Close
PROFESSIONAL OBSERVATION FORM
 Start Date: 02.02.18 Name: Wieland Operation: SAC
 Drainage/Route:  Salmon River Headwaters Observed Terrain:  7300-9000 Zone/Region:  Smoky & Boulder Mountains
WEATHER OBSERVATIONS
 HN24: 3 HST: 3 Sky: BKN Precip: Temps: Above Freezing
 Ridgeline Wind: Light from the W
 Blowing Snow: Snow Available for Transport:
 Comments: Overcast skies in AM ->broken->scattered->
AVALANCHE OBSERVATIONS
 No. Location Date Size Type Trigger Aspect Elevation Comments
 1 Headwaters 1 N NW 8400
 Several Norton Today 1 Snowbikers triggered several near creek bottoms.
SNOWPACK OBSERVATIONS
 HS: 80-125cm 
 Upper Pack: Low elevation slopes had moist or slush surface by PM. 35-45cm's of surface snow was gaining strength and was now 4F slab over very weak FC, producing collapses on ascent. More wind loaded slopes were found above 8400' and also collapsing down ~50cm on fist hard FC. Naturals ran on thin layer of FC (1/5? 1/9?) above weak crust above 12/19.  
 Middle Pack: Found SH down 35 cm on NE slope @ 9000'. ECTN 17 and CTM 14 SC on this layer. The two avalanches I looked at ran on FC above weak crust and not the SH. Still not trusting either. 
 Lower Pack:  
AVALANCHE PROBLEM ASSESSMENT
Avalanche Characteristics
Character/Avalanche Problem:
Persistent Slab

Layer/Depth:
30-60cm

Likelihood of Triggering
Sensitivity:


Spatial Distribution:

Terrain
  Primary Concern Comments: Stubborn to reactive. Did not step into anything over 30°. Travelling near the tops of several steeper slopes only resulted in collapses.
 
Avalanche Characteristics
Character/Avalanche Problem:
Wind Slab

Layer/Depth:


Likelihood of Triggering
Sensitivity:


Spatial Distribution:

Terrain
  Problem 2 Comments: Most wind slabs were sitting on persistent grains. only got into middle elevation terrain where 1/30 wind affected slopes.
STABILITY TESTS
 Stability Test Results: See snowpack obs.
OBVIOUS SIGNS OF INSTABILITY
 Marked with checkmark if observed:
 Cracking (widespread) Depth: 30-50cm Length: 5m
 Collapsing (widespread) Depth: 30-50cm Length: 30m
SNOW STABILITY
 Snow Stability Rating for your observed area: Confidence: Trend:
BOTTOM LINE
 Comments: It was hypothesized that observed avalanches up here ran on SH, but looking at the larger one it ran on FC down 60cm. The other smaller slide was only slightly thinner, but likely failed on FC. Didn't check on smaller slide due to having to cross near a larger and wind affected slope.
FILE ATTACHMENTS

imagejpeg_0.jpg
Norton avalanche. Photo: Leeming

P1000276.jpg
Closer view of avalanche from 2/1/18 VandenBos ob.