Lost Johnny

Yup. The rumors are true. It is deep. Like real deep. Today we went to the northern Swan Range to check snow depth, wind transport, and suss out any buried persistent weak layers. 

• We observed one large (D2) natural avalanche. This avalanche failed on an east-facing slope at roughly 7000 feet along the Swan crest. The crown was in wind-loaded terrain and just downslope of a large cornice. 
• We experienced one audible collapse on a SE aspect at roughly 6200 feet. At this same elevation, we noticed more wind-affected snow. 
• We found a weak layer of near-surface facets resting on a thin crust. I suspect this was the layer that collapsed.
• In a different location with the same aspect, we triggered a 2 foot thick soft slab. This slab failed on the same facet/crust combination. The avalanche occurred on a short, yet steep slope. This slab failed while the second person was crossing it. No one was caught. 
• Fresh cornices were easy to trigger but did not trigger any slabs below. I would assume the story would be different in areas experiencing stronger winds. 

 

Audible collapse on a SE aspect at roughly 6200 feet. The triggered avalanche occurred on a SE aspect at roughly 6300 feet. More information is in the avalanche tab.

Storm totals ranged from 55 to 65 cm. 

SE aspect: Crust/facet combo beneath storm snow. This was the weak layer that failed in the avalanche we triggered. 

E aspect: A layer of 2mm facets exists beneath the storm snow. ECTN22 on this layer. New snow in wind protected terrain is Fist-.