Touchy, small wind slabs

CB Avalanche Center2016-17 Observations

Location: Crested Butte Area
Date of Observation: 02/20/2017
Name: Zach Guy
Subject: Touchy, small wind slabs
Aspect: North, North East, East, South East, North West
Elevation: 9,000 – 12,500 ft

Avalanches: Skier triggered 5 or 6 shallow wind slabs, breaking on buried near surface facets, 6-18″ deep. All D1 in size. There were a couple of natural D1 wind slabs as well. These were all above treeline on leeward or crossloaded features. See photos.
Weather: Scattered skies. Light to moderate westerly winds, with short periods of light snow transport at ridgeline. Mild temps.
Snowpack: About 3″ of new snow, drifts from 6 – 18″ thick below ridgelines and in crossloaded features, mostly above treeline but a few near treeline slopes as well. The new snow is over .5 to 1mm reactive near surface facets, found at all elevations on northerly aspects, and on thick, meltfreeze crusts on southerly aspects. On east aspects N/ATL, the storm interface¬†was a thin, collapsible crust with facets below or just facets. There was not enough new snow for storm instabilities except where it was thickened from wind drifting. We primarily traveled on northerly aspects and found shallow wind drifts to be poorly bonded on the 2/17 near surface facet layer.

Collapsible crust on an E aspect NTL, with facets below.

Cracking in a 12″ wind drift over buried near surface facets, NTL.

Natural D1 wind slab. E aspect ATL

Skier triggered D1 wind slab, NW aspect ATL. Broke on buried facets.

D1 wind slab, SE aspect ATL.

Shooting cracks, ~30 feet long, on E aspect ATL; wind drift over facets.

Skier triggered D1 wind slab, N aspect ATL. Broke on buried facets.