Pittsburgh slab

CB Avalanche Center2016-17 Observations

Location: Paradise Divide Area
Date of Observation: 02/27/2017
Name: Evan Ross
Aspect: North East
Elevation: 9,200-10,400

Avalanches: Investigated the crown profile of a human triggered avalanche on 2/26. Test results below. Bed surface averaged 37 degrees and crown averaged 14 inches thick breaking into old snow layers. Debris looked to be D1.5 in size. Could have been larger if the terrain was bigger.

After an additional 4″ of new snow, a ski cut on the skiers left flank propagated another soft slab an additional 240ft wide across the rest of the 37 to 40 degree slope.
Weather: Overcast sky in CB became obscured by S-1 snowfall heading out to Pittsburgh at 10am. snowfall picked up to S2 just after noon and continued as we headed home about 2pm. Light and variable winds below treeline with some stronger gusts.
Snowpack: 10 to 14″ of snow has accumulated during the last week over two different NSF interfaces. 2″ were added last night with another 2″ added by 2pm. These NSF layers are each capped by slightly firmer NSF grains (half step hand hardness). Probably from a temporary period of warming before getting buried. The NSF grains are .5 to 1mm in size and 3 to 6cm’s thick, with weak fist hardness.

Basically no obvious signs to instability while up tracking on slopes up to 37 degrees in steepness, with the current slab being so soft. Hand pits produced sheers at the upper NSF interface. Crown profile had an ECTP 15 SC on the upper NSF and an ECTPN on the lower NSF interface which was the weak layer in this human triggered avalanche.