Tuesday, December 2, 2014

Avalanche Advisories Issued

It's that time of year again. Beware the avalanche.

There has already been a fatality. A snowmobiler from North Dakota perished near Cooke City.
A 31-year-old snowmobiler from North Dakota died Wednesday after being buried in an avalanche in the Henderson Peak area near Cooke City.
The Park County Sheriff’s Office received a report at about 1:30 p.m. of an individual partially buried and not breathing.
Search and Rescue members were dispatched from Cooke City, according to a release from Undersheriff Scott Hamilton.
According to another release, the man had been riding with a friend about 100 yards off the trail when the avalanche occurred.

The 31-year-old man was reportedly buried in about 7 feet of snow. He and his riding partner both had avalanche beacons.

The friend located and unburied the man, which took about minutes 20, and performed CPR.
Here is the Gallitan National Forest Avalanche Center's warning for Cooke City.

Cooke City
The mountains around Cooke City received .6” of SWE last night with strong winds. Over the last nine days this zone was hit hard with storms and avalanches. Steady snow will help the stability in the long-term, but not the short-term. The immediate problem is a weak layer of facets on the ground that started avalanching after the storms dropped almost 3” of SWE (a couple feet of high density snow) since the weekend before Thanksgiving. The weak layer was very active then and will be less reactive now, but by no means is it stable. Red-flag warnings like cracking and collapsing of the snow are becoming rarer, but triggering a slide on skis or a snowmobile is still likely if you venture into avalanche terrain.
Last Wednesday’s avalanche fatality (videoreport) and a seven foot burial on Friday (yes, he lived) are irrefutable evidence that the avalanche danger is real. Given the poor snow structure and recent snow and wind the avalanche danger is rated CONSIDERABLE today.

Here is the video.

The avalanche center has issued warnings for other nearby ranges.

Bridger Range   Gallatin Range   Madison Range  
Lionhead area near West Yellowstone  
A poor snow structure plagues all the mountain ranges in our forecast area (snowpits). Weak, faceted snow at the ground is still misbehaving. On Sunday, Eric got widespread cracking and collapsing in Beehive Basin in the northern Madison Range (video) while I had similar experiences in the Bridger Range at Fairy Lake (video). Yesterday, the Big Sky Ski Patrol triggered avalanches with explosives which are relevant because these slopes have a backcountry snowpack and this is the first time they’ve been tested. 
Strong winds have been loading slopes near the ridgelines as well as cross-loading in gullies. Weak snow at the ground is still unstable, especially on steep slopes. For today, the avalanche danger is ratedCONSIDERABLE on all slopes steeper than 35 degrees and MODERATE on all others.

Here is the Fairy Lake video.

Be careful out there. For advice on how to prepare for avalanches in the event you are unexpectedly overtaken, go to our post January post. We don't want to write this winter on any more of our children's classmate's parents buried in and perishing in the snow.

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