Observation: White Pine

Observation Date
12/4/2018
Observer Name
Andrew McLean
Region
Salt Lake » Little Cottonwood Canyon » White Pine
Location Name or Route
White Pine - LCC
Red Flags
Red Flags
Collapsing
Poor Snowpack Structure
Avalanche Problem #1
Problem
Persistent Weak Layer
Trend
Same
Problem #1 Comments
We dug two pits, one N N/W and the other on a West face and both of them had the same 25cm of weak basal facets. With 100cm of new snow insulation on top of that and cold weather, it seems unlikely that this buried weak layer is going anywhere very soon.
Comments
Pit #1 - 9,424' N N/W, 30 degree slope. ECT results = 30 with no failure or propagation within the snowpack. Compression test = 11 on the basal facets. 120cm base
Pit #2 - 9,930' west facing 39 degree slope.
Basal facets were just as pronounced on north and west facing slopes at this altitude.
No sign of natural avalanche activity.
HUGE collapse at 9,400' on N N/W slope, but no fracture.
I think one of the bigger concerns for the upcoming days is that after a good dose of sun and clear skies today, the surface snow on the east. south and west slopes started to warm up, and with a good overnight freeze will become crusty, which will push powder seekers onto north facing slopes, which are the dangerous ones.
The top 100cm of snow seems very homogenous and well structured from fist penetration down to 4 fingers. There doesn't seem to be any weakness in this layer, which makes the snowpack kind of all or nothing - if it is going to go, it will go big. The danger in these upper elevation northish facing areas is still considerable, but elsewhere it is low.
Today's Observed Danger Rating
Considerable
Tomorrows Estimated Danger Rating
Considerable