Snowpack and Avalanche Discussion
<p><a>A large snowstorm ended yesterday morning. Total snowfall was 14-20” that measured 1.5-2” of </a><a href="https://www.mtavalanche.com/taxonomy/term/451">snow water equivalent</a> (SWE) and created instability throughout our forecast area. Yesterday, avalanches released naturally and a few were human triggered. The full list is <a href="https://www.mtavalanche.com/avalanche-activity"><strong>here</strong></…;
<ul>
<li>In the Bridger Range many slopes sluffed naturally. One solo skier triggered a large loose-snow avalanche that carried him through trees. He was extremely lucky he wasn’t injured or buried.</li>
<li>A natural avalanche was seen on Saddle Peak.</li>
<li>A snowmobiler got a slope to fracture, but not slide, on Buck Ridge in the northern Madison Range.</li>
<li>Skiers above Quake Lake saw a couple natural avalanches in the new snow from wind-loading.</li>
<li>Skiers above Hebgen Lake experienced collapsing and poor stability test scores.</li>
</ul>
<p>All this activity occurred in the upper 2-3 feet of the snowpack on a weak interface of either an ice crust, feathery surface hoar, or small-grained facets. It really doesn’t matter which since they are all a similar depth and unstable. Dave and I found all three in the last week during field trips to Buck Ridge (<a href="https://youtu.be/l6eItO1yerM"><strong>video</strong></a>), Taylor Fork and Lionhead (<a href="https://youtu.be/ZkyjbN1sWl0"><strong>video</strong></a>). Yesterday we toured along the Bridger ridge and could easily sluff the new snow which would travel far once it stepped down to the ice crust (<a href="https://youtu.be/s5ED_1T3leE"><strong>video</strong></a>). In a few spots it broke as a soft slab, but did not propagate far. Stability tests are showing this weakness, so dig and test. More than one party kept to low-angled slopes after getting poor test scores.</p>
<p>There has been no new snow since yesterday morning and last night’s wind changed direction from west to east and lessened in speed. East wind is an unusual direction and will drift snow in unusual places. Overall the avalanche danger is less than yesterday, but there is still a strong possibility of triggering slides, most notably on wind-loaded slopes or steep terrain that has not sluffed. Cracking, collapsing and recent avalanche activity are bulls-eye information to avoid a slope, and we had all 3 in the last 24 hours. Do not let clearing skies and fresh powder give you a false sense the world is peachy. It is not.</p>
<p>For today, throughout our forecast area, the avalanche danger is rated MODERATE on all slopes.</p>
<p>Sunshine may dampen the snow surface, but wet avalanche activity is unlikely given the cold air temperatures.</p>
<p>We are ending daily avalanche forecasts this Sunday, April 5<sup>th</sup> and will post general weather and avalanche bulletins every Monday and Friday through April. Continue to send us your observations. You can fill out an <u><a href="https://mtavalanche.us17.list-manage.com/track/click?u=6653a830e4819c9e…; target="_blank">observation form</a></u>, email us (<u><a href="mailto:mtavalanche@gmail.com" target="_blank">mtavalanche@gmail.com</a></u>), leave a VM at 406-587-6984, or Instagram (#gnfacobs).</p>
Avalanche Education
See our calendar for a couple live online avalanche courses being offered this week.
