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Observation: Powder Park

Observation Date
1/11/2014
Observer Name
J. Spitzer, M. Primomo/AIARE 2
Region
Salt Lake » Big Cottonwood Canyon » Mill D North » Powder Park
Location Name or Route
Mill D North, Powder Park 3
Weather
Sky
Overcast
Wind Direction
Southwest
Wind Speed
Light
Weather Comments
Thin high clouds in AM changing to overcast by midday. Winds speed calm in valley bottom and light out of the SW at 9K ridgelines. Wind speed increased as the day progressed.
Snow Characteristics
New Snow Depth
14"
New Snow Density
Medium
Snow Surface Conditions
Rain-Rime Crust
Snow Characteristics Comments

Traveling up Mill D North we observed a thin, hard, smooth, and translucent crust coating the surface of the snowpack. As sited below from a research paper by Karl Klassen on the difference between Rime and Freezing Drizzle (<0.5mm water droplets) Crust.

The characteristics of the crust that forms vary depending on the atmospheric and snow surface conditions that exist as the crust forms. Classically, however:

- Hard rime crusts are milky-white and kind of crunchy. - Soft rime crusts are milky-white and more feathery. - Freezing rain/drizzle crusts are hard, relatively smooth, and clear.

"http://www.aspenexpeditions.com/blog/2012/02/03/crusty-crusts-how-myster...

Red Flags
Red Flags
Recent Avalanches
Cracking
Rapid Warming
Poor Snowpack Structure
Avalanche Problem #1
Problem
Persistent Weak Layer
Problem #1 Comments

Found the most problematic layer to be 70-80cm down from the surface on NW-N aspects between 8600 and 8800ft in the Milll D North area. These were 2mm facets covered on December 3.

This layer gave us variable test results with a number of tests performed:

Compression Test (CTM to H BRK, SC), and Extended Column Test (ECTN to P 25-30).

However, our results with the Propagation Saw Test proved much more uniform, and a better indication of the instability (PST 30 to 35/100 (End)). This shows us that once initiated, a fracture is likely to propagate.

With more loading, this layer we can expect this layer to become more reactive.

Avalanche Problem #2
Problem
Persistent Weak Layer
Problem #2 Comments

Associated with terrain features at and near ridgeline. We observed a recent Wind Slab avalanche (D2) off the North side of Desolation Ridge.

Comments

Drizzle Crust from 8,600ft on North aspect in Mill D North.

Drizzle Crust from 8,400ft on SW aspect in Mill D North

Video

Video of a PST from 8,800ft on a NW aspect in Powder Park 3. PST 30/100 (End)

Today's Observed Danger Rating
Considerable
Tomorrows Estimated Danger Rating
None