Observation: 10420

Observation Date
12/18/2012
Observer Name
Keith Stebbings
Region
Salt Lake
Location Name or Route
10420 from Brighton
Weather
Sky
Overcast
Precipitation
Light Snowfall
Wind Direction
Southeast
Wind Speed
Light
Snow Characteristics
New Snow Depth
17"
New Snow Density
Low
Snow Surface Conditions
Powder
Snow Characteristics Comments
Overnight snow was light density staying in place for the most part due to decreasing winds overnight and today.
Red Flags
Red Flags
Wind Loading
Cracking
Poor Snowpack Structure
Red Flags Comments
Newest snow sluffing and ridgeline cracking were the prominent readily apparent issues in my travels.
Avalanche Problem #1
Problem
New Snow
Trend
Same
Problem #1 Comments
Video shows the PST still propagates and therefore a concern even though the column didn't slide off the weak layer. Spatial variability and elevation are key components to this weakness and I'm not trusting this persistent weak layer.
Avalanche Problem #2
Problem
Persistent Weak Layer
Trend
Same
Problem #2 Comments
NEW SNOW HAS HIDDEN RIDGELINE WIND SLABS FORMED DURING THE FEROCIOUS WINDS OF MONDAY.
Comments
10420 west ridgeline, N aspect, 9600'. Photo below shows a small cornice I released which produced a long running sluff in the new snow from last night down a steep narrow tree opening.
Green crystal card is below the fragile rain crust here at 9600', NNE aspect. Paintbrush is the old November facet layer. Results: PST full propagation at 30cm cut length below the crust but didn't slide off possibly because the slope angle was 34 degrees. An ECT at this same spot failed below the crust but did not progagate. Slab still not stiff enough to withstand taps but stiff enough to propagate without shock loading using the PST. Rain crust noted in my travels this week appears to end around 9800'. Is this what others are seeing? At this pit location (high elevation) the rain crust was more porous and therefore less of a barrier to vapor. I was seeing a less sugary and a thinner facet layer. I spent a bit of time on an E aspect at 10,200' not seeing a rain crust and getting a CT23Q2 on the interface between this storm cycle snow of the past 4 days and the old snow surface.
Video