Avalanche

Microdot

Peterson, RogersHatcher Pass
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Observation photo 1Observation photo 2Observation photo 3Observation photo 4Observation photo 5Observation photo 6

Quick report

Cracking
specific
Collapsing
isolated

We traveled to Mircodot today to look at a recently triggered avalanche (01/31) on the sunny side. This avalanche was likely triggered by skiers near or on the slope, and fortunately, no one was caught or carried. The slide was triggered after several parties had already skied the slope. The avalanche failed on buried weak layers near the ground. The takeaway was that shallow spots remain a concern for triggering avalanches. The additional weight from last week's snowfall was enough to push these weak layers to their brink. The slope could be described as shallow and wind-affected with visual clues such as exposed rocks in the start zone, and signs of previous wind loading near the ridge. 

Weather

Cloud Cover
few
Wind Loading
none

Mostly sunny skies and light north wind.

Snowpack

Surfaces and Upper Pack: On our approach, we found a faceting surface on westerly, northly, and southerly aspects that we traveled on. Where last week's winds had built drifts near the ridge, they were already beginning to facet away. 

Avalanche Crown and Flank: This slide failed on weak snow near the ground. The crown ranged from 1 to 3 feet thick, and was roughly 50-75' wide. Near the bottom of the path, the slide took out another pocket of deep snow—likely contributing to the large fanned-out debris pile. We performed stability tests in the crown and the flank of the slide. At the crown, the HS was 75cm, and stability tests yielded ECTP 15 and 21 results. We found a marginally deeper snowpack near the flank of the slide and found similar results in stability tests, ECTP 21 and 25. The first stability test yielded ECTPV results, although this result may not have been representative due to rocks near the base. 

01/26 Crusts: We did not have unstable results on the 01/26 crust complex, where the Mid-January melt freeze crust and the 01/26 rain/fog crust sandwiched small grain facets. Although in handpits this layer was able to peel away. 

Avalanche

Size
D2 R2
Aspect
S
Trigger
AS
Elevation
4500 ft

This avalanche was likely triggered from a shallow spot either near the ridge or from the edge of the slope. We found shooting cracks near the crown. This avalanche failed on weak snow near the ground, where the snowpack depth was variable. While approaching the crown, we found barely covered rocks in some spots, and deeper pockets of snow scattered across the slope.