Avalanche

West Seeley

Arden FeldmanSeeley Lake
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Quick report

There was around 12" of new snow at mid to upper elevations in West Seeley, which made for good riding conditions. 

We found widespread poor snowpack structure on shaded slopes with a 1.5 foot thick slab resting on surface hoar and facets. In wind protected areas, the slab seems like it is on the verge of being strong enough to propagate a failure. We didn't observe any direct signs of instability on the layer, other than propagation in one of our snowpits. Some riders pushed into steeper terrain without triggering avalanches. We didn't make it into more wind loaded terrain, but I would be concerned about more sensitive conditions where the slab is more consolidated. 

With sunny skies, the fresh low density snow was quickly heating up and producing rollerballs and small wet loose avalanches on steep south facing slopes. 

Weather

Air Temp
Warm
Cloud Cover
few
Wind Loading
previous
Recent Snowfall
30
Snow Avail For Transport
moderate amounts

It was a beautiful sunny day with calm to light winds and warm temperatures.

Snowpack

We dug three quick snow pits on north facing mid elevation slopes. On shaded mid to upper elevation slopes, there is widespread poor snowpack structure with a 1.5 foot thick slab resting on a layer of surface hoar and/or facets. The top 12" of the slab was new snow, which was resting on a thin rain crust, and then there was 6" of older snow. The slab was not very strong or consolidated in wind protected areas. In two of the pits, the surface hoar was well preserved and 1-2 cm in size. In the other pit, which was on a more wind affected slope, there were only facets at the interface. Extended column tests propagated in one of the pits, but did not propagate in the other two. I would be especially concerned about persistent slab avalanches in wind loaded areas, where the slab is thicker and more consolidated. 

 

Avalanche

Size
D1.5
Count
3
Aspect
NE
Trigger
N
Elevation
7000 ft

We observed several small natural wet loose avalanches on steep sunny slopes. They were confined to the fresh snow, which quickly heated up on sunny slopes. One loose wet avalanche on Crescent Mountain in the Swan Range ran a long distance but still appeared relatively small. We also observed a small slab avalanche that failed just below a cornice in a heavily wind loaded northeast aspect. It was likely a wind slab that failed mid-storm.