Observation: Public
Observation Details
Name:
Enji CooperObservation Date:
December 14, 2021Submitted:
December 14, 2021Zone or Region:
Snoqualmie PassActivity:
XC Skiing/SnowshoeingLocation:
Moolock MountainTriggered Avalanches
Did you trigger any avalanches?
YesWas it intentional?
NoAvalanche Type:
Soft SlabSize:
Size 1: Relatively harmless to peopleElevation:
Above treeline (4.2k'+)Aspect:
SComments:
Almost triggered a D1.5/D2 avalanche with snowshoes above partner when coming down steep (35°+) slope when I tried to reduce ascent angle by creating switchback. This caused a 2' by 2' triangular slab to slide down the fall line. Fortunately terrain breaks prevented it from continuing downhill, entraining more snow going from D1.5 to a D2 avalanche. The snow of concern matched storm/[soft] wind slab characteristics and was over a weak interface which was buried approximately 3"~5" deep. The slab broke cleanly (non-diffuse).Signs of Unstable Snow
Did you see shooting cracks?
Yes, IsolatedDid you experience collapsing or whumpfing?
Yes, IsolatedObservations
Observed items of concern today above treeline near Moolock Mountain.
Ascended mountain bike trail between Moolock Mountain and Bootalicious Peak. Observed coherent slab over stout rain crust below treeline (snowshoe penetration was approximately 3"). Rain crust instability was not a concern due to low temperatures (low 30s, high 20s) and lack of precipitation input (rain) or sunshine.
Near/above treeline, however, the conditions changed: the snowpack deepened considerably (found powder stashes in excess of 3' in talus fields). We tried to stick to forestry road, the ridge, then drop in to Moolock from the saddle, but due to unforeseen obstacles along the ridge (blowdowns, boulders, etc), we were forced down along the S ridge of the high point between Bootalicious and Moolock (false summit): 47.54337, -121.64495 WGS84 (point is unnamed on USGS quads). This is where we found areas of concern: wind fetch stashes in excess of 3', 3" storm slabs over ill bonded snow (presumed graupel due to temperatures over the past 24 hours), which broke in a _non-diffuse_ manner, and was very prone to sliding with snowshoes. We tried to mitigate risk by avoiding slopes in excess of 35°, but it was extremely difficult, given the low coverage in some areas, resulting in hidden talus/boulders and their respective gaps.
Much of the S aspects of the ridge and the ridgeline itself, where wind was allowed to blow, were wind scoured, however many leeward/protected areas were where wind fetch was collecting.
Weather was broken in the morning without precipitation, but by late morning (10:00~11:00), the weather had transitioned from calm to breezy (10mph+ sustained along the ridgeline), with varying cardinal directions coming mostly from the W and N.
Cornices were forming over W/S aspects in some areas (along the road) and N/NW/W in others (Moolock), which was odd since it wasn't consistent.
Lots of sluffing was observed when we disturbed snowpack on slopes over 30°. Where I could better control the snow along the road, I disturbed the top-layer with my trekking pole and pushed it downhill to avoid sliding.
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