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Natural sluffs on Mt Brown
Location Name:
Forecaster Observation- Mt Brown, Glacier Park
Observation date:
Sunday, December 2, 2018 - 17:15
Is this an Avalanche Observation:
Yes
Observation made by:
Forecaster
Tabs
Quick Observation
We observed a dozen natural D1 loose dry avalanches that ran during the day or overnight, both on northerly and southerly aspects at mid and upper elevations.
On southerly aspects, the snowpack consisted of 4” of low density snow over soft recent snow over a supportive suncrust. There are Fist-hard facets below the crust and in some places above the crust.
No other signs of instability today. Calm winds, no precipitation, broken skies, no wind loading or slab formation.
Snowpack, Avalanche, Weather Images:
Snowpack, Avalanche, Weather Videos:
December 2, 2018: Natural loose avalanches on Mt. Brown
Video of December 2, 2018: Natural loose avalanches on Mt. Brown
Travel Details
Region:
Glacier National Park - McDonald Lake Area
Route Description:
Snyder Lake to Mt Brown up to 7800’’
Snowpack Details
Snowpack and Weather Details:
Terrain
Elevation of observation:
5000-6500 ft
Above 6500 ft
Aspect(s) of observation:
S
Persistent Weak Layers:
Facets or Faceted Crust
Buried
New Snow in the past 24 hours:
2.00in.
Total Snow Depth:
15-30”
More comments about the snowpack and weather:
Mix of ECTPH and ECTNH below the suncrust at 7700’. The crust is quite stout on due South. Would be most concerned about it collapsing on facets (after decent loading event) where it thins, such as SE aspects.
Blowing Snow:
None
Wind Speed:
Calm (No air motion)
Air temperature:
Below Freezing
Snow line:
Below valley
Sky Cover:
Mostly Cloudy (BRK)
Highest Precipitation Rate:
No Precipitation (NO)
Avalanche Details
Avalanche Details:
Date and Time of Avalanche:
Sunday, December 2, 2018 - 17:15
Avalanche Type:
Loose Dry/ Sluff
Failure Plane/Weak Layer:
New/old snow interface
More information or comments about the avalanche:
Mostly observed S aspects. Could hear N aspects on Edwards
Trigger
Trigger:
natural
Terrain
Aspect:
South
Starting Elevation:
above-treeline
Size
Destructive Size:
D1 Relatively harmless to people.
Relative Size:
R1 Very Small
Avalanche Length (Vertical Run):
400ft.
