We intentionally triggered this 6-8" deep wind slab on Saddle Peak on December 23, 2021, E aspect at 9,000'. It showed us that recently formed wind slabs were still reactive. This hard slab formed over low density new snow which made it unstable. While not large, these slides will easily push you down and can be harmful if they push you into hazardous obstacles or terrain traps. Photo: GNFAC
21-22
On December 23, 2021 we went out to Saddle Peak and dug three snowpits. We found a 2-3 foot deep, generally stable snowpack with a lack of unstable buried weak layers. Photo: GNFAC
GNFAC Avalanche Forecast for Thu Dec 23, 2021
Snowpack and Avalanche Discussion
<p>The spigot is turned on for Cooke City. Seven inches of snow (.7” <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/null/?cid=nrcseprd1314… water equivalent</u></a>) and more forecasted with strong west wind will raise the avalanche danger. Today will be stormy and avalanches are likely to be triggered on slopes that are wind-loaded. <em> </em>A natural avalanche on Sheep Mountain on Tuesday illustrates this instability (<a href="https://www.mtavalanche.com/images/21/natural-avalanche-sheep-mountain"…;). <a href="https://youtu.be/QOBIciPigDY"><strong><u>Dave’s video from Monday</u></strong></a> outlines his concern with wind-drifted snow. On some slopes the snowpack has a weak layer of faceted, sugary snow in it’s lower third which will become more sensitive to avalanching as the snow piles up. For today, be mindful of the increased likelihood of triggering slides which must be balanced with our stoke of new snow. The avalanche danger is rising and rated CONSIDERABLE on wind-loaded slopes and MODERATE elsewhere.</p>
<p>Ian and I rode into Tepee Basin in the southern Madison Range yesterday and saw many small avalanches that slid last week during the High danger. These failed on sugary, faceted snow near the ground (<a href="https://www.mtavalanche.com/images/21/teepee-basin-avalanche-1-0"><stro…;, <a href="https://www.mtavalanche.com/images/21/tepee-basin-avalanche-2"><strong>…;). We dug in the flanks of an avalanche and confirmed the poor structure (<a href="https://youtu.be/2rjpm0iLm_I"><strong><u>video</u></strong></a>, <a href="https://www.mtavalanche.com/images/21/tepee-basin-profile-22-dec-2021">… profile</u></strong></a>) which resembled the snowpack at Lionhead (<a href="https://youtu.be/7EEn6f8-4fA"><strong><u>video</u></strong></a>). This area got 1-2” of new snow yesterday which will not adversely affect the stability. However, it remains possible to trigger avalanches on steep slopes that either have a wind-drift or weak facets underlying the snowpack. For today the avalanche danger is rated MODERATE on all slopes.</p>
<p>From the Bridger Range to Big Sky the snowpack is 2-3 feet deep and harbors a layer of faceted snow near the ground that is not very reactive. In the last 48 hours we have been to Buck Ridge (<a href="https://youtu.be/cf-qqv2Ssjw"><strong><u>video</u></strong></a>), Beehive Basin (<a href="https://youtu.be/ePMCJs3qAs0"><strong><u>video</u></strong></a>) and Mt. Blackmore (<a href="https://www.mtavalanche.com/images/21/snowpack-wind-loaded-slope-mt-bla…;, <a href="https://www.mtavalanche.com/images/21/scoured-thin-snowpack-n-face-mt-b…;). The story is the same in each: in areas where previous wind-loading created stiff, dense drifts, we can occasionally get them to break on this faceted (sugary) layer in our stability tests. For today, it is possible to trigger a small slide on these isolated drifts which are found on many aspects and elevations. The avalanche danger is rated MODERATE on slopes with older wind drifts and LOW on all others.</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>
Upcoming Education Opportunities:
Get your avalanche brain ready for the season at one of the many classes listed on our education calendar, and list of upcoming events below.
Every Saturday near Cooke City, 10 a.m.-3 p.m. FREE snowpack update and transceiver/rescue training. Stop by for 20 minutes or more at the Round Lake Warming Hut.
Friends of GNFAC Powder Blast Fundraiser
Pit from 12/22/21 at 9,850' on the NE face/shoulder of Mt. Blackmore. Snow depth was 111cm, first ECT was ECTN10 below the wind slab then ECTN22 on facets at 70cm. A second test was ECTN17 on that facet layer, then ECTP20 on depth hoar at 35cm. A third ECT was ECTP17 on the facets at 70cm, then a fourth ECT was another ECTP17....
North face of Mt. Blackmore on 12/22/21. South-southwest winds were moderate-strong and scouring more than loading it seemed like, but isolated slabs and whales of snow could be found. We did not get any drifts to crack or collapse. Fresh wind slabs were 2-4" thick, 1f-P hard, and not very continuous. Photo: GNFAC