Explosive triggered deep slab at Big Sky

Big Sky Resort
Northern Madison
Code
HS-AEc-R4-D3.5-O
Elevation
9800
Aspect
SE
Latitude
45.27260
Longitude
-111.44700
Notes

From BSSP: "The avalanche factory that is The Wave did indeed go into production today. A 2lb. shot in skier’s right Castro’s Shoulder initiated an impressive deep slab avalanche that took out Castro’s Shoulder through Wave South above Vuarnet Cliffs. The secondary start zones under these paths- Castro’s Beard (south half) and Mike’s Rodeo- also avalanched away.

The bed surface appears to be the top of the original big storm in October that forms the base of the snowpack on Lone Mountain. There is a melt/freeze crust at the top of that layer, with
small grained (mostly) facets on top of the crust, with the rest of the season’s snowpack sitting on that weak
interface.  

This [wide] propagation may be the result of the surface wind slab formed in the past few days finally tying the paths together enough to allow for such propagation.

The numbers are impressive- estimated crown length of 1,100 ft., crown depth of 3-4’, vertical run
of 1000 ft., and linear run of 2000 ft. We classified the slide as HS, AE (2lb.), R4/D3.5, O/G. Unfortunately,
conditions rendered good photos difficult. All the paths that avalanched have been shot repeatedly, almost
daily, all season long...."

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Hard slab avalanche
Trigger
An explosive thrown or placed on or under the snow surface by hand
Trigger Modifier
c-A controlled or intentional release by the indicated trigger
R size
4
D size
3.5
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness
42.0 inches
Vertical Fall
1000ft
Slab Width
1100.00ft
Weak Layer Grain type
Faceted Crystals
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year