Skier triggered avalanche 3D Chute - Dream Mtn - Negatives

AVALANCHE OBSERVATION
3D Chute

Drainage:

Submission Info
josh feinberg
Forecaster
Tuesday, February 19, 2019 - 12:30pm
Red Flags: 
Recent loading by new snow, wind, or rain
Avalanche Type: 
Dry
Slab
Slope: 
50degrees
Trigger type: 
Skier
Crown Height: 
3 ft
Aspect: 
East
Weak Layer: 
Storm Snow
Avalanche Width: 
40ft.
Terrain: 
Above Treeline
Elevation: 
10 750ft.
Bed Surface: 
Old Snow
Avalanche Length: 
1 400ft.
Number of partial burials: 
1
More detailed information about the avalanche: 

An anonyous report of human triggered avalanche in 3D chute in the negatives area behind June Mtn that occured on Feb 19th around 12:30pm:

"A member of our 4 person party set-off and was caught in an avalanche yesterday in the San Joaquin/June/Negatives area, in what is popularly known as 3D chute. Others started slides in our runs as well in similar elevations. These fractures appeared to go down to the same rain/melt-freeze/ice layer.  Very soft slab released, that left the entire chute with a barren exposed rain/ice crust.

These are my observations. I was at the drop-in with the skier/snowboarder who triggered the avalanche and I witnessed the break from above. 
 
Weather: Sunny, light upslope wind, temp 10-20 degrees. 
Snow: wind/storm deposited light powder
Aspect: East SE facing chute
Slope: 50-55 degree
Elevation: 10,750 ft
Avalanche size: R3*/D2*
2-3'+ crown/40' wide 
1400' vertical slide
 
Skier/snowboarder triggered the slide about 20 feet down in his 2nd or 3rd turn.  I witnessed snow moving to his periphery and above him as he was engulfed and then carried down the entire chute onto the bottom apron, about 1400 feet below. He was able to free himself from only partial burial and ride away with no major injury.
 
As a sidenote, It seemed possible that this chute slide naturally previously during the main storm event on this icy layer, and was filled back in with light wind deposited snow.
Avalanche Photos: 
Number of People Caught: 
1
37° 44' 4.3512" N, 119° 5' 48.7356" W
See map: Google Maps

ESAC receives significant financial support from ...