Winds and new snow in the Middle Fork

Location Name: 
Cascadilla Creek
Observation date: 
Tuesday, January 11, 2022 - 16:15

Is this an Avalanche Observation: 
No
Observation made by: Professional Observer

Tabs

Quick Observation

We toured in the Middle Fork corridor this morning to check on wind slab development and new snow accumulations.

  • Just below the ridgeline at 5700 feet, we found developing, reactive wind slabs on leeward aspects.
  • Snow accumulation and wind speeds increased during the course of the day.  We noted 2 inches of new snow at lower elevations by 2pm. 
  • We found a 1 inch thick rain crust to 4500 feet.  Above that we found stout wind slabs on exposed aspects.
Snowpack, Avalanche, Weather Videos: 

Small Intentionally Triggered Wind Slab

Travel Details
Region: 
Flathead Range - Middle Fork Corridor
Activity: 
Skiing
Snowpack Details
Snowpack and Weather Details: 
Hide Terrain
Elevation of observation: 
3500-5000 ft
5000-6500 ft
Aspect(s) of observation: 
N
NE
E
Red Flags: 
Blowing snow
New Snow in the past 24 hours: 
3.00in.
More comments about the snowpack and weather: 
We toured in Cascadilla Creek today to look for developing wind slabs. Light snowfall at the start of the tour increased during the course of the day, at one point reaching 2 centimeters per hour. By noon the wind was increasing, with blowing snow at mid and upper elevations. Winds in the canyon were predominantly from the E-NE, while strong ridge gusts from the S were noted. We noted a 1 inch thick, pencil hard rain crust up to 4500 ft. Below this crust is a mix of fist hard graupel and soft snow. The rain crust gave way to a mix of soft snow and stiff wind board. In exposed N and NE locations, this wind board was up to 6 inches thick. Undercutting this layer resulted in cracking and easy failure. 45centimeters of fist hard graupel rests beneath the wind board. Winds at the ridge top (5700 ft) were strong and forming wind slabs on N and NE aspects. Stomping on small tests slopes caused fractures 4-8 inch deep (see video). Failure occurred on 1 finger hard old wind slab. We dug a small test pit in a wind drifted area just below the ridge line at 5700 feet. We had non-propagating results (ECTN7) 25 centimeters below the surface. We confirmed our ECT result with a CT test (CT11), sudden planar failure. Failure occurred on a fist hard graupel layer sandwiched between two 4 finger hard wind slab layers. We returned to the car at 2 pm to find 1 inch of new snow accumulation.
Blowing Snow: 
Moderate
Wind Speed: 
Moderate (Small trees sway)
Wind Direction: 
South
Air temperature: 
Below Freezing
Snow line: 
3000 ft
Sky Cover: 
Overcast (OVC)
Highest Precipitation Rate: 
Moderate Snowfall (S2)