Avalanche

West Side Swan

FACSwan Range
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Observation photo 1Observation photo 2Observation photo 3Observation photo 4

Quick report

Cracking
isolated

Today we went to the favored Swan Range to get a taste of some deep snow and see what problems were developing. 

Two takeaways:

1. Don't trust wind-drifted snow. We unintentionally triggered a slab that failed 1 to 1.5 feet thick that took me off my feet. I only went a short distance due to the relatively benign terrain we were in. The slide was triggered just below a ridgeline with light wind drifting. 

2. Excellent riding in wind-protected terrain. We managed sluff by selecting slopes with slope angles less than 38 degrees. Sluffs only ran short distances in this terrain. More aggressive tactics would be needed in steeper terrain because sluff did entrain snow as it moved downslope. 

 - NOTE: This slab failed on a persistent weak layer (Surface Hoar) that likely formed Wednesday or Thursday. This layer was beneath a harder windboard under the new snow. See video for more information. 

 

 

Evidence of drifting snow. A loose-dry problem that felt on the verge of being a storm slab problem in wind-protected locations. Few loose drys did begin to fracture into small soft slabs.

Weather

Air Temp
Below Freezing
Cloud Cover
obscured
Wind Loading
moderate
Recent Snowfall
6 inches and 12 inches in 24hr.
Snow Avail For Transport
moderate amounts

Steady moderate to heavy snowfall. Precip rates appeared to be higher below 6000 feet. There were roughly 3 inches on the sled during the 4-hour tour.

Snowpack

Snowpit at 6650 on NW Aspect. HS280. ECTNM down 30 cm (1 foot) on new/old snow interface. We dug roughly 1.5 meters and never found older buried weak layers. 

Avalanche

Size
D1 R1
Type
L
Count
2
Aspect
NW
Trigger
AS
Elevation
6000 ft

Muliple loose dry triggered intentionally on descent. Easy to manage. Few cracked and behaved like soft slab.