From obs 5/6/21: "This morning we went to... the Tobacco Roots. The dusting of snow in recent days had wind loaded northwest aspects, and created a wet loose hazard by the late morning (photo). We observed several wet slabs that went at the ground on southern aspects throughout the area (unfortunately unable to get a photo), and temperatures were nearing 60F before noon." Photo: E. Schreier
From email 5/2/21: "Small but plentiful wet snow avalanches in Cooke City today. Didn’t see any that were broke on a deeper scale."
From obs 4/30/21: "Yesterday I witnessed a big wet slide . It started on the exit from The Fin on Old Man Rays. Looks like it started on a rock band. Noon. Since people have been skiing The Fin recently I just happened to be looking up there and saw movement. It quickly quadrupled and then flowed across the ski line and over the cliff band. Spectacular. Flowed like a water fall for about a minute."
From email 5/2/21: "Small but plentiful wet snow avalanches in Cooke City today. Didn’t see any that were broke on a deeper scale." Photo: K. Goodyear
<h3><strong>GENERAL SPRING SNOWPACK AND TRAVEL ADVICE</strong></h3>
<p>NEW SNOW AND WIND LOADED SLOPES</p>
<p>Spring storms are notorious for depositing heavy amounts of snow in the mountains. Even with a deep and generally stable snowpack throughout the advisory area, heavy and rapid loads of new snow will decrease stability. The main problems to look out for are avalanches breaking within the new snow, wind slabs, and loose snow avalanches. The likelihood of triggering an avalanche spikes during and immediately after snowstorms. New snow instabilities tend to stabilize quickly, but it’s a good idea to give fresh snow a day to adjust before hitting big terrain. New snow instabilities can be challenging to assess, and spring storms bond to old snow differently across aspects and elevations. Conservative terrain selection is essential during and immediately following storms. Avoid wind-loaded slopes and slopes steeper than 35 degrees for 24-48 hours after new snow and wind.</p>
<p>New snow can quickly change from dry to wet on a spring day, and stability can decrease rapidly with above freezing temperatures or brief sunshine. New snow may bond well early in the morning and then easily slide later. Wet loose slides are likely during the first above freezing temperatures or sunshine immediately after a storm. Anticipate changes in snow stability as you change aspect or elevation and over the course of the day. An early start is always an advantage. Be ready to change plans or move to safer terrain at the first signs of decreasing stability.</p>
<p>WET SNOW AVALANCHES</p>
<p>Spring and wet snow avalanches go hand-in-hand. Above freezing temperatures, rain, and/or intense sunshine cause the snow to become wet and weak and make wet avalanches easy to trigger or release naturally. Conditions tend to become most unstable when temperatures stay above freezing for multiple days and nights in a row. Avoid steep terrain, and be aware of the potential for natural wet avalanches in steep terrain above you, if you see:</p>
<ul>
<li>Heavy rain,</li>
<li>Above freezing temperatures for more than 24 hours,</li>
<li>Natural wet avalanches,</li>
<li>Rollerballs or pinwheels indicating a moist or wet snow surface,</li>
<li>Or if you sink to your boot top in wet snow.</li>
</ul>
<p>In general, if the snow surface freezes solid overnight, the snowpack will be stable in the morning and stability will decrease through the day as snow warms up. The snow surface hardness, rate of warming, duration of sunshine, aspect and elevation determine how fast stability will decrease through the day. Be aware that sunny aspects may have a wet snow avalanche danger while shadier slopes still have a dry snow avalanche danger. Getting off of steep slopes should be considered when, or before, the above signs of instability are present. Wet snow avalanches, whether loose snow or slabs, can be powerful, destructive and very dangerous. Conservative terrain choices, starting early in the day, and careful observations can keep you safe.</p>
<p>CORNICES</p>
<p>Cornices along ridgelines are massive and can break under the weight of a person. Prolonged above freezing temperatures and rain make them weaker and possible to break naturally. They can break off suddenly and farther back than one might expect. Cornice falls can also entrain large amounts of loose snow or trigger slab avalanches. Stay far back from the edge of ridgelines and minimize exposure to slopes directly below cornices. Regardless of whether a cornice triggers a slide or not, a falling cornice is dangerous to anyone in its path.</p>
<p>DISCLAIMER</p>
<p>It does not matter if new snow falls or not, avalanches will continue to occur until the existing snowpack is mostly gone. Always assess the slope you plan to ride with diligence and safety in mind. Do not let your guard down. Travel with a partner, carry rescue gear and only expose one person at a time in avalanche terrain.</p>
<p>Have a safe and enjoyable spring and summer!</p>
<p>Doug, Alex, Ian and Dave</p>
<p>For more spring travel advice see this <a href="https://www.mtavalanche.com/blog/transitions-spring-snow-avalanche-prob… our GNFAC forecaster blog.</p>
<p>We will continue to share relevant avalanche and snowpack information on our website and social media when available. If you get out, please send us your observations no matter how brief. Submit them via our <a href="https://www.mtavalanche.com/node/add/snow_observation"><strong>website<…;, email (<a href="mailto:mtavalanche@gmail.com"><strong>mtavalanche@gmail.com</strong></a…;), phone (406-587-6984), or Instagram (#gnfacobs).</p>
Give Big Gallatin Valley is May 6th –7th. The Friends of the Avalanche Center are participating again this year and thank you for your support.
<p>Large wet slab avalanches are likely today and tomorrow. Temperatures are the warmest that this winter’s snowpack has felt, reaching 40s and 50s F the last few days and not dropping below freezing the last two nights. We received a report from someone who traversed the Bridger Range on Wednesday and saw multiple wet slides, some that broke a couple feet deep (<strong><a href="https://www.mtavalanche.com/node/24881">photos and details</a></strong>). As temperatures reach 60s F today, large wet snow avalanches will occur naturally, and will be easy to trigger if you travel on steep, snow-covered slopes. On Saturday afternoon, any steady rain in the mountains could trigger wet snow avalanches. Wet slides could remain possible to trigger on Sunday if the snowpack does not freeze Saturday night.</p>
<p>The weak, unconsolidated snowpack creates poor skiing and riding conditions and difficult travel. Don’t fight it, winter will return on Sunday. During these summer-like days while the deep, recently dry snowpack melts, consider off-snow activities or limit travel to low angle slopes. Get the bike out, maybe hit the river or crag. Regardless of your activity, minimize time spent underneath steep, snowy slopes even if the ground under your feet is dry.</p>
<p>Sunday and next week, conditions will be more appropriate for skis or a snowmobile. The snowpack will freeze most nights and avalanche concerns will involve new snow that falls, or small wet slides as the snow surface melts through each day. Avalanches will continue until the snowpack has melted. Remain diligent with careful snowpack assessment and cautious terrain selection. See below for additional general spring snowpack and travel advice.</p>
<p>Continue to share your avalanche observations. We will post them on our website/media to help each other stay safe. Thank you for your support and see you next fall. You can submit observations via our <a href="https://www.mtavalanche.com/node/add/snow_observation"><strong>website<…;, email (<a href="mailto:mtavalanche@gmail.com"><strong>mtavalanche@gmail.com</strong></a…;), phone (406-587-6984), or Instagram (#gnfacobs).</p>
Give Big Gallatin Valley is May 6th –7th. The Friends of the Avalanche Center are participating again this year and want to thank all of you for your support.
From obs: "I traversed the Bridger range yesterday (4/28/21). The alpine start was good and solid but I saw lots of recent avalanches that looked super wet, some that had broken a couple feet deep. Conditions were pretty stable until about 1300 when that most recent snow layer started to really want to s slide on the crust. Once I was in the meadows between Baldy and the M, at about 1400, I started hearing/feeling really wet "whumps".
From obs: "I traversed the Bridger range yesterday (4/28/21). The alpine start was good and solid but I saw lots of recent avalanches that looked super wet, some that had broken a couple feet deep. Conditions were pretty stable until about 1300 when that most recent snow layer started to really want to slide on the crust. Once I was in the meadows between Baldy and the M, at about 1400, I started hearing/feeling really wet "whumps". Photo: J. Harrison
From obs: "I traversed the Bridger range yesterday (4/28/21). The alpine start was good and solid but I saw lots of recent avalanches that looked super wet, some that had broken a couple feet deep. Conditions were pretty stable until about 1300 when that most recent snow layer started to really want to slide on the crust. Once I was in the meadows between Baldy and the M, at about 1400, I started hearing/feeling really wet "whumps". Photo: J. Harrison
Overnight temps 40 F at 8,000-9,500'. 50-60 F at 6,000-7,500'.
