Multiple old, now snow-covered SS-N-R2-D2 or 3 on various aspects of E, N, NW in NTL band or on steep rollovers BTL. The storm cycle winding down 4/5/6 January 2021 overwhelmed the weak snowpack across the Wenatchee Mountains.
Signs of Unstable Snow
Did you see shooting cracks?
Did you experience collapsing or whumpfing?
Calm and Clear turning Obscured with light east winds as valley fog rose to 6000'+ by noon. Surface hoar BTL and NTL. Wind not enough to transport snow NTL at 1200. 12/9, 12/22 crusts with weak snow and 1/3-1/4 density changes easily identified in pit at 5800' N. No tests conducted.
Observed Avalanche Problem #1:
25cm from snow surface, the density change in the storm is reactive under foot and easily identified in pits. Where wind has packed snow into a cohesive slab this layer is the source of collapses while traveling NTL.
Observed Avalanche Problem #2:
HS 120-150cm, with bottom 15-25cm fist hard depth hoar/facets. Local collapses BTL in areas with 90cm of snow or more, five days after the storm passed.