GNFAC Avalanche Advisory for Mon Mar 12, 2018
<p>The mountains near Cooke City received 7-10” of snow at the end of last week, which was drifted into wind slabs by strong southwest wind on Friday. On Saturday, a skier on the Fin triggered a 1-2’ deep wind slab and was partially buried (<a href="https://www.mtavalanche.com/images/18/skier-triggered-wind-slab-fin"><s…;). They also reported another similar sized slide later in the day (<a href="https://www.mtavalanche.com/images/18/skier-triggered-wind-slab-near-co…;). These 1-2’ thick drifts are possible to trigger on shady wind loaded slopes, where the snow surface is dry and did not form a crust from sun and warm temperatures yesterday (<strong><a href="https://www.mtavalanche.com/images/18/wind-slabs-near-cooke-city">photo…;). Be cautious of wind loaded slopes and keep a far distance from the edge of large cornices and avoid slopes below. Avalanche danger today is <strong>MODERATE</strong> on wind loaded slopes and <strong>LOW</strong> otherwise.</p>
<p>In the mountains near Bozeman, Big Sky and West Yellowstone, warm weather and a lack of snow and wind allowed recent instabilities to gain strength and the snowpack is generally stable (<a href="https://youtu.be/0jpDHOgb7Hs"><strong>video</strong></a>). Large cornices along ridgelines are the main avalanche concern (<a href="https://www.mtavalanche.com/images/18/big-cornices-bear-basin"><strong>…;, </strong><a href="https://www.mtavalanche.com/images/18/large-cornices-bridger-range"><st…;). Cornices can break unexpectedly and farther back than anticipated. On Saturday, a cornice broke naturally and triggered an avalanche in the Hourglass chute north of Bridger Bowl (<a href="https://www.mtavalanche.com/images/18/cornice-triggered-avalanche-hourg…;, <a href="https://www.mtavalanche.com/images/18/cornice-triggered-hourglass-chute…;). Keep a far distance back from the edge of ridgelines and avoid slopes directly below large cornices.</p>
<p>Avalanche danger today is <strong>LOW</strong>. This means small and isolated avalanches can be triggered (<a href="https://youtu.be/u6E7gqjb9X0"><strong>video</strong></a>). Last Wednesday, a snowmobiler triggered and escaped an avalanche in the southern Madison Range (<a href="https://youtu.be/yrjwILDWCJE"><strong>video</strong></a>, <a href="https://www.mtavalanche.com/accident/18/03/10"><strong>accident report</strong></a>). The snowpack lacks widespread weak layers, but digging to assess structure and stability is recommended before riding in avalanche terrain.</p>
<p><strong><em>WET AVALANCHES</em></strong> will be minimal today as surface crusts soften slowly, but can be triggered on steep, sunny slopes when crusts melt. They can occur naturally around rock outcrops and below cliffs. Be cautious of steep, sunny slopes if you see rollerballs or natural wet loose slides (<strong><a href="https://www.mtavalanche.com/images/18/wet-loose-avalanche-ross-peak">ph…;, <strong><a href="https://www.mtavalanche.com/images/18/wet-loose-avalanches-beehive">pho…;).</p>
<p>If you get out and have any avalanche or snowpack observations to share, drop a line via our <a href="https://www.mtavalanche.com/node/add/snow_observation">website</a>, email (<a href="mailto:mtavalanche@gmail.com">mtavalanche@gmail.com</a>), phone (406-587-6984), or Instagram (#gnfacobs).</p>
Upcoming Avalanche Education and Events
LIVINGSTON
March 20, Beer for a Cause Night at Katabatic Brewing, 4-8p.m. A dollar from every pint will be donated to The Friends of the Avalanche Center.
Weather and Avalanche Log for Mon Mar 12, 2018
Temperatures reached 40F.
As temperatures continue to rise, so do the odds of encountering wet loose avalanches on solar aspects. Rollerballs and pin wheels indicate that the snow surface is getting wet and losing strength. Photo: G. Antonioli
Forecast link: GNFAC Avalanche Advisory for Mon Mar 12, 2018
GNFAC Avalanche Advisory for Sun Mar 11, 2018
<p>Yesterday, a skier triggered a wind slab and was partially buried on the Fin near Cooke City (<strong><a href="https://www.mtavalanche.com/images/18/skier-triggered-wind-slab-fin">ph…;). The slide broke 1-2’ deep as the group skinned uphill on a steep rollover. It was 250’ wide and ran 200’ into dense trees. The same group triggered another similar sized slide later in the day, and they reported ‘touchy’ conditions (<strong><a href="https://www.mtavalanche.com/images/18/skier-triggered-wind-slab-near-co…;).</p>
<p>Strong southwest wind accompanied the end of the storm Friday, and 7-10” of new snow was drifted into 1-2’ thick wind slabs that are possible to trigger. Be cautious of steep, drifted slopes found near ridgelines, cliffs, and steep rollovers (<strong><a href="https://www.mtavalanche.com/images/18/wind-slabs-near-cooke-city">photo…;). Keep a far distance from the edge of massive cornices, and avoid slopes directly below. Strong wind Friday formed widespread wind slabs that are possible to trigger and avalanche danger today is <strong>MODERATE</strong>.</p>
<p>Slopes that receive direct sun will have a surface crust this morning, which will minimize wet snow avalanches. If the crust softens or you see rollerballs and natural wet loose slides, be cautious of steep, sunny slopes.</p>
<p>Near Bozeman, Big Sky and West Yellowstone the snowpack is generally stable (<a href="https://youtu.be/0jpDHOgb7Hs"><strong>video</strong></a>), but small and isolated avalanches can be triggered. Yesterday, skiers saw a cornice triggered avalanche in the Hourglass chute north of Bridger (<strong><a href="https://www.mtavalanche.com/images/18/cornice-triggered-avalanche-hourg…;, <strong><a href="https://www.mtavalanche.com/images/18/cornice-triggered-hourglass-chute…;). Last Wednesday, a snowmobiler triggered and escaped an avalanche in the southern Madison Range. See <strong><a href="https://youtu.be/yrjwILDWCJE">video from Eric’s visit</a></strong> to the avalanche site and our <strong><a href="https://www.mtavalanche.com/accident/18/03/10">accident report</a></strong>.</p>
<p>Huge cornices cling to the edge of ridgelines (<a href="https://www.mtavalanche.com/images/18/big-cornices-bear-basin"><strong>…;, </strong><a href="https://www.mtavalanche.com/images/18/large-cornices-bridger-range"><st…;), and can break unexpectedly and farther back than anticipated. Keep a far distance from the edge of ridgelines and minimize time below. Also keep an eye out for small wind slabs that may be harmful in consequential terrain. On sunny slopes, wet loose avalanches can be triggered if the crust on the snow surface melts later in the day. The snowpack lacks widespread weak layers, but digging to assess structure and stability is recommended before riding avalanche terrain.</p>
<p>Avalanche danger today is <strong>LOW</strong>. There are still hazards to watch for during low danger, as highlighted in my recent <a href="https://youtu.be/u6E7gqjb9X0"><strong>video</strong></a><strong> </strong>from Friday.</p>
<p>If you get out and have any avalanche or snowpack observations to share, drop a line via our <a href="https://www.mtavalanche.com/node/add/snow_observation">website</a>, email (<a href="mailto:mtavalanche@gmail.com">mtavalanche@gmail.com</a>), phone (406-587-6984), or Instagram (#gnfacobs).</p>
Upcoming Avalanche Education and Events
LIVINGSTON
March 20, Beer for a Cause Night at Katabatic Brewing, 4-8p.m. A dollar from every pint will be donated to The Friends of the Avalanche Center.
Wind slabs 1-2' thick were triggered by skiers on Saturday 3/10. These are good examples of wind loaded slopes on cross-loaded features.
Forecast link: GNFAC Avalanche Advisory for Sun Mar 11, 2018
A skier triggered and was partially buried in this avalanche on Republic Mountain on Saturday 3/10. From e-mail:
Wind slab being triggered on Mt. Republic on Saturday 3/10. Skiers reported touchy conditions, and another skier triggered and was partially buried in a similar sized slide to this one.
Debris of cornice avalanche in the Hourglass chute north of Bridger Bowl that was triggered by a passing skier. Slid on Saturday 3/10. Strong wind has loaded huge cornices to a breaking point. Photo: K. Casperson