Observation: Mill B South

Observation Date
Observer Name
Salt Lake » Big Cottonwood Canyon » Mill B South
Location Name or Route
Mill B South
Weather Comments
Light flurries until 0900 then clear and cold. Afternoon provided an inversion layer around 9000'
Snow Characteristics
Snow Surface Conditions
Faceted Loose
Wind Crust
Snow Characteristics Comments
Travel was 210-->Monte Cristo--> Mill B So.--> Broads.
3 different surface conditions have my attention:
1) Pockets of cohesive wind crust- Most exposed terrain above in upper drainages >9000 feet has evidence of wind from this last week. This has created spatial variability, with everything from thin skin topped with surface hoar to 4cm pencil-hard with the board with facets maturing underneath. In steep terrain this could lead to a small but consequential ride and it's difficult to tease out where these small slabs will be reactive and cohesive enough to create an issue with more snow on top. The temperature gradient continues to promote faceting underneath this crust.
2) Continuous surface hoar in sheltered areas- Whether on top of wind slab or just soft snow, areas of preserved hoar have potential to become the future persistent weak layer. As the next snow approaches it's important to keep in mind where this SH (some of it 5-8mm) still lie in tact.
3) Near-surface faceting- Many locations in these drainages have the top 10-15cm quite faceted and the layer is a continuous, weak (F to F-) interface for the next storm. Some locations with thinner snowpack and rocky terrain are weak and faceted to near the ground.
All 3 of these conditions can promote wide, easily-triggered slab propagation whenever we see snow again.
Otherwise, I'm still seeing widespread evidence of the November 9 natural cycle, characteristically similar to what observers/ski patrols have reported for the last week. In these drainages that looked like fractures on lee sides (N-through-E) of alpine ridges just under cliff bands on the storm slab interface.
Pic 1 & 3 are upper cirque locations just under the LCC/BCC ridge.
Pic 2 draws out wide areas that are peppered with fractures.
Red Flags
Red Flags
Poor Snowpack Structure
Today's Observed Danger Rating
Tomorrows Estimated Danger Rating