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Professional Observation

Basic Information

Observation Details

Observation Date:
March 8, 2020
Submitted:
March 8, 2020
Observer:
SAC - Stefan (off duty) - Linnet
Zone or Region:
Galena Summit and Eastern Mtns
Location:
Central Boulders

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
None Experienced
Collapsing? 
None Experienced
See avalanche observations

Snow Stability

Stability Rating: 
Fair
Confidence in Rating: 
High
Stability Trend: 
Steady

Bottom Line

Thin, fresh windslabs have formed at upper elevation. These are sensitive to ski cuts and cornice drops, and where we were seem to mostly rest on a weathered, slick bed surface. Snow at low elevation was taking ambient heat in the afternoon, and refreeze was not deeper than 6"-8" in the morning.

Media

Small natural avalanches off the Cierro Ciento ridge in the Boulder mountains, E facing slope around 10800'
Small natural avalanches off the Cierro Ciento ridge in the Boulder mountains, E facing slope around 10800'

Advanced Information

Weather Summary

Cloud Cover:
Mostly Cloudy
Wind:
Light , SW

Cool temps in the morning, still snow on trees even at hwy level. Some S-1 squalls but no accumulation. Clearing late afternoon but solars took no heat. Ambient warming at lower elevs made new snow sticky and broke up crusts below approx 8000'

Avalanche Observations

 #  Date Location Size Type Bed Sfc Depth Trigger Comments Photo
1 Today Cierro Ciento area
N 10600 		D1 SS I-New/Old Interface 10cm AS-Skier
c-Intentional 		Ski cut triggered fresh wind slab around 4" thick, ran around 200' vert, about 60' wide. No propagation outside of ski cut. Debris piled up around 1-2' deep.
Small avalanche on N facing slope around 10600' in the Cierro Ciento area. Artificially triggered by ski cut, crown approx 4
several Past 24 hours Cierro Ciento area
E 10800' 		D1 SS N-Natural Several small naturals off the Cierro Ciento ridge. Could not get close enough to be certain, but would assume they ran on new/old interface. See gallery for one more image
Small natural avalanches off the Cierro Ciento ridge in the Boulder mountains, E facing slope around 10800'

Snowpack Observations

HN approx 3cm at hwy level, increasing to around 7cm at summit elevation.
Fresh slabs on upper elevation N and E about 10cm thick, not well bonded to old weathered surface. Mostly unconsolidated dust on crust on S, crust supportable down to 8000' in afternoon.

In the morning:
Some 10-15cm of moist/wet snow under 15cm supportable MFcr on lower elevation solars, dry facets under thin crust on shadies with some trapdoor in places

Avalanche Problems

Problem Location Distribution Sensitivity Size Comments
Wind Slab
Isolated
Specific
Widespread
Unreactive
Stubborn
Reactive
Touchy
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5
 Layer Depth/Date: 10cm, 3/7

Terrain Use

When we entered into avalanche terrain we stayed on small slopes with clean runouts and manageable consequences.

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