Avalanche: Tony Grove

Observer Name
Eric and Amy Flygare
Observation Date
Monday, March 25, 2019
Avalanche Date
Monday, March 25, 2019
Region
Tony Grove
Location Name or Route
Tony Grove
Elevation
9,000'
Aspect
North
Slope Angle
40°
Trigger
Snowboarder
Trigger: additional info
Unintentionally Triggered
Avalanche Type
Hard Slab
Avalanche Problem
Persistent Weak Layer
Weak Layer
New Snow/Old Snow Interface
Depth
2.5'
Width
40'
Vertical
500'
Comments
We rode in the Tony Grove Area today.  We found excellent powder riding in the morning but it began to get sloppy by later afternoon.   I would imagine most slopes will have some crusts tomorrow.
 
We had several slab avalanches break on us throughout the day on north facing slopes above 8500 feet.  The most significant of the slabs was about 2.5 feet deep and 30-40 feet wide and failed on a north facing 40 degree slope.  The slide ran for about 100 feet then nearly stopped on a flatter bench but then continued over another steep section and stopped about 500 vertical feet below.  As soon as I noticed the slab window paning around me, I was able to outrun the avalanche since it was not particularly fast running and nearly stopped at the bench within 100 feet of where it started. 
 
We had several other large fractures in similar steep terrain.  The third picture shows a crack that opened up several inches but 30 feet wide.   The slab did not break loose due to the stiffness of the slab in the area.  We had seen enough signs of avalanches by this time and we moved to safer , less committing terrain.
 
We also had several shallower slabs break loose in steep terrain.  These were limited to 10 feet wide and only 6-8 inches deep traveling a total of 150 vertical feet (see picture 4)   
 
While approaching one of our lines we felt the entire snowpack settle but we did not notice any cracks.
 
There were also wet point release avalanches on East facing slopes in the morning as seen in Picture 5.  I am sure there were many more on south and west faces throughout the day.   

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