19-20

Small snowmobiler triggered avalanche in McAtee Basin. From Instagram: "I watched a snowmobiler set this avalanche off today" T. Chamberlain

Northern Madison, 2020-01-21

GNFAC Avalanche Forecast for Tue Jan 21, 2020

Snowpack and Avalanche Discussion

<p>This weekend skiers, riders, new snow, and cornice falls triggered seventeen avalanches in the Bridger and Madison Ranges, and the mountains around Cooke City and West Yellowstone. There were two close calls yesterday when snowmobilers unintentionally triggered avalanches that broke on deeply buried weak layers in the Buck and Lionhead Ridge areas (<strong><a href="https://www.mtavalanche.com/node/21707">avalanche activity</a>). </strong>The rider in Lionhead stated, " Our group is trained in avalanche safety, practiced beacon use prior to leaving town in the morning, were wearing avalanche gear, and were very fortunate that this ended the way it did" (<strong><a href="https://www.mtavalanche.com/node/21706">avalanche activity</a></strong>). We added these incidents to our <strong><a href="https://www.mtavalanche.com/avalanche-activity">avalanche log</a> </strong>that includes a 10-foot deep snowmobile triggered slide on Cedar Mountain (<a href="https://www.mtavalanche.com/node/21678"><strong>details</strong></a&gt;), a skier triggered avalanche north of Bridger Bowl (<a href="https://www.mtavalanche.com/node/21672"><strong>details</strong></a&gt;), and natural avalanches near Lionhead Ridge and Cooke City (<a href="https://www.mtavalanche.com/images/20/natural-avalanche-north-lulu-pass…;, </strong><a href="https://www.mtavalanche.com/node/21700"><strong>avalanche activity</strong></a><strong>)</strong>. We are grateful to everyone who sent in their incident reports this weekend. You help us learn and make safer decisions as a community.</p>

<p>Human triggered avalanches are less likely each day without new snow. Many riders or skiers will “get away with it” before an unlucky person triggers a potentially fatal avalanche. This is the reality of moderate danger on a year with widespread persistent weak layers as Alex and I discuss in our <a href="https://www.youtube.com/watch?v=TBygi0dYfQY&amp;list=PLXu5151nmAvSbcbVf…;. Doug explains in his <a href="https://www.youtube.com/watch?v=MsjmwmAH7Ww&amp;list=PLXu5151nmAvSbcbVf…; from Mount Abundance that thinner areas in the snowpack are the likely places a skier or rider can trigger one of these monster avalanches. The management strategy is avoiding steep terrain and an honest assessment of your personal risk tolerance. The avalanche danger is rated MODERATE with large, human triggered avalanches possible.</p>

<p>The Shower Falls Snotel reported only 10” of new snow in the last week, but wind gusts of up to 65 mph were enough to build large, dense slabs of snow. On Saturday, skiers unintentionally triggered three separate avalanches in the Northern Gallatin Range, the largest broke up to 7 feet deep on buried weak layers (<a href="https://www.mtavalanche.com/node/21638"><strong>details</strong></a&gt;, <a href="https://www.mtavalanche.com/node/21655"><strong>details</strong></a><st…;, </strong><a href="https://www.mtavalanche.com/node/21650"><strong>details</strong></a&gt;). These were the first large slides of the year reported in this area. Yesterday on a tour to Divide Peak, we found a generally stable snowpack outside of areas with heavy wind loading (<a href="https://www.youtube.com/watch?v=adAes9pGEy0&amp;list=PLXu5151nmAvSbcbVf…;). Give fresh drifts of snow time to stabilize by avoiding steep slopes loaded by the wind. Assess the snowpack and consequences of a small avalanche before committing to steep terrain. The avalanche danger is rated MODERATE on wind loaded slopes and LOW everywhere else.</p>

<p>If you get out, please send us your observations no matter how brief. You can fill out an&nbsp;<a href="https://www.mtavalanche.com/node/add/snow_observation"><strong>observat… form</strong></a>, email us (<a href="mailto:mtavalanche@gmail.com"><strong>mtavalanche@gmail.com</strong></a…;), leave a VM at 406-587-6984, or Instagram (#gnfacobs).</p>

Upcoming Avalanche Education and Events

Our education calendar is full of awareness lectures and field courses. Check it out and plan to attend one or two: Events and Education Calendar.

COOKE CITY

Every Friday and Saturday, Snowpack Update and Rescue Training. Friday, 6:30-7:30 p.m. at the Soda Butte Lodge. Saturday anytime between 10-2 @ Round Lake.

BOZEMAN

From email:

"I wanted to make you aware of a snowmobile triggered slide in Lionhead today. Fortunately, I was not injured, was able to stay completely on top, climbed through the majority of the snow wash after seeing it begin to break, and relatively slowly slid down with the last of the moving snow while still on the machine. When I came to a stop, I stood up and was completely free of the snow. Our group is trained in avalanche safety, practiced beacon use prior to leaving town in the morning, were wearing avy gear, and were very fortunate that this ended up the way it did. 

Lionhead Range, 2020-01-21