Good morning. This is Doug Chabot with the Gallatin National Forest Avalanche Advisory issued on Wednesday, February 20 at 7:30 a.m. Gallatin Country Search and Rescue in partnership with the Friends of the Avalanche Center sponsor today’s advisory. This advisory does not apply to operating ski areas.
BRIDGER PEAK AVALANCHE
A skier was caught, partially buried and injured in an avalanche on the east side of Bridger Peak, about 1/3 of the way down the face. He jumped a small cliff band and triggered the slope on landing. The avalanche was estimated to be a few hundred feet wide, a few feet deep and ran 5-600 feet into a confined gully. He was buried in a standing position and was able to free an arm and create an air space. Two of his partners booted up and dug him out while a third stayed out of the path and acted as an avalanche guard to warn of further slides. He suffered a leg injury and was flown by Gallatin County Search and Rescue to the hospital. Two pictures of the crown and path are online. We plan on investigating the avalanche today.
Since yesterday morning a trace to one inch of snow fell in the southern mountains. Under clear to partly cloudy skies temperatures are in the teens and winds are eerily calm. Clouds will increase today with light northwest winds and temperatures in the low twenties. Scattered snow showers will drop 1-2 inches tonight.
Bridger Range Madison Range Gallatin Range
Lionhead area near West Yellowstone
There have been avalanches or signs of instability reported every day since Friday. Besides the avalanche on Bridger Peak, four snowmobilers in Lionhead on Sunday were searching for the last scraps of untracked powder when they triggered a slide catching all of them (photo). Two riders deployed their airbags and everyone was uninjured.
From the Bridger Range to West Yellowstone, snow depths may vary, but the culprit creating these instabilities are buried facets. In thinner spots these are found 2 to 3 feet deep on the ground, while in deeper areas they are located midpack. Yesterday, Mark rode and dug along Buck Ridge. On most slopes he found weak snow in the lower half of the snowpack and his stability tests showed lingering problems (snowpit). Conditions are not “green light” or “go for it”, here or anywhere else.
Assessment of snow stability is tricky and serious. As we can see with wall to wall tracks, the snowpack is not hair trigger. In fact, most people can blindly ski or snowmobile around and return unscathed. Natural avalanches are not happening; cracking and collapsing are not found on many slopes; the recent avalanches might be miles away from your intended line. But do not fool yourself into thinking everything is honkey dory. I call these conditions a “scary” Moderate. This is when our travel advice follows the recommendations under a Considerable danger (“careful snowpack evaluation…”), but the likelihood of avalanches along with their size fit into a Moderate danger (“human triggered possible…naturals unlikely”). For today, the avalanche danger is rated (scary) MODERATE.
Cooke City
Yesterday there were two human triggered avalanches outside Cooke City. These are on the heels of slides on Saturday (photo) and Monday (photo). A skier took a long, nasty ride down an east facing couloir off Miller Ridge yesterday when the cornice he was standing on broke and triggered a slide. He was not buried and sustained minor injuries. Also yesterday, sledders triggered a slide on a southwest facing slope in Sheep Basin where there was a thin snowpack (photo). These avalanches are breaking on facets in shallow areas or on a thin layer of facets sitting on an ice crust 1-2 feet deep. All this avalanche activity is causing me deep concern. Bulls-eye data is not to be trifled with. My uncertainty level about stability is higher than I want, so I’m being conservative in my danger rating and folks should be conservative in their travel habits. The avalanche danger is rated CONSIDERABLE on all slopes steeper than 35 degrees and MODERATE on all other terrain.
Mark will issue the next advisory tomorrow morning at 7:30 a.m. If you have any snowpack or avalanche observations drop us a line at mtavalanche@gmail.com or call us at 587-6984.
AVALANCHE READING (Articles Page)
Accident report by Mark Staples, from an avalanche on Alex Lowe Peak, February 9.
Sidecountry is Backcountry, printed in the February issue of Carve, by Doug Chabot.
Know Your Slope Angles, printed in the February Montana Snowmobile Association Newsletter, by Eric Knoff.