21-22

<p>Strong winds combined with a few inches of new snow have created thin fresh drifts that could break in small avalanches today. These will be the most obvious avalanche hazard today, but not the most worrisome. The less likely but more dangerous possibility is triggering an avalanche on the weak layers buried deeper in the snowpack. These avalanches could break 3-5 ft deep. A slide on Mount Abundance a few days ago (<a href="https://www.mtavalanche.com/images/22/large-natural-mt-abundance-1"><st…;, <a href="https://www.mtavalanche.com/images/22/large-natural-mt-abundance-2"><st…;) and the fatal avalanche last week on Scotch Bonnet (<a href="https://www.mtavalanche.com/accident/21/12/30"><strong><u>details</u></…;) provide sobering examples of the sort of slides that could break today. The possibility of triggering one of these slides keeps us hesitant to ride slopes steeper than 30 degrees. The avalanche danger is MODERATE today.</p>

<p>In the Bridger Range thin wind slabs could break beneath freshly drifted snow or avalanches could break deeper on a thin layer of weak, faceted snow buried 1-3 ft deep. The weak layer that has been acting up in the Bridger Range is in the middle or upper snowpack instead of near the ground. Last week’s slides on Saddle Peak show why we’re concerned about avalanches breaking on this weak layer (<a href="https://www.mtavalanche.com/node/25329"><strong><u>details</u></strong>…;, <a href="https://www.mtavalanche.com/images/22/natural-large-wind-slab-argentina…;, <a href="https://www.mtavalanche.com/images/22/natural-avalanche-saddle-peak"><s…;). This weak layer appears to be widely distributed so assume it is on every slope and plan your route according. Human triggered avalanches are possible and the avalanche danger is MODERATE.</p>

<p>Large avalanches are unlikely in the Northern Madison and Northern Gallatin Ranges. A few inches of new snow and strong winds have built thin wind slabs, but these will generally be thin enough and/or well bonded enough to not be a significant hazard. Stay on alert in case you find a slope with a thicker slab of wind drifted snow that is not well bonded. Cracks shooting out in front of your skis or snowmobile mean that you’ve found a problematic drift. Yesterday on Mt. Ellis I was finding the same generally stable snowpack we’ve seen elsewhere in the northern ranges, but I still dug a snowpit just before entering avalanche terrain as a double check to make sure I didn’t get surprised (<a href="https://www.youtube.com/watch?v=Zp4MIwaLaac"><strong><u>video</u></stro…;). Search for signs of isolated instability and be ready to adjust your plans accordingly. The avalanche danger is LOW.</p>

<p>If you get out, please send us your observations no matter how brief. You can submit them via our <a href="https://www.mtavalanche.com/node/add/snow_observation"><strong><u>websi…;, email (<a href="mailto:mtavalanche@gmail.com"><strong><u>mtavalanche@gmail.com</u></str…;), phone (406-587-6984), or Instagram (#gnfacobs).</p>

<p>After a three-day break in snowfall, the southern ranges of our advisory area received 3” of snow equal to 0.3” of <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/null/?cid=nrcseprd1314… water equivalent</a> - SWE and strong winds are transporting it into unstable drifts. While small avalanches within the several inches of new snow will be the most likely indicator of instability, the real concern is buried deeper in the snowpack in the form of a weaker layer of snow crystals called facets. Avalanches could break 4-5’ deep on this weak layer like the slide on Mount Abundance several days ago (<a href="https://www.mtavalanche.com/images/22/large-natural-mt-abundance-1"><st…;, <a href="https://www.mtavalanche.com/images/22/large-natural-mt-abundance-2"><st…;) or 1-2’ deep within the recently drifted snow. With weak layers deep in the snowpack, we will be slower to trust steep terrain and, as the snow builds up today, keep a watchful eye out for signs of rising instability (<a href="https://www.youtube.com/watch?v=K4yEaUsqo6A"><strong>Lionhead video</strong></a>).</p>

<p>Be cautious around wind-loaded slopes and carefully evaluate the snowpack and the consequences of the terrain because human-triggered avalanches are possible. Today, the avalanche danger is MODERATE.</p>

<p>The Bridger Range received 4” of new snow equal to 0.3” of SWE. The combination of new snow, recent wind-loading, and a weak layer of faceted snow buried 1-3’ deep makes human-triggered avalanches possible today (<a href="https://mtavalanche.com/images/22/wind-loading-saddle-peak"><strong>win… photo</strong></a>, <a href="https://www.youtube.com/watch?v=Iv0tVbc9VZw&amp;list=PLXu5151nmAvT1nrM2… Peak video</strong></a>, <a href="https://www.youtube.com/watch?v=kXE-CWnV_NY"><strong>northern Bridger video</strong></a>). While the new snow will not dramatically change the danger, avalanches failing 1-3’ deep on Saddle Peak last week are indicators of the continued concern (<a href="https://www.mtavalanche.com/node/25329"><strong>details</strong></a&gt;, <a href="https://www.mtavalanche.com/images/22/natural-large-wind-slab-argentina…;, <a href="https://www.mtavalanche.com/images/22/natural-avalanche-saddle-peak"><s…;). Look for signs of instability such as cracking or collapsing and dig a snowpit to assess buried weak layers before considering recreation in avalanche terrain today. The avalanche danger is MODERATE.</p>

<p>The snowpack in the Northern Madison and Northern Gallatin Ranges is generally stable and the 1-4” of new snow (0.1-0.3” of SWE) will not significantly change the danger. Yesterday at Divide Peak, my partner and I found stable conditions. The day prior, a group just to the north of us found an isolated area of unstable snow in technical terrain and choose to return home rather than proceed (<a href="https://www.youtube.com/watch?v=brmqHcFKWV4"><strong>video</strong></a&…;). Follow safe travel protocols to limit your exposure, look for signs of isolated instability and carefully consider the consequences of smaller avalanches in terrain that amplify the danger. The avalanche danger is LOW in the Northern Madison and Northern Gallatin Ranges.</p>

<p>If you get out, please send us your observations no matter how brief. You can 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>