Observation: NWAC Forecaster

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Basic Information

Observation Details

Observation Date:
December 12, 2022
Submitted:
December 12, 2022
Observer:
NWAC Forecaster - Katie Warren
Zone or Region:
East Central
Location:
Blewett Pass (4000ft-4800ft on primarily N aspects)

Signs of Unstable Snow

Recent Avalanches? 
None Observed
Cracking? 
None Experienced
Collapsing? 
Isolated

Media/Attachments

A very weak snowpack exists on sheltered north aspects near Blewett Pass. 
Moderately clean break from a shovel tilt test on a layer of buried surface hoar down under approximately 7 inches of recent snow. I suspect the smaller break about an inch towards the surface is the 12/9 new/old snow interface.
Buried surface hoar below about 7 inches of new snow. These feathery snow grains were mixed in with decomposing particles. 
These weak faceted grains near the bottom of the snowpack showed propagating and sudden test results.
While hard to see in this photo, these slopes showed textured surfaces from wind drifted snow. 

Advanced Information

Weather Summary

Cloud Cover:
Clear
Temperature:
25°F
Wind:
Calm
New/Recent Snowfall:
HST 18cm

It was a clear cold day with just a light breeze. Older wind-drifted surfaces were prevalent on exposed slopes higher in elevation.

Snowpack Observations

The snow surface was a mix of surface hoar and near surface facets. The storm snow had settled moderately but still lacked much of a cohesive slab structure. Overall I found a thin and very weak snowpack with boot penetration all they way to the ground.

I found 87cm of snow on a sheltered northern aspect at 4700ft. While walking through the meadow, I also experienced a small localized collapse.

I found buried surface hoar from 12/8 below the recent storm snow. It was mixed with decomposing particles but produced moderately planer breaks in shovel tilt tests that also highlighted the 12/9 old snow/new snow interface. The recent snow is very soft (F-) and lacks much for slab structure. Below the buried surface hoar is older storm snow increasing in density to the crust-facet combo from mid to late November (11/22 & 11/25). The crusts are beginning to break down, and it was hard to decern where the facets end and the crust begins.

Today's most notable observation was that stability tests produced sudden results (CTE3 SC, ECTP21 SC) on the 11/22 FC near the ground. We are monitoring this layer, and stability tests have continued to indicate propagation potential on these deeper layers.

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