Avalanche

White Cloud Foothills

PetersonGalena Summit & Eastern Mtns
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Observation photo 1

Quick report

Cracking
widespread
Collapsing
widespread

Signs of instability were widespread, including cracking, collapsing and a small skier triggered avalanche in wind loaded terrain. These signs of instability were more prominent where old snow exists below recent storm snow, and in wind affected areas. 

On solar slopes where recent snow fell onto bare ground, cracking and collapsing was confined to the new snow over the sagebrush. Where old snow exists below recent snowfall, collapses and cracking were larger and more pronounced. On a north-facing slope at 7300' I remotely triggered a small avalanche. This slope was wind loaded and broke 1-3' thick and 150' wide.

Weather

Cloud Cover
overcast
Wind Loading
moderate
Rain Elevation
6500
Recent Snowfall
35cm since 12/25
Snow Avail For Transport
moderate amounts

Overcast skies and consistent S1-S2 snow showers. Precipitation was a mixture of snow and rain near, 6500' (Mostly rain in Stanley). Moderate-strong S winds, decreased by 1:00PM.

Snowpack

New snow and HS: Snow totals since 12/25 is ~35 cm. Below 7000' snowfall over the last 24 hours is more dense and moist than the snow from the start of the storm. HS ranged from 35cm at low elevations to ~75cm in wind sheltered areas above 7000'. 

Weak layers: On shaded slopes below 7000', new snow sits above 10-15cm of faceted snow. (NW, 6900', ECTP7). Above 7000', the 12/7 & 12/13 weak layer produced unstable results in stability tests (E, 7300', HS 78, ECTP11 @25). 

I remotely triggered a small avalanche on a north-facing wind loaded slope at 7300'. This avalanche failed on facets near the ground above a stiff crust, likely on mid-December weak layers. 

Avalanche

Size
D1 R2
Type
HS
Aspect
N
Trigger
AS
Elevation
7300 ft

A skier remotely triggered this avalanche from a ridgeline above. The slope was wind loaded, and the avalanche was triggered while stepping onto a small cornice. This avalanche failed on the mid-December weak layers.