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ADVANCED OBSERVATION FORM
 Start Date: 02.08.19
 Drainage/Route:  Greenhorn Observed Terrain:  N, 5800-6400 Zone/Region:  Wood River Valley
WEATHER OBSERVATIONS
 HN24: HST: Sky: OVC Precip: Temps:
 Ridgeline Wind:
 Blowing Snow: Snow Available for Transport:
AVALANCHE OBSERVATIONS
None Reported
SNOWPACK OBSERVATIONS
 HS: 93cm 
 Upper Pack: 22cm low density snow 
 Middle Pack: 3cm crust @71cm with small facets below. 1cm crust @63cm and decomposing crust @57cm. 1f slab 56-31cm 
 Lower Pack: 31-0cm. Fist hard larger grained facets 
AVALANCHE PROBLEM ASSESSMENT
Avalanche Characteristics
Character/Avalanche Problem:
Persistent Slab

Layer/Depth:


Likelihood of Triggering
Sensitivity:
Reactive

Spatial Distribution:

Where did you find this problem?
  Primary Concern Comments: 
STABILITY TESTS
 Stability Test Results: Pit in area where snowpack had collapsed. CT failed on isolation at 30cm from ground at what is likely the early January interface. Failure may have been because layer was already collapsed.
OBVIOUS SIGNS OF INSTABILITY
 Marked with checkmark if observed:
 Collapsing (isolated)    
 Comments: 2 large rumbling collapses @ ~6200ft. Crust in upper pack became weaker around this elevation and an intentional hop while skinning was able to collapse the weak interface in the lower pack. One collapse in 28° terrain propagated a crack 60-70ft up hill and 50ft wide.
SNOW STABILITY
 Snow Stability Rating for your observed area: Poor Confidence: MODERATE Trend: Steady
BOTTOM LINE
 Comments: Not easy to break through the crust @ lower elevations but as soon as you can the persistent slab seems to become touchy. If triggered, a slide would likely take the majority of the snowpack. With this first round of snow today I imagine that the snowpack will only be waiting for an outside trigger to produce a size 2 or larger slide.