21-22

KNB avalanche, Republic Cr, Cooke City

Date
Activity
Skiing

I talked to Dave about this incident and gave him a detailed description and here are some photos.  Would appreciate not sharing the burial photos that include people publicly but hopefully the others help.  We were in rescue mode so documenting this wasn't a priority.  

I'd call it a D2.5, 3 ft crown,  250-300' wide and ran @ 400'+ vert.  

1 skier buried with arm out, one skier able to hug a tree on the side of one gully and another skier blown through small trees and sustained likely broken ribs.  6 total in party.  

 

 

Region
Cooke City
Location (from list)
Woody Ridge
Observer Name
Will Carlton

3 skiers caught, 2 injured on Woody Ridge near Cooke

Woody Ridge
Cooke City
Code
HS-ASu-R2-D2.5-O
Elevation
9500
Aspect
W
Latitude
44.99330
Longitude
-109.92500
Notes

On March 24, 2022 a group of six skiers descended the west side of Woody Ridge near an area locally
known as KNB's. Approximately a third of the way down the slope the group triggered an avalanche that
crossed three gullies, broke 1-3 feet deep, 275 feet wide (measured on GoogleEarth) and ran 700 feet
vertical. Five skiers were stopped, watching one descend the slope. Three of the stopped skiers were in a
row of dense trees directly above and adjacent to where the slide broke and two were stopped a few
feet below the trees. The avalanche caught the skier and two members of the group who were stopped
downhill of the trees. One skier was pinned against a tree and the avalanche passed him. The second
skier slid into a tree sustaining multiple suspected rib fractures. The third, who was actively skiing, was
caught, carried and partially buried with just his arm sticking out of the snow, 500 vertical feet below the
avalanche crown. All three captured skiers successfully deployed their airbags.

The three remaining members of the group switched their avalanche transceivers to search and located
all three victims, and unburied the partially buried skier within five minutes. All members of the group
had formal avalanche training: Avalanche Level 1 and 2 up to a Pro Level 2. All members of the group had
avalanche transceivers, shovels, probes and airbags. The group performed field first aid and
self-evacuated to Cooke City.

CLICK HERE FOR FULL REPORT

Number of slides
1
Number caught
3
Number buried
0
Avalanche Type
Hard slab avalanche
Trigger
Skier
Trigger Modifier
u-An unintentional release
R size
2
D size
2.5
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness
24.0 inches
Vertical Fall
700ft
Slab Width
275.00ft
Weak Layer Grain type
Faceted Crystals
Weak Layer grain size
2.00mm
Weak Layer Hardness
F
Slab Layer Grain Type
Decomposing and Fragmented precipitation particles
Slab Layer Hardness
1F
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

GNFAC Avalanche Forecast for Thu Mar 24, 2022

Snowpack and Avalanche Discussion

<p>We are most concerned about wet avalanches today. The forecasted sunny skies is bad news. Small changes in today’s weather will have oversized consequences. Sunshine on slopes will quickly melt the surface crust that froze last night. Without wind blowing across the snow surface, melting will accelerate. Conversely, even a small breeze could help cool the snow. Temperatures are forecasted to be a few degrees cooler which might delay wet activity but not stop it. We are ripe for wet avalanches because the snow surface did not freeze thick and wet snow still exists under last night’s crust. Ian and Dave skied into Mt. Wheeler in the northern Gallatin Range yesterday and found wet snow that was unsupportable when they stepped out of their skies (<a href="https://youtu.be/g0T8RQK3oN0"><strong><u>video</u></strong></a&gt;). Skiers in Hyalite saw a cornice break free because of warming and also saw many loose wet avalanches and one wet slab avalanche (<a href="https://www.mtavalanche.com/node/26318"><strong><u>details</u></strong>…;). I expect more of the same today from the Bridger Range to West Yellowstone. It’s time to turn around if you are sinking past your boot tops in wet snow or see wet-loose avalanches.</p>

<p>There are still plenty of slopes with dry snow on northerly facing high elevation slopes, but you’ll have to pass through low elevation wet snow to get there and return. It can still feel like winter up high and although we are most worried about wet avalanches, dry snow harbors a weakness a foot or two under the surface. In the last three days we found this layer of weak faceted snow on Mt Wheeler, Taylor Fork (<a href="https://youtu.be/xfsTNFGizC8"><strong><u>video</u></strong></a&gt;) and above Hebgen Lake (<a href="https://youtu.be/qpHmopLM8j0"><strong><u>video</u></strong></a&gt;). In dry snow we must dig to assess the stability.&nbsp;</p>

<p>Both wet and dry avalanches are possible today and the danger is rated MODERATE. <em>However, if we get a trifecta of sunshine, no wind and mountain temperatures in the 40s, the wet snow avalanche danger would climb to CONSIDERABLE since widespread wet-loose and a few wet slab avalanches will occur. </em></p>

<p>Today, the mountains around Cooke City are not getting as warm or seeing as much sun as the other ranges. Clouds and a breeze will keep the snow surface from getting warm enough to avalanche. In dry snow there is a weak layer of sugary facets a foot or two under the surface. Skiers got two large collapses on this layer in Yellowstone National Park on Barronette Peak which is outside our forecast area (<a href="https://www.mtavalanche.com/node/26317"><strong><u>details</u></strong>…;). It was in a thin, 4 foot deep snowpack, but worth noting since similar conditions could be found in thinner snowpacks around Cooke City. For today, both wet and dry avalanches are unlikely and the danger is rated LOW.&nbsp;</p>

<p>If you get out, please send us your observations no matter how brief. You can submit them via our website, email (mtavalanche@gmail.com), phone (406-587-6984), or Instagram (#gnfacobs).</p>

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Cornice collapse, many wet slides in Hyalite

Maid of the Mist
Northern Gallatin
Code
WL
Latitude
45.41640
Longitude
-110.97000
Notes

Solar input triggered small cornice collapse while booting up fat maid that ran by our group, but did not trigger anything from its impact on the slope. We saw many wet avalanches both small and large, mostly loose, but one slab that came down the south east face of Bole after skiing the pinner. 

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Wet loose-snow avalanche
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

Large collapses on Barronette Peak

Barronette Peak
Cooke City
Code
Latitude
44.97520
Longitude
-110.08700
Notes

While ascending the SSW ridge of Baronette - via Pebble Creek trailhead - we had 2 major collapses around 8,800' in low angle terrain. The largest collapse was roughly 50'x100' with visible cracks on the perimeter. HS on both slopes was ~120cm. S aspect. The weak layer was failing about 30cms down in facets. 

Surface of the snowpack was a 2" thick melt freeze crust that supported body weight with skis on. 

boot pen. - Basically the whole snowpack. 

Number of slides
0
Number caught
0
Number buried
0
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Red Flag
Advisory Year

Warming

Date
Activity
Skiing

Solar input triggered small cornice collapse while booting up fat maid that ran by our group, but did not trigger anything from its impact on the slope. We saw many wet avalanches both small and large, mostly loose, but one slab that came down the south east face of Bole after skiing the pinner. Due to this information we chose not to ascend the south facing gully that follows the ridge north of Bole and ski the north couloir into Alex Lowe basin. On the north aspects we found punchy, difficult, wind affected snow from the most recent storm. It was cold, dry snow, completely un-reactive in our tests, but hooky challenging skiing. 

Region
Northern Gallatin
Location (from list)
Maid of the Mist
Observer Name
Jacko