Saw debris and what looked like a crown line from a natural avalanche that probably happened a day or two ago in palace butte basin on a NE aspect above Arden lake. My best guess is 150ft wide crown, 1-2ft deep?
About 34 degree rollover, 14 inch crown.
We measured 14" of snow from Tuesday's storm with 1.6" of snow water equivalent. We were encouraged that we did not see any natural (or human-triggered) avalanche activity. However, there is a significant caveat to this. East to Northeast winds stripped the steep slopes of Carrot and Sage Basins that are regularly wind-loaded by the prevailing winds. Thick drifts in abnormal locations were evident. Ridgetop were we rode had pillows of drifted snow and we could see cornices running downhill on the SW side of Sage Peak that indicated the gullies and depressions were cross-loaded. We dug a couple of pits. The first, in Sage Basin was unremarkable. The second, at the edge of Sunlight Basin, yielded an ECTP23 on a layer of facets/ surface hoar buried two feet deep.
We avoided wind-loaded slopes and recommend digging to test weak layers in the upper three feet of the snowpack before riding/ skiing in steep terrain.
<p><span><span><span><span><span><span>Yesterday had great visibility and offered a chance to see avalanche activity from Tuesday’s storm. All avalanche activity was confined to new snow, and the volume of activity was low. Skiers saw a natural avalanche on the north face of Mount Blackmore (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/28158"><span><span><span><strong><span… and photo</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>) and riders found a small slide on Buck Ridge (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/23/storm-slab-buck"><span><span><spa…;). Also, a snowmobiler triggered a small slide at Lionhead in Airplane Bowl (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/23/snowmobiler-triggered-avalanche-l…;). Dave and his partner rode in Taylor Fork where the new snow measured 14+” and he titled his field video, </span></span></span></span></span></span><a href="https://youtu.be/DukDqOrDgHA"><span><span><span><strong><em><u><span><s… Didn’t See Avalanches</span></span></u></em></strong></span></span></span></a><span><span><span><span><span><span>. Ian and his partner skied north of Bridger Bowl to the Ramp and found wind-affected snow, but no activity or hair-trigger avalanche conditions (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/28150"><span><span><span><strong><span… and video</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>This past storm dropped 12-18” of snow in the Madison and Gallatin Ranges (5-9” elsewhere) which measured up to 1.6” of snow water equivalent, a large load. Wind during the storm switched to the east and ridgelines that would normally be drifted were scoured. Conversely, slopes that are normally stripped of snow are now loaded. Keep in mind these unusual loading patterns as you travel. Although the Bridger Range is windy this morning, it is predicted to lessen quickly which will keep drifting to a minimum. We also have weak layers of faceted snow buried in the top 3 feet of the snowpack that are not immune to avalanching. Although the likelihood of triggering slides is decreasing, there’s still potential for releasing an occasional avalanche. As the danger decreases the snowpack’s instability becomes hidden. This requires us to search, dig and test. Shooting cracks in a wind drift or a poor stability test score will turn us around. </span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>For today, throughout our forecast area, the danger is rated MODERATE on all slopes. </span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Please share avalanche, snowpack or weather observations via our</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/add/snow_obs"><span><span><span><span>…; </span></span></span></span></span></span><span><span><span><strong><span><u><span><span>website</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, email (</span></span></span></span></span></span><span><span><span><strong><span><span>mtavalanche@gmail.com</span></span></strong></span></span></span><span><span><span><span><span><span>), phone (406-587-6984), or Instagram (#gnfacobs). </span></span></span></span></span></span><span><span><span><span><span><span> </span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Tuesday’s storm dropped well over a foot of new snow. Wind is blowing and drifts will grow thicker (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=VU_A-fTPYmw"><span><span><span><strong>… Park video</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). Buried weak layers in the upper three feet of the snowpack could result in avalanches breaking deep and wide. As the danger decreases the snowpack’s instability becomes hidden. This requires us to search, dig and test.</span></span></span></span></span></span></p>
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Airplane Bowl.
Small storm slab released on a small piece of terrain. East aspect around 9200.
Small storm slab released on a small piece of terrain. East aspect around 9200.
