Windslabs and variable persistent slab structure in Oh-Be-Joyful

CB Avalanche Center2014-15 Observations

Name: Zach Guy
Title: Windslabs and variable persistent slab structure in Oh-Be-Joyful
Location: Kebler Pass Area to Crested Butte Area
Date of Observation: 01/03/2015
Aspect: North, North East, South East, South, North West
Elevation: 12,000 feet to 9,000 feet

Avalanches: Widespread cracking on windloaded features and numerous touchy windslabs up to 10″ deep on SE aspects near and above treeline, running on the thin suncrust that formed yesterday. SS-ASc-R1-D1-I. See photos. Also some cracking and very thin pockets (2-3″ thick) released in relatively sheltered, northerly ATL terrain, potentially on the surface hoar layer that was observed yesterday(?) Didn’t look at the interface closely.

Weather: Overcast to broken skies. Strong NW winds, with moderate to heavy snow transport. .Moderate snowfall (S2), with about 2-4″ accumulated through the day.

Snowpack: Traversed from the headwaters of Oh-Be-Joyful basin to Slate River trailhead monitoring PS problem. Near the headwaters, at 10,000 feet in the far west end of the basin, the snowpack was 200 cm deep. In the pit, the Dec 13th facet layer was indiscernible to the naked eye and in hardness profiling, and it produced non-propagating results about 80 cm from the surface. (ECTN25, Q3 ). Moving east and gradually losing elevation, the layer became noticeable to pole probing (hollow feeling under denser slab) where the snowdepth was roughly 100 cm to 80 cm deep, just upvalley of where Peeler Basin enters Oh-Be-J at 9,600 feet. Around here we started noticing soft collapses underfoot. Further east down-valley, around 9,400 feet below the Redwell runout, the slab felt mostly gone to faceting, with easy pole probing throughout, no more collapses, and a snow depth around 40-60 cm.