Weather and Avalanche Log for Tue Mar 27, 2018
Very windy in Bridgers (40-50 mph, G70 mph) at all elevations and directions.
17-18
South of Cooke City, a recent slab avalanche up Republic Creek from Monday (3/26). A wind loaded, north facing slope around 9,700'. Photo: B. Fredlund
Forecast link: GNFAC Avalanche Advisory for Tue Mar 27, 2018
A cornice fall triggered this avalanche on Lionhead Ridge that broke sometime late Saturday (3/24). Photo: B. Rasmussen
GNFAC Avalanche Forecast for Mon Mar 26, 2018
Snowpack and Avalanche Discussion
<p>Today is another spring day with an array of avalanche problems to watch for. The primary concern is wind loaded slopes. Heavy new snow and strong wind on Saturday formed 8-12” deep slabs near ridgelines, along the base of cliffs and on steep convex terrain (<a href="https://youtu.be/GgZtfI4E2DQ"><strong>video</strong></a>, <a href="https://youtu.be/iaHHEql8ZwU"><strong>video</strong></a>). A natural wind slab was observed yesterday on Saddle Peak (<strong><a href="https://www.mtavalanche.com/images/18/wind-slab-avalanches-saddle-peak"…;), and on Saturday skiers easily triggered 6-10” deep wind slabs in Beehive Basin (<strong><a href="https://www.mtavalanche.com/images/18/skier-triggered-slides-beehive-ba…;). Yesterday, the Big Sky ski patrol triggered a 3-5’ deep slab in a heavily wind loaded pocket (<strong><a href="https://www.mtavalanche.com/images/18/explosive-triggered-wind-slab-cro…;). Wind slabs have gained strength, but remain possible to trigger today. Wind loaded slopes should be approached with caution or avoided.</p>
<p>Loose snow avalanches are possible on slopes that have dry new snow on the surface this morning. Yesterday near Cooke City, skiers saw loose slides run naturally when the sun came out, and they triggered a 16” deep soft slab. Today, below freezing temperatures and mostly cloudy skies will hinder wet loose avalanche activity. However, any periods of sunshine will make loose avalanches possible to trigger or run naturally on steep, sunny slopes. Avoid steep slopes if the dry new snow becomes moist or wet (<strong><a href="https://youtu.be/-cvHq-7k_EQ">video</a></strong>), or if it slides easily on small test slopes (<strong><a href="https://www.mtavalanche.com/images/18/small-sluff-above-tree-well">phot…;). Be aware of possible avalanche terrain overhead where natural loose slides can initiate, such as sunny rock outcrops or around cliffs (<strong><a href="https://youtu.be/W_mcy_fnF44">video</a></strong>).</p>
<p>Lastly, cornices are massive along ridgelines and can break under the weight of a person and farther back than expected (<strong><a href="https://www.mtavalanche.com/images/18/cornice-fallcentennial-mtns">phot…;). Keep a far distance back from the leeward edge of ridgelines and avoid slopes directly below huge cornices.</p>
<p>Recent new snow and wind, and possible spring sunshine today make avalanches possible and avalanche danger is MODERATE. Aside from recent snow, wind slabs and large cornices, the snowpack is generally stable and deeper slides are not likely.</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>
Cornice Fall, Centennial Mountains, ID
On Tuesday, March 20, a snowmobiler walked to edge of the ridge and broke a
Reactive snow on steep edge of tree well. Sluffing or cracking on small rolls and micro-terrain features is a sign that loose slides or soft slabs are possible and may run far on larger, steep terrain. Photo: H. Coppolillo
Big Sky ski patrol triggered this slide with explosives on Sunday (3/25). It is in a heavily wind loaded pocket. Heavy snow and strong wind formed fresh slabs on Saturday. Many have gained strength, but are possible to trigger for a day or two. Photo: BSSP
Big Sky ski patrol triggered this slide with explosives on Sunday (3/25). Heavy snow and strong wind formed fresh slabs on Saturday. Many have gained strength, but are possible to trigger for a day or two. Photo: BSSP
Forecast link: GNFAC Avalanche Forecast for Mon Mar 26, 2018