Skier riding down to the crown around 12:45 pm Christmas Day. Photo: M. Loge
20-21
Collapses near Cooke City
Several collapses and whumpfs reported by skiers in low elevation meadows in the Republic Creek area and around Mt. Fox.
GNFAC Avalanche Forecast for Fri Dec 25, 2020
<p>Weak, sugary snow at the ground has been struggling to accommodate the load of snow piled on top of it by the last storm. As new snow fell and strong winds built a slab, there were both natural and human triggered avalanches (<a href="https://www.mtavalanche.com/images/20/natural-avalanche-divide-cirque">…;, <a href="https://www.mtavalanche.com/node/23324"><strong><u>details</u></strong>…;, <a href="https://www.mtavalanche.com/avalanche-activity"><strong><u>avalanche activity list</u></strong></a>). As we get further out from the loading event, the snowpack is getting less touchy, but triggering a slide is still possible on any slope where a cohesive slab developed (<a href="https://youtu.be/IUb9ub26y1o"><strong><u>video</u></strong></a>). The snowpack structure remains poor. We don’t trust it and neither should you. Unfortunately, the weak layers near the ground won’t heal quickly. Natural avalanches seen yesterday on Bridger Peak are a good example of the sort of slide you could trigger today (<a href="https://www.mtavalanche.com/images/20/natural-avalanches-bridger-peak">…;). </p>
<p>Watch for signs of instability - recent avalanches, collapses, or cracks shooting out in front of you. If you see any of these signs, reevaluate plans to get into avalanche terrain. If you don’t see any obvious signs, dig down to keep searching for instability in the snowpack before committing to steep slopes (<a href="https://www.youtube.com/watch?v=Gk8W8nlUMpw"><strong><u>video</u></stro…;). As triggering avalanches remains possible, the avalanche danger is MODERATE today.</p>
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<p>Our primary concern around Cooke City is avalanches breaking under the new snow on wind-loaded slopes. While Cooke City got the most snow out of this last storm (over 2 ft of snow measuring 2.2” <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/or/snow/?cid=nrcs142p2… water equivalent</u></a>), it fell on a snowpack without widespread weak layers. During the storm earlier in the week, many natural avalanches broke on steep, rocky, wind-loaded slopes (<a href="https://youtu.be/bHZazXX4EXM"><strong><u>video</u></strong></a>, <a href="https://youtu.be/Ava7FSUx9kY"><strong><u>video</u></strong></a>). It is getting harder to trigger one of these slides, but remains possible. Stay safe by steering around the steepest, rockiest, most windloaded areas near ridgelines. The avalanche danger is MODERATE today.</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>
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Upcoming Avalanche Education and Events
See our education calendar for an up to date list of all local classes. Here are a few select upcoming events and opportunities to check out:
Natural avalanches on Bridger Pk
Observed multiple natural avalanches on Bridger Peak around 1200 on 12/24/20. Broke within last 24 hours. These appeared to be the recent storm snow breaking on weak ddepth hoar 1-3 feet deep. Showing good ppropagation and entraining weak snow in the ttrack Storm on 12/22-12/23 totaled 8-12" (.3-.5" SWE).
Natural avalanches on Bridger Peak observed at 1200 on 12/24/20. These occurred within the last 24 hours after the area had 8-12" of snow (.3-.5" SWE) and strong winds. Weak sugary snow on the ground failed under the weight of fresh slabs. This activity is a sign that the snowpack has a poor structure that will struggle to support future storms. Photo: GNFAC
This recent avalanche activity was observed at 1200 on 12/24/20, and occurred in the last 24 hours. Photo: GNFAC
Forecast link: GNFAC Avalanche Forecast for Fri Dec 25, 2020