Observation Date: 12/22/2019

Route/Location:
Southern Swan Range – Morrell mtn ridge

Weather:
12/21 and 22 both warm days with daytime temps above freezing and strong solar radiation on both days.
moderate SW winds and scattered clouds 12/21. light SW winds and few clouds 12/22.

Wind:

New Snow: No New Snow

Avalanche Activity:
small wet loose on steep solar aspects, mostly roller balls

Other Comments:
We dug many pits on most aspects during a 3 day Avy 1 course at treeline and below. W-N aspects were not observed.
No avalanches/cracks/collapses observed. Many roller balls/pinwheels on 12/21

Snow Depth: 85-120cm
There’s a 60cm+ slab atop a facet/crust/facet hoar combo that was our greatest concern and it showed a propensity for propagation in our tests (i.e. CTH/SC, ECTP, RB4/WB).

The slab seemed more stubborn in shaded/deeper areas (video here: https://youtu.be/E8yhKfmb2Fo) and was failing just below the ice crust on 2mm facets. At some locations we saw surface hoar (4mm+) mixed in just under the upper crust and we also found some depth hoar near the ground in some pits.

The surface developed a stout crust that formed on solar aspects over the weekend.
At some locations we observed a thin layer of surface hoar about 20-25cm down but it was not our layer of concern.

The persistent slab problem was our main concern at and below treeline and we managed our terrain by sticking to lower angle and densely treed slopes.

We saw small wind slabs but did not find them reactive.

Observer: George Dangelo