Observation: NWAC Forecaster

All Observations

Basic Information

Observation Details

Observation Date:
December 9, 2022
Submitted:
December 9, 2022
Observer:
NWAC Forecaster - Matt Primomo
Zone or Region:
Stevens Pass
Location:
SPMR Backside and Lake Susan Jane

Signs of Unstable Snow

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

Media/Attachments

Walking beneath steeper terrain. This wasn't a problem given the conditions on this day.
West aspect at 4,700ft showing multiple weak snow layers. The thin drizzle crust is at 120cm, with a layer of surface hoar just below it.
Tilt test failure on a layer of buried surface hoar.
Fast shooting cracks where wind had stiffened some snow over a layer of buried surface hoar.
Underside of a block that fractured off just below a ridgeline. SE at 5,200ft. Surface hoar is clearly visible coating the interface.

Advanced Information

Weather Summary

Cloud Cover:
Obscured
Wind:
Calm
New/Recent Snowfall:
~6" yesterday, with a quick inch this morning.

Low clouds hung out around 5,000ft after a few broken hours in the morning. No blowing snow observed but only traveled up to NTL.

Snowpack Observations

More frequently than not, I could find buried surface hoar in the 2-5mm size down about 15-20cm. This layer would often fail with shovel tilt tests, switchback kicks, and hand shears. A very thin zipper 'freezing drizzle crust' usually marked the upper extent of this layer. In a few locations, small grained facets also appeared beneath this thin crust.

A couple locations that had some previously wind stiffened snow (1F) over weaker snow reacted with fast and clean fractures. See photo below of a block that clearly had a coating of surface hoar at the interface of one of these fractures from a SE aspect at 5,200ft below a ridgeline. Only very steep, open south facing slopes seemed to have much of a buried suncrust from 12/8.

Ski conditions were excellent with only isolated pockets of stiffer wind slab, mostly beneath the recent snow.

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