Persistent Slab structure harder to find but still there

CB Avalanche Center 2017-18 Observations

Location: Crested Butte Area, Washington Gulch
Date of Observation: 12/28/2017
Name: Evan Ross, Avalanche L1 Class

Subject: Persistent Slab structure harder to find but still there
Aspect: North East, East
Elevation: 9,700-10,900

Avalanches:

Searching for the right slopes produced shooting cracks and a collapsing snowpack but slope angles for two low for an avalanche to release.

Weather: Light northwesterly winds at ridgeline. Mostly clear sky.
Snowpack: Still a sensitive and spooky snowpack, but those locations are getting harder to find with each passing day. In this area, below 10,200ft the snowpack was effected by previous down valley winds. Windward features had a thinner snowpack that lacked PS structure. The cross-loaded terrain features that faced more ESE had better slab development but lacked much for weak layers below those slabs. Climbing above 10,200ft on an easterly facing aspect the snowpacks became deeper, partly because the slope was more protected from the wind. With PS structure becoming better developed and more widespread. We quickly transitioned into a snowpack that showed obvious signs to instability with collapsing and shooting cracks. We searched out a more shaded slope with more consistent snow coverage and were able to collapse the entire slope from the nearby trees with a small pocket slumping down hill.

At all elevations we traveled, the PS structure is breaking down as the upper slab has been faceting out.

Photos:

Traveling in the trees near this slope produced shooting cracks through the entire slope with this small slump down hill. The slope was concave and in the low 30 degree range.

Cross-loaded terrain features below 10,200 feet. Thin and faceted snowpack on the windward slopes. Wind-loaded slabs didn’t have much for weak layers below. given the thin previous snowpack.