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Observation: White Pine

Observation Date
12/12/2013
Observer Name
Cam Mackenzie
Region
Salt Lake » Little Cottonwood Canyon » White Pine
Location Name or Route
Upper White Pine
Weather
Sky
Clear
Wind Direction
Northwest
Wind Speed
Light
Weather Comments
Beautiful day to be in the mountains. Chilly at white pine trailhead at 0800 but warmed rapidly once the sun got up high. Sun was definitely starting to get at the top of the snowpack in exposed locations.
Snow Characteristics
Snow Surface Conditions
Faceted Loose
Snow Characteristics Comments
Word of the day for was Touchy. Surface conditions were beginning to facet, giving excellent riding conditions. Between trailhead and 8500' there was beautiful surface hoar. Saw recent avalanching on all aspects above 10,000' leading us to play around in more mellow conditions. Collapsing and whoomphing on slopes, below 10 degrees. Stomped around on a decent size west facing test slope at 9600' or so and had an extraordinary collapse and shooting cracks out to 30' away both up-slope and down. Definitely wouldn't want to be on that if it were a steeper slope. Dug a pit in the same area. Results below.
Red Flags
Red Flags
Recent Avalanches
Cracking
Collapsing
Poor Snowpack Structure
Red Flags Comments
Multiple large whoomphs while breaking trail through meadows. Didn't check off rapid warming because although the sun was out strong, temperature profiles and hand pits through the day only showed if affecting the top 2-3cm
Avalanche Problem #1
Problem
New Snow
Trend
Same
Problem #1 Comments
Don't know what else needs to be said about this problem right now. Given a load/trigger, this layer has shown itself to be potent
Avalanche Problem #2
Problem
Wet Snow
Trend
Decreasing Danger
Problem #2 Comments
Soft slabs from last weeks storm seem to be less of an issue these days
Snow Profile
Aspect
Northwest
Elevation
9,500'
Slope Angle
24°
Comments
Snowpack structure wasn't great, however, it was better than I've been seeing in other locations. Using the "five lemons" the weak layer had 3: top 100cm of snow-pack, persistent grain type, and grain size difference of >1mm. The snowpack was very energetic with propagation and energy able to cross long distances easily. It wasn't taking much to get a failure and the weak layer was carrying energy well.
Video
We took a break mid morning and after seeing how well the weak layer was failure propagation, decided to see how wide of an ect it would fail across on a 20 degree (roughly) slope. Whether or not this is useful info could be debated but sometimes you have to have fun with it. First one was 200cm wide (the width of a bca ruler). Failed on tap 5 with a q1 quality shear.
Video
Second ect was 330cm wide. Same thing, failed on tap 4 clean across the column
Today's Observed Danger Rating
Considerable
Tomorrows Estimated Danger Rating
Considerable
Coordinates