21-22

<p>Moderate winds out of the northwest to west will form fresh drifts of snow that can avalanche under the weight of a person. Snowfall on Thursday night dropped up to 9” of snow near Bozeman (0.8-1.3” <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/null/?cid=nrcseprd1314… Water Equivalent</a>) and 5-8” in the Madison Range (0.5<strong>-</strong>0.6” SWE). Near Cooke City got 6-8” since Tuesday (0.6” SWE).</p>

<p>Winds have been calm to light leaving the recent snow to be transported by today’s wind, except in the Bridger Range where moderate winds yesterday formed drifts which were easy to trigger with skis and snowmobiles (<strong><a href="https://www.mtavalanche.com/images/22/snowmobile-triggered-wind-slab-sm… of snowmobile triggered wind slab</a></strong>). Yesterday Ian and I went to Taylor Fork where wind was calm (<strong><a href="https://www.youtube.com/watch?v=I6AleixLxTI&amp;list=PLXu5151nmAvT1nrM2…;). We did not see signs of instability, but there was 8” of low-density snow that will be drifted into unstable slabs today. Be cautious of wind-loaded slopes, and avoid them if you see signs of unstable fresh drifts such as wind transporting snow across ridgelines, cracking across the snow surface or fresh avalanches.</p>

<p>Yesterday, a skier near Cooke City triggered a shallow, but wide avalanche in a steep couloir (<strong><a href="http://www.mtavalanche.com/node/25595">photo and details</a></strong>). A separate group of skiers near Cooke City dug down and had unstable test results break under the recent snow and chose a different objective. Layers of surface hoar or near surface facets were buried by the recent snow in the southern half of our advisory area which could make fresh drifts easier to trigger. If other signs of instability are not present, before riding steep slopes dig and do a quick stability test to look for unstable weak layers buried below the recent snow (<strong><a href="https://www.mtavalanche.com/images/22/surface-hoar-layer-s-madison-rang… of buried surface hoar</a></strong>). In addition, although unlikely, a much larger avalanche breaking on weak snow near the bottom of the snowpack could be triggered by a smaller avalanche or cornice fall.</p>

<p>Avalanches are possible today and danger is MODERATE on wind-loaded slopes. On non-wind loaded slopes avalanche danger is LOW.</p>

<p>The recent storm dropped 3-4” (0.4” SWE) near West Yellowstone. This is minimal weight added to a generally stable snowpack, and large avalanches are unlikely (<strong><a href="https://www.youtube.com/watch?v=g7Pl9-raU7g">video from Lionhead</a></strong>). Drifts will form from moderate west-northwest winds today which will be generally small and isolated hazards. Watch out for fresh drifts along ridgelines and in very steep terrain, above cliffs, or slopes where getting knocked off your feet by a small avalanche would have high consequences. Overall, large avalanches are unlikely and 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>website<…;, email (<a href="mailto:mtavalanche@gmail.com"><strong>mtavalanche@gmail.com</strong></a…;), phone (406-587-6984), or Instagram (#gnfacobs).</p>