Observation: Powder Mountain Backcountry

Observation Date
12/3/2018
Observer Name
Evelyn, Nichole, Butch
Region
Ogden
Location Name or Route
Powder Mountain backcountry
Weather
Sky
Overcast
Precipitation
Light Snowfall
Wind Speed
Calm
Weather Comments
Partly cloudy skies transitioned to overcast skies a bit before noon, with light to moderate lake effect snowfall. Cold.
Snow Characteristics
New Snow Depth
4"
New Snow Density
Low
Snow Surface Conditions
Powder
Snow Characteristics Comments
A few more inches of low density snow in the last 24 hours are icing on the cake.  They're sitting on mostly right side up snow that accumulated during the last 4 days.
Avalanche Problem #1
Problem
New Snow
Trend
Same
Problem #1 Comments
With so much new light density snow, I would expect sluffing on steep slopes. A few layers identified 30 and 40 cm down that failed with compression tests seem to be new snow instabilities, that should continue to strengthen. Though not in the forecast, if winds pick up there is lots of snow available for transport, and the danger could spike fast. Other thoughts for the future - the low density surface snow will be able to facet rapidly if we have cold, dry weather; and it will be worth keeping an eye on the shallower mid to lower elevation slopes for snowpack weakening.
Avalanche Problem #2
Problem
Persistent Weak Layer
Trend
Decreasing Danger
Problem #2 Comments
See comments below snow profile.
Snow Profile
Aspect
North
Elevation
8700
Slope Angle
30
Comments
Goal of the day was searching for old faceted pre-Thanksgiving snow.  Looked at two higher elevations, northerly facing slopes.  We found the facets, but the layer is very thin - maybe averaging 2 to 6 cm thick, up to 10 cm in a few places.  First two ECT tests in two different places - no fracture.  Third test, in the same pit as an ECTx - we got an ECT12.  There was no crust in the snowpack.
 
My overall feeling is on the high elevation, northerly facing slopes, the basal facet layer is so thin, that it's not continuous over the terrain, instead being broken by rocks and vegetation. I think there are only isolated places - above about 8500', northerly facing, with very smooth ground like rock slabs or grass - where you could connect a large enough area of the depth hoar for a slide to release.   Of note - we have few observations from the 9,000' to 9500' band in the Ogden area mountains, where the depth hoar could be a little more continuous.
Second snowpit profile above. Below, well developed, striated facets at the ground.
Today's Observed Danger Rating
Low
Tomorrows Estimated Danger Rating
Low

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