Weak layer smorgasbord

CBAC 2020-21 Observations

Zone: Southeast Mountains

Location: Snodgrass

Date of Observation: 11/28/2020

Name: Zach Guy

Subject: Weak layer smorgasbord

Aspect: North, North East

Elevation: 9400′ – 11100′

Avalanches: Skier triggered several loose dry (facet sluffs) on steep, shaded aspects, D1 in size, entraining the upper half of the snowpack.
Investigated the reported skier triggered slab from yesterday. The slab was about 10 feet wide, 18″ thick, on a very steep, convex rock feature. It was a soft slab that appeared to fail on 1.5mm faceted grains on the ground. It entrained weak, faceted snow as it ran downhill. SS-ASc-R1-D1-O/G

Weather: Clear, calm winds, mild and inverted temps.

Snowpack: Widespread weak layer growth on all aspects and elevations! 2 to 4 mm surface hoar is developing on shady aspects up to about 10,000′, and pockety above that. Near-surface faceting in the recent snow is rampant on all aspects. The near surface facets are above a melt-freeze crust on SE-S-SW aspects. The entire snowpack is getting noticeably weaker in the past few days, becoming unsupportive and faceted throughout. We did not observe any signs of instability other than facet sluffing today. The current snowpack will become a problematic weak layer when/if we get a significant load.

 

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