Observation Date
1/12/2017
Observer Name
Greg Gagne with Dave Pease & Bob Frey
Region
Salt Lake » Big Cottonwood Canyon » Mineral Fork
Location Name or Route
Mineral Fork
Weather
Sky
Overcast
Precipitation
Light Snowfall
Snow Characteristics
New Snow Depth
6"
New Snow Density
High
Snow Surface Conditions
Powder
Snow Characteristics Comments

Recent snowfall is dense and spongy with a mixture of graupel and rimed stellars. Shallow ski pens (10-15 cms) and very supportable. No cracking or collapsing.

Was finding graupel pooled below steeper cliff bands.

Red Flags
Red Flags
Recent Avalanches
Heavy Snowfall
Wind Loading
Comments

Did not get into wind-affected terrain, so instead will focus on two things I was looking at today:

1. Two weak layers now buried down 50-75 cms. A layer of graupel as well as a weaker layer containing a density change/facets.

On Tuesday I was getting full propagation on a density change (with some possible faceting) at 9200' in two different drainages in Big Cottonwood Canyon (Days Fork and 10,420'). This layer was down 35 cms (~1') Scores were identical: ECTP12 Q1 in three different pits.

Was finding the same structure today at 9200' on a NE aspect in Mineral Fork. This layer is now down 60 cms (2'). Still full propagation, but much higher score as well as lower quality shears: ECTP25 Q2

​There is spatial variability, but I also think this layer is not especially weak and will continue to strengthen.

Two photos contrast the pits from Tuesday and today.

​2. Crust/facet layering at low and mid elevations. Evelyn pointed this out in today's forecast, and there is quite a bit of variability in its distribution. Trent has also done a very nice job of highlighting these layers in Mineral Fork.

Dug several quick pits at 7700' today and could easily find the different rain crust layers. The most concerning layer was a rain crust down about 45-60 cms (18-24") with weak, faceted snow underneath the crust. The recent rain and warm temperatures saturated the snowpack at this elevation, and I was finding damp/moist grains. Varying stability results however: In one pit could not isolate a column as it failed on the facets underneath the crust. Another pit I could not get any failures. A third pit got a clean shear at the faceted layer below the crust at 12 taps (CT12).

I am expecting that these layers will continue to heal (hopefully freeze up) and adjust to the recent load. Where I was looking today there also wasn't much of a load on these layers. However, this same layer was active in avalanches on Wednesday (Logan Canyon), so is likely more of a concern where there is a greater load.

Overall the hazard at the lower and mid elevations is trending towards Moderate in the Cottonwoods. I was not able to evaluate upper elevation aspects that received wind loading from the recent strong winds.

Today's Observed Danger Rating
Considerable
Tomorrows Estimated Danger Rating
Moderate