Northwest Avalanche Center

Observation: Public

All Observations

Observation Details

Name:
Chelan County Mountain Rescue
Observation Date:
January 22, 2023
Submitted:
January 22, 2023
Zone or Region:
East Central
Activity:
Skiing/Snowboarding
Location:
Tronsen Ridge

Observed Avalanches

Did you observe any avalanches? 
Yes
Avalanche Type:
Soft Slab
Size:
Size 1: Relatively harmless to people
Elevation:
5300'
Aspect:
N
Comments:
We saw an ankle-biter of a skier-triggered D1 from last week's mid-week (18 Jan) storm. SS-AS-R1-D1. We saw a few larger crowns on northerly, steep ridgeline features above 40 degrees, but we didn't investigate the size or origin of these natural slides from around the MLK storms (SS-N-R1-D1?).

Signs of Unstable Snow

None reported

Observations

23 cars at the trailhead (1400) as several courses/large parties enjoyed the sunshine and clear sky conditions at Blewett Pass. Poor structure abounds in the Blewett Pass area, with a Dagwood sandwich of crusts and weak snows between the Christmas crust and the current snow surface (~10cm and 20cm down). Most notable are multiple buried surface hoar layers in the storm snow (16 Jan and 18 Jan) over the MLK crust. Below the MLK crust (3-4cm at 5700'), we found 1F snow over the 1/4 surface hoar/crust 30-40cm down. Large facets are present under this crust. Surface hoar is forming on sheltered slopes.

Media

Small skier-triggered storm slab in micro-terrain: SS-AS-R1-D1
Surface hoar on north around 5500'

Advanced Observations

Observed Avalanche Problem #1: 
Persistent Slab
Comments: 
Poor structure abounds in the Blewett Pass area, with a Dagwood sandwich of crusts and weak snows between the Christmas crust and the current snow surface (~8cm and 18cm down). Most notable are multiple buried surface hoar layers in the recent storm snow (16 Jan and 18 Jan) over the MLK crust (20-25 cm down). Below the MLK crust (3-4cm at 5700'), we found 1F snow over the 1/4 surface hoar/crust ~40cm down. Large facets are present under this crust. We had ECTN results on these multiple crust/facet layers, but no propagation (5400', N). This persistent problem isn't reactive under foot in this location.
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