Who dropped the snow bomb?

Location Name: 
Forecaster Observation - southern Whitefish Range
Observation date: 
Sunday, January 12, 2020 - 19:15

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

Tabs

Quick Observation

Checked out lower elevations in the southern Whitefish Range, to see how the snowpack there has developed with colder weather and recent snowfall.

  • We saw the debris or crowns from a few small natural avalanches on southwesterly slopes. Recent snow and flat light obscured the crowns, though they looked to have run late Saturday and to have involved soft slabs of fresh snow. The debris looks to have run mid- to full-track. 
  • We found a surprisingly deep snowpack below 5000 feet. 1.5-2.5 m height of snow between 4 and 5000 feet. The snowpack is generally soft and unconsolidated, with few distinct weak layers. These weak layers include graupel and density changes, thin crusts, and a few small facets. None produced propagation in our tests.
  • Older weal layers, like the late-December crusts, are buried well over a meter deep; the grains look to be rounding. 
  • The snow surface is soft, low-density snow that will be readily hardened or drifted by strong winds. 
  • Slope cuts on steep road cuts did not produce any small slabs. 

Low elevation slopes in the Whitefish Range now have more than enough snowpack for avalanche hazards on open slopes, with sluffing and small soft slabs the concerns today. 

Snowpack, Avalanche, Weather Images: 
Travel Details
Region: 
Whitefish Range - Southern (south of Coal Creek)
Route Description: 

to 5900 feet

Snowpack Details
Snowpack and Weather Details: 
Hide Terrain
Elevation of observation: 
3500-5000 ft
5000-6500 ft
Aspect(s) of observation: 
NE
E
SE
S
SW
Red Flags: 
More than a foot of new snow or heavy snowfall rates (>1"/hr)
Persistent Weak Layers: 
Facets or Faceted Crust
Buried
Total Snow Depth: 
240 cm
More comments about the snowpack and weather: 
Snow showers of varying intensities through the day - S-1 to S5. Calm most of the day with some light gusts.
Blowing Snow: 
None
Wind Speed: 
Calm (No air motion)
Air temperature: 
Below Freezing
Sky Cover: 
Overcast (OVC)
Highest Precipitation Rate: 
Heavy Snowfall (S5)
Avalanche Details
Avalanche Details: 
Number of avalanches: 
2
Avalanche Type: 
Soft Slab
Failure Plane/Weak Layer: 
Unknown
More information or comments about the avalanche: 

Seen from Kimmerly Basin Rd, but could not see crown and determine SZ elevation. One other similar slide on same ridge, though D1.

Hide Trigger
Trigger: 
natural
Hide Terrain
Aspect: 
Southwest
Starting Elevation: 
below-treeline
Hide Size
Destructive Size: 
D1.5
Avalanche Location: