Sensitive wind slabs above Skiumah Lake

Location Name: 
Forecaster Observation - Skiumah Lake, Flathead Range
Observation date: 
Tuesday, March 27, 2018 - 13:45

Is this an Avalanche Observation: 
Yes
Observation made by: Forecaster

Location

Tabs

Quick Observation

We climbed above Skiumah Lake to monitor for wind slab formation.  We found thicker drifts extending further down in elevation than expected.

  • 1" to 2" of new snow accumulated mid-day above 5,000'
  • Strong to extreme wind gusts with intense blowing snow above the lake
  • We found drifts up to 2 feet thick, generally 4" to 8" thick on average on cross-loaded terrain features above 5,000'.  Drifts readily produced shooting cracks and small collapses.
  • We intentionally triggered several wind slabs, D1 in size, at mid elevations. Slides were breaking at or just above the most recent rain crust.
  • We could easily identify and avoid drifted areas by textural clues, feeling deeper drifts, and a color distinction between the bluish wind scoured rain crust and white wind drifts. We chose to avoid wind loaded terrain in bigger or more consequential terrain features. 
  • The freezing level was ~4,500'.  Below that, the snowpack was saturated and unfrozen, but appeared to be unreactive to wet avalanche concerns.
Snowpack, Avalanche, Weather Images: 
Snowpack, Avalanche, Weather Videos: 

March 27, 2018. Sensitive wind slabs in the Flathead Range

Travel Details
Region: 
Flathead Range - Middle Fork Corridor
Route Description: 

Above Skiumah Lake to 5500

Activity: 
Skiing
Snowpack Details
Snowpack and Weather Details: 
Hide Terrain
Elevation of observation: 
3500-5000 ft
5000-6500 ft
Aspect(s) of observation: 
N
NE
Red Flags: 
Shooting cracks
Collapsing / whumpfing noises
Blowing snow
New Snow in the past 24 hours: 
2.00in.
Avalanche Details
Avalanche Details: 
Date and Time of Avalanche: 
Tuesday, March 27, 2018 - 12:45
Avalanche Type: 
Soft Slab
Failure Plane/Weak Layer: 
Within storm snow
Hide Trigger
Trigger: 
skier
Trigger Modifier: 
Intentionally Triggered
Hide Terrain
Aspect: 
North
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): 
40ft.
Avalanche Width (Average width): 
40ft.
Hide People Involved
Number of people caught: 
0
Avalanche Location: