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PROFESSIONAL OBSERVATION FORM
 Start Date: 02.19.17 Name: Davis, Linnet Operation: SAC
 Drainage/Route:  Etna Observed Terrain:  5,600-8,200, W-N Zone/Region:  Wood River Valley
WEATHER OBSERVATIONS
 HN24: 22 cm HST: 45 cm Sky: SCT Precip: S3 Temps:
 Ridgeline Wind: Moderate and Gusty from the SW
 Blowing Snow: M Snow Available for Transport: Small amounts
 Comments: Waves of sun and whiteout. Intermittent periods of S3 strong wind and intense snow transport from the south and southwest. Accumulations of ~1 inch during the tour. Most of our time spent in exposed middle elevations we experienced moderate west wind and light to moderate snow transport.
AVALANCHE OBSERVATIONS
 No. Location Date Size Type Trigger Aspect Elevation Comments
 Comments: No new avalanches observed.
SNOWPACK OBSERVATIONS
 HS: n/o 
 Upper Pack: Norths: HST 15-45 cm heavy powder on 1-3 different crusts near the (2/16) interface. Wests: 5-25 cm settled creamy new snow atop soft rain crust.  
 Middle Pack:  
 Lower Pack:  
AVALANCHE PROBLEM ASSESSMENT
Avalanche Characteristics
Character/Avalanche Problem:
Wind Slab

Layer/Depth:
20-60 cm

Likelihood of Triggering
Sensitivity:
Stubborn

Spatial Distribution:
Specific
Terrain
  Primary Concern Comments: Some isolated cracking.
 
Avalanche Characteristics
Character/Avalanche Problem:
Persistent Slab

Layer/Depth:
45 cm

Likelihood of Triggering
Sensitivity:
Touchy

Spatial Distribution:
Isolated
Terrain
  Problem 2 Comments: Some cracking and collapsing. Maybe narrow elevation band.
STABILITY TESTS
 Stability Test Results: No results on western aspects. Heavy settled powder glued to a crust. Norths produced easy shears down 22 cm below last nights snow. Propagating results in facets atop a crust below that down 45 cm: ECTP 16, 19 on FC 1 mm
OBVIOUS SIGNS OF INSTABILITY
 Marked with checkmark if observed:
 Cracking (isolated)    
 Collapsing (isolated)    
 Comments: Localized cracking and collapsing on middle elevation norths and wind-affected terrain in shallow wind slabs.
SNOW STABILITY
 Snow Stability Rating for your observed area: Good Confidence: LOW Trend: Improving
BOTTOM LINE
 Comments: This storm and warm temps have the feel of short-lived spikes in instability followed by rapid healing. Norths were the exception today with some propagating results in 1 mm facets on a buried crust. This crust was the uppermost of three within a 20 cm layer. Unsure when this formed (fluctuation in rain line or warm temps Friday?). Maybe this will only be a problem in a narrow elevation band. Felt comfortable skiing steep wests. Would have been more hesitant in any wind-loaded pockets on norths due to uncertainty in the bond near the (2/16) interface.