Quick report
We traveled to an upper elevation ridge in the Skyland/ Challenge Cabin area to investigate the Wind Slab avalanche problem.
- Plenty of evidence indicating winds have been active in the area, including snow blown off trees on the windward side of ridges and exposed features, scoured patches on the windward side of an upper elevation ridge, and flagging/ plumes of blowing snow mid-late morning in John F. Stevens Canyon.
- However, we found few no fresh wind slabs - soft or hard - on the lee side of a ridge, none of the textured surfaces we would expect with strong winds, and only small cornices.
- The fresh/ recent snow is loose, in part because most of the grains are graupel or rimed precipitation particles. It sometimes held together as a very soft block/slab in active tests or column tests.
- The snow immediately below is firmer at 4 finger to 4 Finger + hardness. This may be old wind board/ drifted snow from last week's powerful winds. In large, open bowls prone to toploading or crossloading, this firmer snow may form thick, stubborn hard slabs.
- We did not find any persistent weak layers in a profile at ~7000 feet on a northerly slope. We heard no collapses and the only cracking we observed were some short, radial cracks below 6000 feet; they resulted from a melt-freeze crust breaking under our weight.
And Yes, Virginia, there is good riding out there, the kind that seemed unlikely with the weather of the past week.
Weather
- Cloud Cover
- broken
- Wind Loading
- light
- Rain Elevation
- 4000'
- Recent Snowfall
- 7-20 cm
- Snow Avail For Transport
- moderate amounts
Light but gusty SW winds near ridge crest, though quiet below. S-1 snow showers, mostly graupel and rimed particles. Cool temps - upper teens/ low 20s at ridge. Broken skies that made for some nice light at times
Snowpack
New/ recent snow over hard, refrozen snow.
In a profile at about 7000 feet on a northerly slope, we found no apparent persistent weak layers above the refrozen base. We did find a weak layer of graupel about 30 cm below the snow surface (HS 165; F to 4F+ slab; ECTN14) that didn't produce propagation in a large column test.
However, in hasty pits/ hand pits between ~5000 and ~6000 feet, we found 2 melt-freeze crusts or ice layers above the hard, refrozen base. These are stacked right on top of each other near 5000 feet, and the bottom one is surprisingly slick. The upper one slid off easily in hand pits even though no weak layer was apparent. The crust and ice layers get further apart with elevation; in between are refrozen percolation tubes and soft grains that didn't feel like facets, though I didn't look through a loupe.