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Observation Date
12/8/2012
Observer Name
Greg Gagne
Region
Salt Lake
Location Name or Route
Silver Fork
Weather
Sky
Obscured
Precipitation
Moderate Snowfall
Wind Direction
Northwest
Wind Speed
Moderate
Weather Comments
Temps were -9C and dropping. Where I was, winds never got into the Strong category.
Snow Characteristics
New Snow Depth
6"
New Snow Density
Low
Snow Surface Conditions
Powder
Snow Characteristics Comments
Super-light density. Mostly S1 snowfall, though there did seem to be a spike around 11 am and I was noticing some sensitivity in the new snow. 15 - 20 cms (6-8") new in wind-sheltered terrain at 10000' when we were skiing out at noon. HS on a north-facing slope at 10000' was 110 cms.
Avalanche Problem #1
Problem
New Snow
Trend
Same
Problem #1 Comments
The buried November facets likely remain our overall concern. Today I was getting compression test scores in the low 20s (CT 21 was lowest score) fracturing on this layer which was buried approximately 30 cms (1') down. Q2/RP. However, over the past 6-8 days I (and several others) have been noticing this layer strengthening, so I am suspecting this layer won't be as problematic as originally thought. No collapsing at all.
Avalanche Problem #2
Problem
New Snow
Trend
Decreasing Danger
Problem #2 Comments
At times it was snowing pretty hard during our early morning tour and the new snow was becoming more sensitive during a spike in precip late morning. These instabilities typically heal very quickly (sometimes a matter of hours) and are easily managed with ski cuts. However, I was also getting the new snow to fail at its interface with a rain crust on north aspects between about 9000'-9500'. Quick observations showed some faceted snow atop the crusts providing the weak layer. These were very soft, new snow avalanches that were not propagating much more than a meter from my skis, yet on steeper aspects the sluffs could contain a fair volume of snow. Again, a manageable hazard.
Comments
A somewhat complicated snowpack on northwest through northeast aspects. Approached Silver Fork from Solitude and noticed the transition from very thick rain crusts at lower elevations to thinning crusts up to about 9500'. Where there are crusts, they are forming facet sandwiches that are fracturing at 15-20 taps. At upper elevations (> 10000') where I am not finding crusts there are still the buried November facets which are now buried approximately 30 cms down. There are also a variety of 1F layers of wind deposits as well. There is still not a load significant enough to stress any buried weak layers, and the very light density new snow is probably not adding much water weight to the snowpack. Have been doing alot of ski pole penetrations (flip the pole upside down and jam the handle down into the snowpack) as it is a quick way to get alot of information about buried weak layers. I did not observe any widespread wind loading apart from some drifts along the ridgelines, yet I imagine there is some wind loading on leeward aspects from the NW winds at higher elevations. My immediate concern would be fresh wind loading. Overall a Moderate danger. Super good skiing - Saturday was BDOY.