Crown Profile from Skier Trigged avalanche, Left tele bowl

AVALANCHE OBSERVATION
Tele Bowl, Sherwins

Drainage:

Submission Info
Steve Mace
Forecaster
Saturday, January 19, 2019 - 4:00pm
Red Flags: 
Recent avalanche activity
Recent loading by new snow, wind, or rain
Avalanche Type: 
Slab
Slope: 
36degrees
Trigger type: 
Snowboarder
Crown Height: 
3 ft
Aspect: 
North
Weak Layer: 
Other - explain below
Avalanche Width: 
100ft.
Terrain: 
Below Treeline
Elevation: 
9 000ft.
Bed Surface: 
Old Snow
Avalanche Length: 
800ft.
Number of similar avalanches: 
2
More detailed information about the avalanche: 

I went up to investigate the recent skier-triggered avalanche in the left Tele Bowl, on the Punta Bardidi ridge in the Sherwins.  New snow made the investigation more difficult, but after comparing my observations to those made by the party on Jan 19, I am reasonably confident in my findings.   
The avalanche occurred on Jan 19 and was triggered by a snowboarder as he began his descent. The slab broke at his feet, and he was able to avoid being caught.  Crown height was estimated to be about 30” deep, and I found the width of the crown to be about 100’ and estimate that the debris ran about 800’ vertical.   (HS-AS-R3-D2-O)
My crown profile identified multiple factors that may have contributed to this avalanche. I was able to confirm the presence of preserved buried surface hoar mid-pack as well as the weak faceted grains about 45 cm from the ground. I found both weak layers to be reactive in compression tests.  In addition, I found evidence of wind loading in this location. I believe the bed surface of this slide was the weak faceted layer about 45cm from the ground; however, I think all three of these factors played a role in this avalanche.​

Avalanche Photos: 
Snowpit or crown profile photo or graph: 
Blowing Snow: 
No
Cloud Cover: 
25% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Moderate
Precipitation: 
None
Air temperature trend: 
Cooling
Wind Direction: 
North
Accumulation rate: 
None
Number of People Caught: 
0
Left Tele Bowl 37° 36' 46.7172" N, 118° 57' 42.5628" W
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