Mitre Couloir and Col
Banff Yoho & Kootenay National Park
Meshwell Boschmann , Thursday 21st November, 2019 8:30PM
Great day out in a quiet place. Noticed about 20 tracks down Surprise Pass on the ski out.
Snow conditions were: Deep powder, Powder. Weather conditions were: Cold. We rode: Alpine slopes, Steep slopes. We avoided: Sunny slopes. Riding quality was amazing.
Elevation: 2450m. Aspect: NW. HS 147cm. Angle: 33 degrees. Results: CTE 6 sudden planar down 20 on graupel CTH 25 sudden collapse down 145 in facets over glacier ice CTH 30 resistant non planar down 50 in facets over November 8 crust 130 to 170 cm on the glacier except for the more exposed toe which had 70cm. Topped out in the couloir and it skied amazing. Ran into thinly burried 5cm thick 1F windslab 50m below the Col proper. Turned around at this point given the abundance of graupel crystals found underneath.
Light catabatic wind as we were approaching the glacier and the run in the morning. No wind whatsoever while we were ascending and descending the very sheltered run. Wind picked up at ridge top (3400m+ on Lefroy and Victoria) in mid afternoon and some good steady snow plumes could be observed.
Observed on a slope 500m north of the Mitre Col main rain. Seem to have run on the November 8 crust. Facets suspected above crust (as observed in our test pit). Couldn't identify the trigger on our way in but did notice one very large rock in the debris. Seems like the rock detached from a wall above and triggered the slab. See picture.
Source: Avalanche Canada MIN