direction
West
Wind Speed
Moderate
Weather Comments
Periods of heavy, S1 snowfall and sustained moderate to strong westerly winds.
Snow Characteristics
New Snow Depth
3"
New Snow Density
Medium
Snow Surface Conditions
Powder
Wind Crust
Snow Characteristics Comments
About 5 cms new snow with some wind deposits. New snow was sluffing very easily on steep slopes.
Red Flags
Red Flags
Recent Avalanches
Poor Snowpack Structure
Red Flags Comments
Poor snowpack structure on southwest through southeast aspects.
Avalanche Problem #1
Problem
Wind Drifted Snow
Trend
Increasing Danger
Problem #1 Comments
Winds the past several days, into today and overnight Sunday into Monday have created pockets of sensitive wind slabs on a variety of aspects > 9500'
Avalanche Problem #2
Problem
New Snow
Trend
Increasing Danger
Problem #2 Comments
New snow was sluffing very easily on steep slopes. If amounts come in under-forecasted (< 10 cms/5") not that big an issue. But if we get more snow than forecasted, sluffing on steep slopes may be an issue in isolated terrain.
Comments
Spent time today looking at facet/crust combinations that have led to widespread avalanche activity on southwest through southeast aspects. Although this has been a very reactive weak layer with numerous remotely-triggered avalanches, overall the structure doesn't seem that alarming and I'm expecting it will stabilize fairly soon (within several days perhaps?) I dug several pits on these solar aspects > 9000' and could not get any ECTs to propagate. Shovel shear tests were getting STM (moderate pressure). The weakest snow is a layer of faceted snow on top of the upper-most crust, down ~30-45 cms (12-18").
Photo 1 is pit showing the different crust layers
Photo 2 is faceted grains around these crusts. Overall these are not very weak grains, they are rounded with some sintering (bonding) between the grains.
Photo 3 shows winds working snow well down off of ridgelines.
Hazard is Considerable in upper elevations that have received the most snow and wind. Mid elevations provide the best riding conditions as they are less affected from recent wind. Low elevations likely will remain at Low hazard.
Today's Observed Danger Rating
Considerable
Tomorrows Estimated Danger Rating
Considerable