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Observation: Days Fork

Observation Date
12/15/2018
Observer Name
Greg Gagne with Gunner Frey
Region
Salt Lake » Big Cottonwood Canyon » Days Fork
Location Name or Route
Days Fork
Weather
Sky
Clear
Wind Direction
West
Wind Speed
Light
Weather Comments
Generally light westerly winds, with moderate gusts (~20 mph) along ridges.
Snow Characteristics
Snow Surface Conditions
Dense Loose
Wind Crust
Melt-Freeze Crust
Damp
Snow Characteristics Comments
Widespread wind-affected snow surface from the increased winds later Friday evening. Crusts on southerly aspects, with even a few rollerballs on low elevation steeper slopes. Snow surface very supportable, with shallow 10 cm ski penetration.
HS below 10,000' ranges from 60-90 cms. From 10,000 - 10,500 depths are 120 cms.
Photo below is from top of Main Days looking over into Cardiac Ridge. These easterly aspects were especially skied hard on Friday, with several tracks. But westerly winds increased later Friday, and by this morning wind drifts and pillows had covered up all the tracks from the previous day.
Red Flags
Red Flags
Wind Loading
Poor Snowpack Structure
Avalanche Problem #1
Problem
Persistent Weak Layer
Trend
Decreasing Danger
Problem #1 Comments
Looking at east/southeast aspects ascending Chicken S&*t Ridge and in Days Draw and HS was shallower than I expected: 60-90 cms at most. On some quick pits I could find facets at the ground, but these had to be more east than southeast. Overall not an especially poorly-structured snowpack on these aspects below 10,000'.
Digging at 10,500 just below the top of Main Days was finding 120 cm snowpack, with 10 cms of basal facets at the ground. Some evidence of October crust, but it seems to have deteriorated in this area.
Avalanche Problem #2
Problem
Wind Drifted Snow
Problem #2 Comments
The wind slabs that formed overnight Friday were pencil-hard and 10-15 cms thick, but they were not responsive to ski cuts or any stability tests. Am thinking they will continue to settle out.
Comments
Overall very strong 1-meter slab on top of October facets where we were digging at the top of Main Days. Am thinking this strong slab is bridging the weak layers down near the ground, and it would be difficult to trigger a slide on these weak layers.
The zones that concern me are in thinner snowpack areas such as steep, rocky terrain where it would be possible to find a thinner, weak spot where the fracture would propagate.
Photo and corresponding profile of pit at 10,500' on NE aspect at 10,500' in Main Days. The layer between 10 and 90 cms quickly gains strength from a 4F to dense, 1F slab.
Today's Observed Danger Rating
Moderate
Tomorrows Estimated Danger Rating
Moderate