Observation: Turnagain

Below is a look at the human triggered avalanche on Magnum from 12/22, Sunday.

This was a short running avalanche that propagated quite wide. It was on the
common steep roll at the bottom of the Northwest (or often just called the West)
face of Magnum facing the road.

Avalanche details:
Human triggered soft slab – is unclear if this was remotely triggered.
Northwest facing
2400′ elevation
12-14″ deep
300′ wide
90′ vertical
Weak Layer: Facets/decomposing fragments above the December ‘drizzle’ crust
Slab: 12-14″ of 4finger hardness snow from all our December storms

Of interest is the smooth but dramatic change in slope angle in just a few feet
on this rollover – from 30 to 45 degrees. You can see in the picture the curve
of the snow over the convexity and the resulting break of the slab at this
point. This is of course text book but still cool to see in a cross section.

Also, some of the November snow (that is now the weak faceted snow below the
slab) was scoured away by winds before the drizzle crust was laid down (Dec
7/8). You can also see this in the crown photo below. There is a thicker layer
of older snow under the slab that thins over the convexity and under the bed
surface.