Huntington Ravine, reactive wind slab and scouring

By Ryan Matz | MWAC Forecaster

Date of Observation: January 4, 2019  11:00 AM
Location of Observation: Huntington Ravine, below northern gullies

Variable upper snowpack- Pockets and larger areas, particularly in Central, Pinnacle, and especially Odell, of recently formed wind with significant areas scoured to hard, supportable crust.
Wind slab was touchy though thin and small in observed locations, which were limited to the Fan and area below the Northern Gullies. Two key layers were observed in wind deposited snow above the crust, a slightly stiffer and cohesive layer over a slightly softer and less cohesive layer. This structure allowed hand shears to repeatedly fail on isolation. We expect this structure to be consistent for thicker, larger areas of wind slab where it would certainly be a concern.
Of note, it is difficult to visually discern the areas scoured to crust from the areas of wind slab. Differing angles, lighting, and of course proximity currently make a big difference in a person’s ability to identify areas of wind slab from the crust which is currently bright white.


ABOUT THESE OBSERVATIONS

Snowpack observations are one part of the complex puzzle which is your decision to enter avalanche terrain. Some observations may include stability tests. It’s important to understand that the results of a stability tests are seldom conclusive anywhere, but particularly in snow climates and terrain like ours where the primary driver of instabilities is wind drifted snow. Many stability tests exist and each works best with specific avalanche problem types. Stability test results should never be used alone as an indication that a slope or conditions are safe particularly when more obvious red flags are present. Please use this page as part of your information gathering process, but don’t make decisions based on a single piece of information. A good article that summarizes some of the issues associated with snow and avalanche observations can be found here.

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