Post-storm observations from the Northern Whitefish Range

Location Name: 
Forecaster Observation - Grave Creek, Whitefish Range
Observation date: 
Monday, February 26, 2018 - 20:30
Is this an Avalanche Observation: 
Yes
Observation made by: Forecaster

Tabs

Quick Observation

We toured into an area that saw favored snowfall in the past 24 hours to check the sensitivity of storm slab and wind slab problems.  We found both problems are becoming more difficult to trigger compared to yesterday.

  • ~10" of settled storm snow over a lower density layer produced moderate shears in hand pits, but was unreactive to snowmobile or ski cuts on numerous test slopes.
  • We produced localized cracking in wind drifted areas.  A pit on a windloaded slope produced hard, propagating results in a 2 foot thick wind slab.
  • We saw two fresh wind slabs, D1 in size, below leeward ridgelines above 6,000'.  
  • Today's weather:  Light winds and a mix of sun and snow. 
Snowpack, Avalanche, Weather Images: 
Snowpack, Avalanche, Weather Videos: 

February 26, 2018. Managing storm instabilities in the Northern Whitefish Range

Travel Details
Region: 
Whitefish Range - Northern (north of Coal Creek)
Route Description: 

Grave Creek to Weasel Lake and Bald Mountain, up to 6,400'

Snowpack Details
Snowpack and Weather Details: 
Hide Terrain
Elevation of observation: 
3500-5000 ft
5000-6500 ft
Above 6500 ft
Red Flags: 
More than a foot of new snow or heavy snowfall rates (>1"/hr)
Rollerballs / pinwheels
New Snow in the past 24 hours: 
12.00in.
More comments about the snowpack and weather: 
Some rollerballs on low elevation southerlies with afternoon sun. In a wind drifted NE slope, ECTP21, SP on stellar dendrites below a 4F slab.
Avalanche Details
Avalanche Details: 
Date and Time of Avalanche: 
Sunday, February 25, 2018 - 20:30
Avalanche Type: 
Soft Slab
Failure Plane/Weak Layer: 
Within storm snow
More information or comments about the avalanche: 

Wind slabs below cross-loaded ridgline on Bald Mtn

Hide Trigger
Trigger: 
natural
Hide Terrain
Aspect: 
Northwest
Starting Elevation: 
above-treeline
Hide Size
Destructive Size: 
D1 Relatively harmless to people.
Relative Size: 
R1 Very Small
Crown Height: 
1 ft
Avalanche Location: