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PROFESSIONAL OBSERVATION FORM
 Start Date: 12.29.18 Name: Lundy, VandenBos Operation: SAC
 Drainage/Route:  Vienna Mine Observed Terrain:  7200-9600', SE-E-NE Zone/Region:  Smoky & Boulder Mountains
WEATHER OBSERVATIONS
 HN24: 1cm HST: Sky: OVC Precip: Temps:
 Ridgeline Wind: Moderate and Gusty from the NW
 Blowing Snow: L Snow Available for Transport: Small amounts
 Comments: It seemed that the forecasted snowfall occurred early this morning and did not continue through the day. We observed light wind transport at ridge level.
AVALANCHE OBSERVATIONS
 No. Location Date Size Type Trigger Aspect Elevation Comments
 Several Vienna Mine Cirque Older than a week N NE 9000-9500
 Comments: Evidence of several older avalanches, likely from mid December. Details were obscured by snowfall and wind since then, but they appeared to be D1-2 in size and ran in very steep, wind loaded terrain.
SNOWPACK OBSERVATIONS
 HS: 60-100cm at mid to upper elevations 
 Upper Pack: F to 4F, surface becoming slightly faceted. 
 Middle Pack: 4F to 1F, 12/11 SH 5mm observed at 9050', NE 
 Lower Pack: Upper elevation shady = 11/22 15-20cm 4F DH 3-5mm
Mid elevation solar = 12/11 20cm 4F FC 1-2mm 
AVALANCHE PROBLEM ASSESSMENT
Avalanche Characteristics
Character/Avalanche Problem:
Persistent Slab

Layer/Depth:
11/22 & 12/11, 40-90cm

Likelihood of Triggering
Sensitivity:
Stubborn

Spatial Distribution:
Widespread
Terrain
  Primary Concern Comments: 40cm depth is mid elevation solar ranging to 90cm on upper elevation shady
 Comments: 12/11 SH seemed unreactive. Small, fresh wind slabs observed at ridge level but were not reactive to stomping.
STABILITY TESTS
 Stability Test Results: 9050', NE: ECTX on both 11/22 DH and 12/11 SH. Cross slope PST 45/100end on 11/22 90cm down
8000, ESE: ECTN26 on 12/11 FC 40cm down
SNOW STABILITY
 Snow Stability Rating for your observed area: Confidence: Trend:
BOTTOM LINE
 Comments: The snowpack in the Vienna Mine area is similar to what I saw yesterday in the Sawtooths, except the basal weak layers seemed a tad bit stronger out Vienna (4F vs. F+). In our deeper snowpack areas like the western Smokies and Sawtooths, the problem is approaching deep slab in nature - at least on upper elevation shady slopes. There's a stout, 80+cm slab atop the 11/22 layer and I think you'd need a slope with some variable depth to impact the layer (i.e rocky and steep). The layer is showing slow signs of improvement in deeper snowpacks - but I'd still be leery of upper elevation, very steep, rocky, wind-affected slopes. I am less concerned with mid elevation, sheltered terrain terrain especially where the snowpack is relatively uniform.