Avalanche in Sherwins - Old Growth below The Perch

AVALANCHE OBSERVATION
The Sherwins

Drainage:

Submission Info
John Wentworth
Thursday, January 17, 2019 - 10:00pm
Red Flags: 
Recent avalanche activity
Avalanche Type: 
Slab
Slope: 
30degrees
Trigger type: 
Natural
Crown Height: 
3 ft
Aspect: 
North
Weak Layer: 
Storm Snow
Avalanche Width: 
300ft.
Terrain: 
Below Treeline
Elevation: 
9 000ft.
Bed Surface: 
Ground
Avalanche Length: 
150ft.
More detailed information about the avalanche: 

While descending at dusk in the old growth trees in the Sherwins below The Perch, I came across this severe crown about 2/3 of the way down.  Note that the crown occurs at a roll-over and a "steepening" of the terrain, and is very difficult to see while descending.  Further investigation revealed that the crown appears to have propogated for several hundred feet in either direction across the face, and appears to have been a catastrophic event.  The avalanche itself went "to the ground."  The bed surface had some snow on it - perhaps indicating that the avalanche happened towards the end of the storm on Thursday night January 17 - and the bed surface is marked with penetrating rocks and trees.  As it was apporaching dark, there was not sufficient time to conduct a detailed analysis.  This is a very dangerous situation for skiers descending through what is normally a reliably stable and relatively "safe" section of the Sherwins - I have skied in this sector for 15+ years and have never seen this type of event in this sector.  NOTE:  Skiing into the remnants of this event would be very dangerous with significant potential consequences.  I would encourage one of the ESAC avalanche forecasters to visit the site and conduct the appropriate technical analysis and provide the appropriate warnings.  I'm more than happy to provide any further information as desired.

 

 

Avalanche Photos: 
Air temperature: 
Above Freezing
Air temperature trend: 
Static
More detailed information about the weather: 

The air was warm and humid - warming temperatures in the afternoon were noticeable but the event appears to have happened during the recent storms.

The Sherwins 37° 36' 36.4896" N, 118° 58' 32.7756" W
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