Deep slab observations, rollerballs, and minor cracking in the Swan

Location Name: 
Forecaster Observation - Peter's Ridge, Swan Range
Observation date: 
Tuesday, January 9, 2018 - 14:00
Is this an Avalanche Observation: 
No
Observation made by: Forecaster

Tabs

Quick Observation
  • Above 5500', 2"-3" of dense new snow over a variety of melt-freeze crusts and rain crusts appeared to be bonding fairly well.  Some minor cracking near ridgelines, where drifts were up to 6" thick.  
  • The snow/rain line was at 5300'.  Moderate snowfall above that, moderate rain below that.  Moderate Southwest winds at exposed ridgelines with light snow transport. Snowfall was increasing in intensity (S2 to S5) as we were leaving at 2pm
  • We observed rollerballs up to 5500', but no wet loose avalanches.  The snow surface appeared to be pretty worked over by rain at the lowest elevations. The most active rollerball activity was around 5,000'  
  • The Thanksgiving crust/facet layer produced propagating results below a 120-140 cm hard slab.  We saw no signs of instability on this layer and no recent avalanches.  Probing at several locations suggests this structure is fairly uniform and the snowdepth is consistent across the mid/upper elevation terrain that we traveled.
Snowpack, Avalanche, Weather Images: 
Snowpack, Avalanche, Weather Videos: 

January 9, 2018. Deep slabs in the Swan Range

Travel Details
Region: 
Swan Range - West Side (Flathead Valley access)
Route Description: 

Peters Ridge up to 6,600 ft. 

Activity: 
Skiing
Snowmobiling
Snowpack Details
Snowpack and Weather Details: 
Hide Terrain
Elevation of observation: 
5000-6500 ft
Above 6500 ft
Aspect(s) of observation: 
S
SW
W
NW
Red Flags: 
Rain on snow
Rollerballs / pinwheels
Persistent Weak Layers: 
Buried
New Snow in the past 24 hours: 
3.00in.
Total Snow Depth: 
195 cm
More comments about the snowpack and weather: 
See pit.