Skier Triggered Slide - Backside Big Mtn
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09 Nov 2009
We received a report today of a skier triggered avalanche occurring
sometime recently on the backside of Big Mountain. The time of
the event was likely late last week or early this weekend, 11-5-09 to
11-7-09. The
failing layer was wind loaded snow on a northerly aspect near the top
of the mountain. Wind slab was lying upon a melt-freeze base of
previously wetted snow that has subsequently frozen into ice. The
size of the slide was such that it could have shallowly, but
totally, buried a person. Chances were more likely however,
of trauma injury, colliding with trees or other objects. We
have no official, first-hand report of the incident, so assume that
injuries were minor at worst.
This incident joins with two other early season events reported
elsewhere in Montana in late October- early November.
http://www.mtavalanche.com/accident/09/11/03-0
http://www.missoulaavalanche.org/pdf/gem_lake_avalanche_102409.pdf
These incidents all have some commonalties:
--Early season, with a relatively shallow snowpack
--Isolated pocket of mostly wind-loaded snow
--Recognition in at least two incidents that
instability existed
--In spite of a low chance of asphyxia, a
significantly high chance of trauma injury or death from
straining through talus, rock outcrops, trees, etc.
From the time of the falling of the first snow crystal to the melting
of the last ice grain it is imperative that we constantly keep snow
stability and avalanche safety in the front in our minds, screaming in
our ears and dangling in front of our eyes. Never let your
enthusiasm blind you to the threats present. Although not likely
fatal, all three of the incidents could have spelled the end of
someone's skiing or snowboarding experience for the season, or even a
lifetime. Bullets were dodged, but not by skill or design, only
by luck.
Be safe out there!!!!!
Stan Bones - USFS / Flathead National Forest
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