Marion Lake obs

Location Name: 
Forecaster Observation - Essex Mountain, Flathead Range
Observation date: 
Sunday, December 24, 2017 - 13:15
Is this an Avalanche Observation: 
No
Observation made by: Forecaster

Tabs

Quick Observation

 

  • Pockets of surface hoar near ridgelines and small grained near surface facts forming at the surface.
  • Extensive avalanche activity from the 12/19 cycle. We traveled along Essex Mtn Ridgeline and nearly all paths on either side of the ridge had run, evidenced by visible crown lines, debris, and/or feeling the snow depth down to the Thanksgiving crust.
  • No signs of recent wind slab formation along this ridgeline. Calm winds and no blowing snow on the peaks.
  • No collapses or cracking on steep or low angle terrain. Minor sluffing on steep slopes. The snowpack structure is variable across steep terrain due to previous avalanches: anywhere from 6" over the Thanksgiving crust up to 30" over lingering facets above the crust. 
  • One pit in an area that hadn't avalanched had propagating, sudden collapse failure under moderate initiation, 90 cm deep on 4F- facets on the ground. ​
Snowpack, Avalanche, Weather Images: 
Travel Details
Region: 
Flathead Range - Bob Marshall Wilderness
Route Description: 

Up to Marion Lake and the NW side of Essex Mtn

Activity: 
Skiing
Snowpack Details
Snowpack and Weather Details: 
Hide Terrain
Elevation of observation: 
5000-6500 ft
Above 6500 ft
Aspect(s) of observation: 
N
NW
Persistent Weak Layers: 
On the surface
Buried
New Snow in the past 24 hours: 
0.00in.
Total Snow Depth: 
100-120 cm
Avalanche Details
Avalanche Details: 
Date and Time of Avalanche: 
Tuesday, December 19, 2017 - 18:15
Avalanche Type: 
Soft Slab
Failure Plane/Weak Layer: 
Old snow
More information or comments about the avalanche: 

All aspects and elevations. Up to at least D2.5 in size

Hide Trigger
Trigger: 
natural
Hide Size
Destructive Size: 
D2 Could bury, injure, or kill a person.
Relative Size: 
R3 Medium
Avalanche Location: