Professional Observation - Blaine Mtn, Swan Range

Location Name: 
Professional Observation - Blaine Mtn, Swan Range
Observation date: 
Monday, February 19, 2018 - 20:30
Is this an Avalanche Observation: 
Yes
Observation made by: Professional Observer

Location

Tabs

Quick Observation

We rode into Doris Creek and the Jenny lake area today.  Riding conditions were outstanding, with minimal wind affect until approximately 6000-6500 ft.  Above that the wind had been ripping quite well and made for a dramatic looking landscape.  

  • We found a weak bond at the interface between the colder late storm snow and the denser early snow.  We found this on several aspects and at all elevetions until we got up into the windy areas.
  • Once in the alpine terrain we did have a wind slab fail with hard force (ECTP 22) 35 cm down.  
  • We had shallow shooting cracks (mostly 5-10 cm deep) on the wind loaded slopes.  
  • The Swan face was extremely wind scoured, and the ridgetops have enormous cornices built up right now.  
  • Snow amounts seemed to be roughly 12-16 inches on the lower roads and then increase to roughly 16-18 near the 6000 foot mark.  
  • We could see lots of evidence of recent avlanches from the last storm.  In the higher terrain we could see wind slabs that had peeled off and run 3/4 path.  In the sheltered terrain there was plenty evidence of storm slabs peeling off on almost every convexity.  Most of these were small, running less then 100 vertical feet.  
  • Above 6000 ft, in the sheltered North facing slopes we saw small surface hoar developing.
  • One deep slab ran off of the back side of Great Northern (SW'ly aspect)
Snowpack, Avalanche, Weather Images: 
Travel Details
Region: 
Swan Range - East Side (Hungry Horse Reservoir access)
Route Description: 

Doris Cr road to the end of the fireline and then we skinned to the ridgetop.

Activity: 
Snowboarding
Snowmobiling
Snowpack Details
Snowpack and Weather Details: 
Hide Terrain
Elevation of observation: 
5000-6500 ft
Above 6500 ft
Aspect(s) of observation: 
N
NE
E
SE
Red Flags: 
Shooting cracks
Persistent Weak Layers: 
On the surface
New Snow in the past 24 hours: 
0.00in.
Avalanche Details
Avalanche Details: 
Date and Time of Avalanche: 
Saturday, February 17, 2018 - 20:30
Avalanche Type: 
Soft Slab
Failure Plane/Weak Layer: 
Within storm snow
More information or comments about the avalanche: 

We saw evidence of recent avalanches within the storm snow.  These occured up to 6000 ft and were on all aspects.  Above that we saw wind slabs that had released in the steeper terrain.  They varied in depth from 10-20 inches deep and most running 500-800 vertical feet. 

Hide Trigger
Trigger: 
natural
Hide Terrain
Start Zone Slope Angle: 
35
Aspect: 
Northeast
Starting Elevation: 
near-treeline
Hide Size
Destructive Size: 
D1 Relatively harmless to people.
Relative Size: 
R1 Very Small
Crown Height: 
Less than 1 ft
Avalanche Length (Vertical Run): 
100ft.
Avalanche Width (Average width): 
30ft.
Avalanche Location: 
Date and Time of Avalanche: 
Saturday, February 17, 2018 - 22:15
Avalanche Type: 
Hard Slab
Failure Plane/Weak Layer: 
Old snow
More information or comments about the avalanche: 

Deep slab viewed from a distance on Great Northern

Hide Trigger
Trigger: 
natural
Hide Terrain
Aspect: 
Southwest
Starting Elevation: 
above-treeline
Hide Size
Destructive Size: 
D3.5
Relative Size: 
unknown
Avalanche Location: