Observation: White Pine

Observation Date
12/16/2020
Observer Name
Jeglum/Pavek
Region
Salt Lake » Little Cottonwood Canyon » White Pine
Location Name or Route
White Pine
Red Flags
Red Flags
Cracking
Collapsing
Poor Snowpack Structure
Avalanche Problem #1
Problem
Persistent Weak Layer
Trend
Increasing Danger
Problem #1 Comments
All you need to do is look at the Collins weather data for the last 5 weeks to know what we have going on in the basement. 5" of SWE then dry weather for weeks with Nov/Dec sun angles? Ugh. Today I would describe what we saw on N aspects above 9000' as something like a very slowly healing new snow instability. Propagation of cracks and collapsing were not widespread and the new snow since Saturday (settled to ~20 cm) was still forming only a very soft slab. We were debating whether ski cuts would still be an effective mitigation measure despite the weakness technically being a PWL. But new snow instabilities heal in a matter of hours to maybe a couple days. This will be around for a long time. I expect that with the warmth, clouds, wind, and precipitation tomorrow this observation will be quickly irrelevant.
Comments
With the moist NW winds today it was clear that N aspects up high got some rime. A very thin rime crust was observed on the snow surface on a NW facing (but not particularly exposed) slope at 10k. Sun got to the new snow on west aspects as high as 10k as well. My phone died so unfortunately I took no pictures.
Today's Observed Danger Rating
Moderate
Tomorrows Estimated Danger Rating
Considerable