Avalanche

Hunter Hill

Evan Ross and Zach GuyGunnison
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Observation photo 1Observation photo 2Observation photo 3Observation photo 4Observation photo 5

Quick report

Cracking
specific
Collapsing
specific

Upper Cement Creek has a shallow and often wind-affected snowpack. The best skiing was above 10,800ft, but below the heavily wind-affected snow in the alpine.  That middle-elevation band was also where the snowpack showed the most obvious signs of instability. 

On Easterly to Northeasterly terrain features, shooting cracks and collapsing started to occur around 10,800ft and up to about 11,800, after which the snowpack became more heavily affected by recent winds, with a mix of eroded features and hard slabs that were quiet underfoot.

Weather

Cloud Cover
broken
Wind Loading
previous
Recent Snowfall
0
Snow Avail For Transport
none

A clear sky in the morning gave way to high, thin clouds in the afternoon. Calm to light winds.

Snowpack

Below 10,500ft the snowpack lacked much layering in this area. By the time we reached 10,800, there was some very soft slab development and a layered snowpack. An easterly facing slope at 11,000ft had a 70cm snowpack with about a 45cm soft slab above the December Dryspell Layer. Those soft slabs struggled to propagate far across the slope, in part because of the snowpack variability from past weather events. Another few hundred feet higher, the extra wind-loading and wind hardening of those slabs (still about 45 cm) made triggering an avalanche feel more likely with a couple of larger collapses, but the snowpack structure was still variable across slopes.

In the alpine, snow surfaces are often heavly wind effected. Many slopes are wind-eroded, while concave slopes and some lee terrain features have thick, hard slabs. We investigated one avalanche that failed on a south-facing slope at 12,200ft. Here, the northerly wind event had loaded the slope, with the avalanche failing in small facets between the 1/1 and  1/5 crusts.  The bedsurface of the avalanche was the thicker Christmas Crust. 

Avalanche

Size
D1.5
Type
HS
Count
9
Aspect
SW
Trigger
N
Elevation
12800 ft

Numerous hard slab avalanches ran during the past few days of northerly winds, averaging D1.5 in size. These were concentrated on the southern half of the compass above treeline. The one crown that we investigated was about 3 feet deep and failed on old, faceted crusts.