Valanga

West Brush Creek

Zach GuyGunnison
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Quick report

Cracking
specific
Collapsing
specific

It was easy to remotely trigger large avalanches on wind-loaded slopes near treeline, and we also experienced obvious signs of instability in sheltered terrain on shadier aspects.  We avoided steep slopes on north to east aspects, and found good stability on a steep, southeast facing slope below treeline, which was just a stack of suncrusts with 6" to 8" of new snow on top.  

Collapsing increased in frequency and loudness as we gained elevation. Collapsing and cracking began around 10,000' with soft collapses that radiated 20 to 50 feet, and evolved to large, booming collapses in wind loaded terrain above 11,500'.

Weather

Cloud Cover
few
Wind Loading
previous
Recent Snowfall
15 to 20
Snow Avail For Transport
moderate amounts

Snowpack

In wind sheltered terrain above 10,000', slabs were 45 to 50 cm thick (F to 4F) over well-developed facets and depth hoar layers (F hard).  The Christmas rain crust separating these layers is thinner than what I've seen in areas like Schuylkill Ridge - about 2 -3 cm on shady aspects at 10,000' and thins out by 10,700'.  Collapses appeared to be failing just below the crust.  On windloaded slopes NTL, slabs were 100 to 120cm thick (up to 1F), and failed on the 11/30 depth hoar layer on the ground.  At those locations, the Christmas facet layer was 4F and rounding.  

Avalanche

Size
D2
Type
HS
Count
4
Aspect
NE
Trigger
AS
Elevation
11600 ft

We remotely triggered two large persistent slabs on windloaded slopes near treeline, facing N and NE. We did not see any natural activity in this basin.