Arrowhead, NE bowl. Possibly D2.5. Ran at least 500ft vertical w debris stopping ~4.7k. Suspect this was a slab, running on Dec 12th PWL. Poor viz and couldn't confirm crown.
Signs of Unstable Snow
Did you see shooting cracks?
Did you experience collapsing or whumpfing?
It appears there was a cycle of persistent slab avalanches overnight on Dec 18th on polar aspect. Mostly D2, some D2.5.
We stayed mostly below treeline. Found reactive fresh drifts on the ridge at 5.6k. Surface crust to 4.8k in the trees, maybe only to 4-4.2k in open terrain.
Profile at 5k, NNE:
Height of Snow (HS) 125cm
↓47cm Dec 12th facets (1.0mm), well-rounded
Test results did not indicate propagation at this location
Observed Avalanche Problem #1:
Near and below TL. Possible. Up to large. Would have taken unsupported terrain, and slopes >40deg to
Observed Avalanche Problem #2:
Did not directly observe. Suspect near and above TL, mostly on polar aspects. Very likely, Large to Very Large (D2-3).