Snowpack and Avalanche Discussion
<p><span><span><span><span><span><span>Snowfall totals since Friday are 4-9” of low density snow (0.3-0.5” snow water equivalent), and Ian and Dave found up to 16” (0.7” SWE) in the Centennials near Island Park yesterday (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=_Q_YPhkGuQk&list=PLXu5151nmAvSH326z…;, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/29813"><span><span><span><strong><span…;). Overall not the most impressive multiple day storm totals, but enough to improve general travel, riding and skiing conditions, and enough to increase avalanche danger. </span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Winds have been calm to light and our observations from yesterday note the low density snow has not posed a major hazard, but that will change today. Winds will increase enough to drift the recent snow into stiffer slabs. These slabs will easily avalanche under the weight of a person because they sit on a very weak snowpack that exists on most slopes throughout our advisory area (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/24/snowpit-head-hellroaring-creek"><… near I.P. photo</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/24/snowpit-second-yellowmule-jan-6">… Ridge snowpack photo</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). I saw this weak snowpack the last couple days near Big Sky and in the Bridgers (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=BUYSrxrZqyc&list=PLXu5151nmAvSH326z…;), and on Saturday at Buck Ridge just a couple inches of snow and a few hours of wind were enough to create widespread avalanche activity (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=Y0LROtnc7Us&list=PLXu5151nmAvSH326z…;, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/29809"><span><span><span><strong><span… and observation</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>).</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>On slopes without wind loading the weak snowpack is capable of producing large dry loose avalanches on long, sustained steep slopes (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/24/dry-loose-avalanches-weak-facets"… from Buck Ridge</span></span></u></span></strong></span></span></span></a><span><span><span><strong><span><span>, </span></span></strong></span></span></span><a href="https://www.mtavalanche.com/images/24/skier-triggered-loose-snow-avalan… from Beehive</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/24/loose-snow-avalanche-henderson"><… from Cooke</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). These ”facet sloughs” can be started by a skier or rider pushing on the slope, or from a small wind slab or loose avalanche of new snow from above. They carry plenty of force to knock you over as they entrain almost the entire snowpack. On Saturday we saw a few of these dry loose slides and easily triggered a few fresh wind slabs (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=Y0LROtnc7Us&list=PLXu5151nmAvSH326z…;, </span></span></strong></span></span></span><a href="https://www.mtavalanche.com/node/29802"><span><span><span><strong><span… slab photos</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>).</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Watch for signs of recent wind-loading such as cornices, rounded smooth pillows of snow and snow surfaces with wavy textures. Cracking across the surface of the snowpack is a sign you have found an unstable drift that will slide on steep slopes. Because of the very weak snowpack, avalanches may break above you, or wider or larger than expected. Any size slide can get you into trouble if it carries you into trees, over cliffs or rocks, or piles up deeper in a confined gully. If you have any doubts, choose routes that avoid slopes steeper than 30 degrees and the runout zones below. Today the avalanche danger is CONSIDERABLE on wind-loaded slopes and MODERATE on non-wind-loaded slopes throughout the forecast area.</span></span></span></span></span></span></p>
Upcoming Avalanche Education and Events
Our education calendar is full of awareness lectures and field courses. Check it out: Events and Education Calendar.
