Bad quality but a D2, R3 natural in Flanders cirque. Looked like it was just the new snow, but hard to say.... on a NW aspect around 9,500 feet. Photo: O. Desroches
From Big Sky Ski Patrol 1/21/23: "skier triggered a surface wind slab in Wyoming Bowl that broke 8-12” deep. It propagated to an estimated 150’ wide- SS, R1/D1.5... The slide was small, no one was hurt, and the avalanche was reported (which we appreciate), with no further public involvement other than the trigger."
Went on a "loop de doop" type of tour yesterday to see conditions around Big Sky. While skiing a north aspect off Middle Peak, we dug a pit around 10k and found a hard 6 inch wind slab on the sitting on top of a firm column, ECTP16 on this top layer and it seemed like this was an isolated problem. We skied a SW aspect from the Bear/Hellroaring ridge and found great, consolidated snow from ridge to creek. We ascended and dug a pit on a NE aspect in Bear basin and found the depth hoar that everyones been talking about, we found this about 2 feet deep and had collapse but no propagation in our stability test. We skied a SW aspect back into Middle Basin in solar affected snow, a few ski cuts cleaned out the chute and the snow ran slow, but capable of taking someone off their feet. Multiple point and release wet snow activities were observed on all similar aspects off of the ridge.
January 21, 2023 - January 21, 2023
January 21, 2023
RRS - Kevin Allred
Island Park
Yale Creek (SSW)
None Observed
None Experienced
None Experienced
Found a layer of near surface facets 25 cm from the surface not problematic now but with new snow coming this could become a layer of concern
Good
Moderate
Steady
The snow seems to be very stable found a MF crust 45cm / surface from a warming trend early in January. Below the MF layer a strong cohesive slab. 15cm layer of DH at ground level average grain size of 2 mm
Clear
17º
Calm , SW
Trace of new snow past 24 hours
Mostly clear skies light winds out of the south west no blowing snow
Avalanche Observation Comments:
None Observed
Head of Yale Creek 8470' elevation SSW aspect HS 175 CTM SC @ 20 cm below surface on a near surface FC. ECTN
Our primary concern is a layer of SH that is variable in distribution . This layer was not evident in our snow pit location.
Our travel plan avoid avalanche terrain over 30° We traveled to observe an avalanche fatality site from 1998. The area had heavily trafficked by snowmobile activity. We remained with our conservative travel plan at 30°
<p><span><span><span><span><span><span>In the mountains around Big Sky, West Yellowstone and Cooke City a weak layer of surface hoar buried 1-2 feet deep makes it possible for a person to trigger avalanches. Yesterday, moderate wind blew recent snow into fresh slabs that can avalanche under the weight of a person and could cause an avalanche to break deeper on buried surface hoar. Over the last week natural and human triggered avalanches broke on the surface hoar (</span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/27717"><span><span><span><strong><span… top details and photo</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/27740"><span><span><span><strong><span… details and photos</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/images/23/natural-avalanche-muddy-creek-hea… Ridge photo</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, </span></span></span></span></span></span><a href="https://www.mtavalanche.com/node/27682"><span><span><span><strong><span… City photo</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). This layer can be tricky to assess because it is not on every slope, and it isn’t breaking in every stability test (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=jmXIADy8rl0&list=PLXu5151nmAvTi1DBS… City video</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>, </span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=ibAh34muOQc&list=PLXu5151nmAvTi1DBS… video</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). It will become less likely to find an unstable slope as time passes without additional snowfall, but surface hoar can remain unstable for a long time and is notorious for surprises. Before riding in steep terrain, look for and avoid fresh drifts, and dig to look for and assess buried weak layers. Or, keep things simple and avoid steep slopes entirely (</span></span></span></span></span></span><a href="https://youtu.be/TV7IXE41Skg"><span><span><span><strong><span><u><span>… Lake video</span></span></u></span></strong></span></span></span></a><span><span><span><span><span><span>). Avalanches breaking on weak layers near the ground are unlikely, but a person might be able to trigger a slide from a shallower area in the snowpack where these layers are easier to affect. Today avalanches are possible to trigger and danger is MODERATE.</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>Over the last week, the Bridger Range and Hyalite received 5-7” of snow which was drifted into shallow wind slabs by moderate to strong west-northwest wind. Triggering these wind slabs has become less likely without additional new snow the last couple days, but a few wind-loaded slopes could remain unstable. Yesterday Ian and I looked at the snowpack on Saddle Peak and found weak snow buried 6-8” deep below a hard wind slab (</span></span></span></span></span></span><a href="https://www.youtube.com/watch?v=1VdaJ49vISg&list=PLXu5151nmAvTi1DBS…;). This indicates some drifts might remain unstable for longer than usual. Steer clear of round deposits of snow, especially where being caught in an avalanche would have high consequences like in steep terrain, above cliffs, rocks or trees.</span></span></span></span></span></span></p>
<p><span><span><span><span><span><span>We have not seen avalanches breaking on weak layers near the ground in the mountains around Bozeman, but plenty of weak snow exists. Before fully committing to ski or ride steep slopes, dig down to look for and assess potential weak layers. Today the avalanche danger is MODERATE on wind-loaded slopes. Otherwise the snowpack is generally stable and danger is LOW on non-wind loaded 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></p>
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Bad quality but a D2, R3 natural in Flanders cirque. Looked like it was just the new snow, but hard to say.... on a NW aspect around 9,500 feet
My ski partner and I dug a pit at the base of Divide peak on a SE facing slope at 9,600 ft. We had no failure in our compression test and an ECTX on our column test. The snowpack looked to be completely faceted yet consolidated from the ground to a crust layer just below the new soft snow. There was little evidence of wind loading in the basin and a layer of surface hoar was present on the snow surface. We passed another party who were digging multiple pits on a similar aspect and had the same results we found. We ran into a third party on the summit who dug a pit a few hundred feet from the summit that showed a slightly stiffer slab on the surface but again found stable results. This is still a tricky snowpack and this only shows that conditions were stable on this day at very specific locations. If you venture into Hyalite still do your homework before dropping in!
Visible transport on with wind direction shifting from SW to NW in the afternoon. Dug at 7760' asp 85deg slope angle 20 deg on the South side of Bradley's. HS 180 ECTP10 down 25cm. 1F+ hard wind slab over F hardness snow. Slab was not consistent on that aspect at that elevation, we definitely hunted for potential reactivity with many handpits during an avalanche course.
