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Observation: Mill B South

Observation Date
2/16/2016
Observer Name
Dana Holmes
Region
Salt Lake » Big Cottonwood Canyon » Mill B South
Location Name or Route
Uppper Mill B South
Weather
Sky
Scattered
Wind Direction
Southwest
Wind Speed
Light
Weather Comments
Light winds from the SW with some stronger gusts on the higher ridges.
Snow Characteristics
Snow Surface Conditions
Rain-Rime Crust
Damp
Snow Characteristics Comments
Sorry for the text-only obs, no camera today. We were surprised to find what appeared to be a very thin rime crust on all aspects right up to 10,000+ feet. It wasn't thick enough to make the riding conditions terrible, just a bit strange. The crust was starting to wet out and soften on sunny aspects by midday. Riding conditions were passable down to about 7800 feet where things got pretty ugly with a thick punchy breakable melt freeze crust on all aspects; rapidly softening in sunny areas.
Red Flags
Red Flags
Wind Loading
Collapsing
Rapid Warming
Poor Snowpack Structure
Red Flags Comments
Skinned up to around 10,500' in low-mid angle somewhat wind sheltered terrain with a predominantly NW facing aspect. The rime crust severely limited the amount of snow available for transport and we observed almost no active loading taking place - we didn't find any new drifts from today sitting on top of this crust, only drifts from yesterday underneath it. <!--break--> The rime crust made it difficult to visually identify loaded areas from yesterday, but pole probing revealed stiff 4-6" wind slabs on cross loaded terrain features sitting on melt freeze crust or small grained faceted snow from last week, depending on micro-aspect. These crusted over drifts and shallow slabs from yesterday seemed very stiff and stubborn. Jumping on small rollovers didn't produce any results. <!--break--> Had a loud collapse on lap #2 in E/NE facing terrain "Sidewinder" skinning towards the ridge as the slope angle increased to low 30s - approximately 9800'. Culprit weak layer was faceted snow that formed in this sheltered area below a cliff band during last week's high pressure.
Avalanche Problem #1
Problem
Wind Drifted Snow
Trend
Decreasing Danger
Problem #1 Comments
As mentioned earlier these wind slabs seemed quite stubborn anywhere we prodded them, but there was a huge variability in what they were sitting on for old snow surface. The collapse we felt suggests to me that in the right spot you could remote trigger one. Probably not deep enough to bury you, but enough to seriously ruin your day if you were in compromising terrain.
Avalanche Problem #2
Problem
Wet Snow
Trend
Same
Problem #2 Comments
Crust and underlying new snow was starting to wet out on sunny aspects by midday so I would expect to see some wet slabs running on last week's melt freeze crust this afternoon and tomorrow afternoon at mid elevations.
Today's Observed Danger Rating
Moderate
Tomorrows Estimated Danger Rating
Moderate
Coordinates