Forecaster Observation - Marion Lake, Flathead Range

Location Name: 
Forecaster Observation - Marion Lake, Flathead Range
Region: 
Flathead Range - Bob Marshall Wilderness
Date and time of observation: 
Sun, 03/12/2017 - 12:00
Location Map: 

Red Flags: 
Recent loading by new snow, wind, or rain
Observation made by: Forecaster
Snowpit Observations
More detailed information about the snowpack: 

The objectives for today's tour was to determine the overnight elevation of the rain/snowline, wet loose avalanche potential of the snow surface at all elevations, evidence of both current wind loading and near surface instabilities.

  • Rain occurred overnight and through the morning in the Essex area with the snowline at approximately 5400'.
  • The snow surface was saturated below 5400' and was capable of producing wet loose slides below this elevation. Elevations above 5400' did not have a snow surface capable of producing wet loose slides of any significance today. 
  • Wind loading was observed at both mid and upper elevations. The wind loading at mid elevations was a surprise to us considering the dense nature of the new snow that was being blown around. An example of this loading was that our skin trail well below Marion Lake (~5900') was blown in our descent approximately 2 hours after we put this trail in. 
  • Winds were moderate with occasional strong gusts at ridgeline elevations which resulted in consistent snow transport. 
  • Wind slab conditions were observed at both mid and upper elevations. This slab sat atop lower density snow that was recently deposited. Cracking in the surface slab was frequent throughout our tour but propagation was minimal.
  • Our snowpit on a wind loaded north aspect at 6800' was 420 cm deep. Several near surface easy failures associated with density changes were observed in the top 50 cm during our ECT/CT tests with partial propagation. The February 9 and 17 rain crust was Pencil hard, 20 cm thick and 160 cm below the snow surface. Shovel shear tests resulted in failures on this layer with easy force. The failure layer was a thin layer of decomposing facets that sat on top of the crust. No results were observed in our CT and ECT tests on this layer. 
  • Our snowpit on a south aspect at 6700' was 300 cm deep. Several near surface easy failures associated with density changes were observed in the top 50 cm during our ECT/CT tests with partial propagation.The February 9 and 17 rain crust was Pencil hard, 20 cm thick and 120 cm below the snow surface. Shovel shear tests resulted in failures on this layer with easy force. The failure layer was a thin layer of decomposing facets that sat on top of the crust. No results were observed in our CT and ECT tests on this layer. 
Snowpit or crown profile photo or graph: 
Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
75% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Moderate (Small trees sway)
Precipitation: 
Snow
Air temperature trend: 
Warming
Wind Direction: 
Southwest
Accumulation rate: 
Less than 1 in. per hour
More detailed information about the weather: 

During our tour rain turned to snow at approximately 5400'.

Activity: 
Skiing
Precip Rate: 
S -1; very light snowfall, trace to 0.5cm/hour