Sunday, December 11, 2016

Ski Season Is Here (Avalanche Season Too)

It's here, it's now and it's real. After a mostly fair and unseasonably warm November, to the delight of local snowshoe trekkers, cross country and alpine skiers, ice climbers and snowmobile enthusiasts, winter has descended onto us hard and fast in the weeks following Thanksgiving. 

The local ski area, Bridger Bowl, opened to excited crowds Friday. The skiing is delightful, as attested to by the opening day video.

Here are today's conditions.

Settled Basen/a31"
Seasonal Snowfall
(since Nov 1)
Snow Conditions
Water Content
Primary SurfacePowder
Secondary SurfacePacked Powder

Intrepid extreme skiers are hiking to The Ridge (search beacon transponders and shovels required) from where they can shoot down rocky chutes and tree-lined seams.

Webcam screenshot capture on the Ridge above Bridger Bowl, elevation 8,500 feet, December 11, 2016.

As the snow piles up, avalanche dangers also advance.

The Gallitan National Forest Avalanche Center has issued it's first set of warnings, blanketing close to 5,000 square miles.

Yesterday we had our first serious avalanche incident of the season.

Snowpack and Avalanche Discussion: 
Bridger Range   Madison Range   Gallatin Range
Lionhead area near West Yellowstone   Cooke City 
Yesterday in the Northern Madison Range, a snowmobiler was caught and fully buried in an avalanche in the second Yellowmule on Buck Ridge. He was located with an avalanche beacon by his partners and was uncovered with minimal injuries for a fortunate outcome. This event highlights the importance of being prepared with the right gear and the right partners. The avalanche likely broke on a layer of weak sugary snow above an ice crust on the ground (photo) and was on a heavily wind loaded slope.
Snowfall totals since Thursday equal 1” of snow water equivalent (SWE) throughout our advisory area with over 1.5” of SWE in the southern ranges. Strong winds yesterday transported new snow into fresh drifts near ridgelines and increased the stress on buried weak layers (video). Wind slabs and new snow slabs may rest over weak snow that formed on the surface during last week’s cold temperatures, and could be easy to trigger today. Avoid steep terrain if you see fresh wind slabs or cracking and collapsing in the new snow.
New snow and wind-loading also added weight to a layer of weak facets near the ground (videovideovideo). Ski patrols triggered avalanches on this layer over the last week (photophoto); and avalanches failed on this layer in the backcountry, including the one that caught and buried a snowmobiler yesterday on Buck Ridge. Wind loaded slopes will be the most likely place to trigger an avalanche on this layer, but avalanches are also possible on this layer on non-wind loaded slopes. Choose terrain with lower consequences and dig a hole to look for this layer before committing to steep terrain.
Recent snow and strong winds create unstable conditions today and the avalanche danger is rated 
Here is the Avalanche Center's December 10 video documenting forces that lead to avalanche.

In this blog we have documented again, and again, and again, and again the deadly impacts of avalanche. 

Please have fun and be careful out there. 

Update 12/11/16:

Not eight hours after posting this the Avalanche Center tweeted:


Update 12/12/16:

Some more details reported today.
Officials have identified the skier who died Sunday afternoon in an avalanche north of Cooke City.
Christopher Peterson, 55, of Ketchum, Idaho, was killed after being buried in an avalanche on the north slope of Henderson Mountain.
The avalanche was reported to be 6 feet deep and 100 feet wide, according to the Gallatin National Forest Avalanche Center.
Peterson, who was skiing with six others, was completely buried and located at the base of a tree with a transceiver by members of his party, the Avalanche Center said in a statement posted to Facebook.
They dug Peterson up within 15 to 20 minutes, but could not resuscitate him with CPR. When rescuers arrived, they took over and tried an AED to revive Peterson, but he was pronounced dead.
Another skier was partially buried but wasn’t hurt.

Here is Avalanche Center video from the scene with the complete story.

And this finding from the Avalanche Center:

Yesterday, Eric and I investigated the avalanche that killed a skier on Henderson Mountain outside Cooke City. The skier was in a party of 5 and his descent was the 7th track on the slope when it avalanched. He was carried into the trees and buried under 5’ of snow. Another person was buried to his waist, uninjured, as he stood in the runout zone. The victim was found with avalanche transceivers and dug up in 15-20 minutes. CPR was initiated, but unsuccessful as trauma was a likely factor in his death. The slope was only 250 vertical feet, but steep, averaging 40 degrees. The crown was 3’ deep and the path was 150’ wide. The avalanche broke on a layer of weak, sugary facets sitting on an ice crust 1’ above the ground. 

Our deepest sympathy goes out to his family and friends and his Ketchum, Idaho community.

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