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Location Name: 
Forecaster Observation - Lake McDonald area
Observation date: 
Tuesday, March 19, 2019 - 15:30
Is this an Avalanche Observation: 
Yes
Observation made by: Forecaster

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Quick Observation

Toured in the Lake McDonald area to assess the damage from the recent warmup.

  • Wet loose avalanche activity from the past few days was widespread on sunny aspects. Mostly D1 to D2 involving just last weekend’s storm snow. However, there were a few slides on the south face of Stanton and SW face of Vaught that had gauged to the ground, producing larger debris.  One of these slides off of Vaught produced a very startling amount of debris that ran almost full track (D3.5)
  • We spotted 4 large slab avalanches that recently failed on old snow layers on rocky, SW and W facing aspects at upper elevations, D2 to D3.
  • We started exiting avalanche terrain around noon to 1 pm. We did not see any avalanche activity prior to that, but saw some rollerballs on high, NE aspects. The snow surface became increasingly saturated and unsupportive but less reactive to ski cuts as we descended. We were able to produce rollerballs and pinwheels that gained volume at mid and upper elevations. At low elevations, the rollerballs disintegrated into mush without collecting volume. 
Snowpack, Avalanche, Weather Images: 
Snowpack Details
Snowpack and Weather Details: 
Hide Terrain
Elevation of observation: 
3500-5000 ft
5000-6500 ft
Above 6500 ft
Aspect(s) of observation: 
N
NE
E
SE
S
SW
Red Flags: 
Rapid or prolonged warming
Rollerballs / pinwheels
More comments about the snowpack and weather: 
At low elevations, 2-3” refreeze turned to knee deep wet grains by midday. Ski cuts on steep test slopes produced minor sluffs that dissipated quickly rather than collect volume; wet loose conditions seem to have moslty run their course at this elevation. At upper elevations on SE aspect, the water has only moved into the top 2-5” of the snowpack. Northeast aspects were getting moist for the first time today, probably the most reactive aspect for natural wet loose. North aspects still dry with small dry sluffing.
Wind Speed: 
Calm (No air motion)
Air temperature: 
Above Freezing
Sky Cover: 
Mostly Clear (FEW)
Avalanche Details
Avalanche Details: 
Date and Time of Avalanche: 
Sunday, March 17, 2019 - 15:30
Avalanche Type: 
Wet Loose
Failure Plane/Weak Layer: 
Old snow
More information or comments about the avalanche: 

3 different paths converged into one debris pile.  The terminus of debris looked like one event, not overlapping events.  Debris estimated 20 ft deep.  

Hide Trigger
Trigger: 
natural
Hide Terrain
Aspect: 
Southwest
Starting Elevation: 
above-treeline
Hide Size
Destructive Size: 
D3.5
Relative Size: 
R4 Large
Avalanche Length (Vertical Run): 
3000ft.
Avalanche Location: 
Date and Time of Avalanche: 
Sunday, March 17, 2019 - 13:30
Avalanche Type: 
Wet Loose
Failure Plane/Weak Layer: 
Old snow
More information or comments about the avalanche: 

Mt. Stanton. Observed start zones and tracks, couldn't see debris from my vantage. Ran full depth. Size estimated

Hide Terrain
Aspect: 
South
Starting Elevation: 
near-treeline
Hide Size
Destructive Size: 
D2.5
Relative Size: 
R3 Medium
Avalanche Location: 
Date and Time of Avalanche: 
Sunday, March 17, 2019 - 13:30
Avalanche Type: 
Wet Loose
Failure Plane/Weak Layer: 
New/old snow interface
More information or comments about the avalanche: 

Various elevations, mostly NTL/ATL on E, S, W aspects around Glacier Park

Hide Trigger
Trigger: 
natural
Hide Size
Destructive Size: 
D1.5
Relative Size: 
R2 Small
Avalanche Location: 
Date and Time of Avalanche: 
Monday, March 18, 2019 - 13:30
Avalanche Type: 
Hard Slab
Failure Plane/Weak Layer: 
Old snow
More information or comments about the avalanche: 

Dimensions estimated from a distance.  Failure date sometime in past 3 days. 

Hide Terrain
Aspect: 
Southwest
Starting Elevation: 
above-treeline
Hide Size
Destructive Size: 
D2.5
Relative Size: 
R2 Small
Crown Height: 
3 ft
Avalanche Location: