Lots of avalanche activity. Lots of cracking and propagation from the skis.
Today our party of three skied Blackmore peak, knowing beforehand the new snow and wind would keep us off the standard East Ridge to the summit, but still wanted to ski a lap on the lower section of that same ridge. Beforehand we were able to easily trigger shallow, short running windslabs by knocking down small cornices. We then headed up to the summit from the largely low angled SE sub-ridge and skied wind scour back to the trail. This lower angle terrain whumped on us a few times, whenever we stepped out of the trees, a hasty hand pit showed a thin sun crust under the new snow interface to be the culprit. Thought the attached picture may help some folks decided on weekend plans. Thanks!
Pretty solid conditions yesterday. Some drifting occurring at the top but better then expected. Pit showed a right side up pack with the usual small layer of facets at ground level. ICT 25, slight but stable wind packed layer on top 2 in. Decent felt really good and conditions felt comfortable enough to ski any aspect on Ellis.
<p><span><span><span><span><span><span>Two feet of new snow and winds gusting up to 75 mph have created very dangerous avalanche conditions. Avoid traveling on or beneath any steep slopes. If you get onto a steep slope you </span></span></span></span></span></span><span><span><span><strong><span><span>will</span></span></strong></span></span></span><span><span><span><span><span><span> trigger an avalanche or one could break all by itself above you. Avalanches may break within the storm snow or deeper and wider on weak layers that have been severely overloaded (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=PVQkjFvFnnw&feature=emb_logo"><span…;). Drifting snow will continue today, adding additional load to windloaded slopes. The avalanche danger is HIGH on all slopes.</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Over the past 48 hours, over two feet of new snow fell around Cooke City with strong winds (see </span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=_pW53Czv9vs"><span><span><span><strong>…’s video from yesterday</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). Human triggered avalanches are likely on all slopes, especially wind loaded ones. Snowfall stopped this morning and we just barely avoided an avalanche warning. The avalanche hazard is very serious today and cautious route finding is essential for safe travel. The avalanche danger is CONSIDERABLE.</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>A foot of new snow fell onto a weak snowpack over the last two days. A widespread weak layer beneath the new snow will make avalanches break easily. The avalanche danger is CONSIDERABLE.</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>5-8” of light density snow fell overnight. Watch out for areas where the new snow has drifted into deeper cohesive slabs. It’s still early season so we don’t have too much confidence in the lower snowpack yet - dig before getting into avalanche terrain to make sure there isn’t a buried weak layer hiding down there. For today, the avalanche danger is rated MODERATE.</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>If you get out, 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></p>
<p><span><span><span><span><span><span>Two feet of new snow and very strong winds have created very dangerous avalanche conditions. Decision making is easy today - simply avoid traveling on or beneath any steep slopes. If you get onto a steep slope you </span></span></span></span></span></span><span><span><span><strong><span><span>will</span></span></strong></span></span></span><span><span><span><span><span><span> trigger an avalanche or one could break all by itself above you. Avalanches may break within the storm snow or deeper and wider on weak layers that have been severely overloaded </span></span></span></span></span></span></p>
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AVALANCHE WARNING for Lionhead and Island Park
Winds shifted to N-W and decreased dramatically overnight
We rode near Cooke City where more than 20" of snow has fallen since yesterday morning, and more snow is expected tonight. This new snow creates dangerous avalanche conditions and we expect natural and human-triggered avalanches over the next 24-72 hours. While touring on skis we experienced a couple large collapses.
At our snowpit, HS was 55-60” (140-150cm), New snow was 21”=1.2”SWE, and we had ECTP19 and 23 above a melt-freeze crust that formed last week, buried 26-28” deep (6-8” below the newest snow). The snowpack below the crust was small rounded facets (0.5-1mm) and average 4F to 1F hard. Snowfall was 1-2cm/hr. Wind was gusting moderate to strong and seemed like it was hitting harder above us, at ridgelines and starting zones.
On Dec 1, 2022 we found 21" new snow = 1.2"SWE that fell since the morning of 11/30. We had an ECT break and propagate 6-8" below the new snow on top of a crust that formed last week. With more snow on the way we might see avalanches break on this layer. Photo: GNFAC
ECT Results - ECTN 11 at 55cm
Location: Bacon Rind, Skillet, about the center of the upper skillet meadow, approx 100' below the ridge line N 44deg58.3210' W 111deg05.8191
Weather: Temp ~25F, cloudy, moderate snowfall, winds mild in trees, moderate winds on ridge line
Heading: E (110deg)
Elevation: 8890
Slope Angle: 34deg
Total Snow Depth: 110cm
We observed about 50-55cm of new and wind deposited snow on the eastern aspects that we assumed had been from snowfall/wind over the last week. This new snow layer was generally F hardness. The new snow was weakly supported by a 3cm thick faceted layer. The ECTN 11 result was due to this faceted layer collapsing. The remaining base snow pack was 50-55cm thick and approximately 2F hardness. We repeated the test 2x in the same pit by digging back and retesting, the faceted layer failed both times without propagation, the ECTN 11 result was clear in the second test, the first test was hard to interpret but allowed us to identify the problem layer. ECTX result on the remaining 55cm thick base snow layer.
Wind loading produced dense snow drifts that were prevalent along the ridge line, but in the protected east aspect meadows below the ridge line there was much less evidence of denser wind loading. We did not observe any whoomping either skinning up or skiing down or any signs of natural avalanches. We skied the east facing short meadow just south of the skillet, then skied the SW facing meadow to the west of the ridge line and lastly skied the skillet to the valley floor. As someone else reported earlier in the season the bottom half elevation of the run to the valley floor has many exposed downed trees and hidden hazards, personally I won't return to ski there until there is more snow depth at lower elevations. The SW facing meadow had a supportable suncrust layer, with a mix of 6"-24" of wind drifted new snow depth, depending on where/how the wind had scoured it.
