21-22

GNFAC Avalanche Forecast for Wed Mar 2, 2022

Snowpack and Avalanche Discussion

<p>As we noted in Beehive Basin yesterday, a mixed bag of weather including strong winds, light snow, light rain and warm temperatures, brings a mixed bag of avalanche problems to the mountains around Bozeman, Big Sky and West Yellowstone (<a href="https://www.youtube.com/watch?v=NpVCxX2idUs"><strong>video</strong></a&…;). Keep your senses keen for changing conditions and signs of instability associated with wind-loading, wet snow and persistent weak layers.</p>

<ol start="1" type="1">
<li>Recently winds loaded slopes with large drifts&nbsp;could avalanche. In the Bridger and Northern Gallatin Ranges this weekend, skiers and riders triggered avalanches breaking up to several hundred feet wide and 18” deep, small slides and shooting cracks (<a href="https://www.mtavalanche.com/avalanche-activity"><strong>avalanche activity list</strong></a>). On Monday, Doug and his partner got brutalized by the wind to make a <a href="https://www.youtube.com/watch?v=Yaw6TM1HXIE"><strong>video</strong></a&…; telling us that wind-loading is a problem. Listen to his advice and avoid wind-loaded slopes.</li>
<li>Wet snow avalanches are a concern where the snowpack did not freeze last night and there was light rain yesterday (primarily the Bozeman and Big Sky areas). The snow will continue to weaken and wet snow avalanches will become more widespread with continued warm temperatures. Recognize increasing danger if you are sinking into unsupportable wet or slushy snow.</li>
<li>A weak layer of facets buried 6-18” deep will exacerbate the above issues. This layer could result in localized instability on its own, especially where there is more new snow. Dig and test the snowpack for these layers.</li>
</ol>

<p>Plenty of safe skiing and riding exists. However, stay heads up for changing conditions, signs of instability and utilize safe travel practices. The danger is MODERATE.&nbsp;</p>

<p>The mountains around Cooke City received 5” of new snow equal to 0.5” of <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/detail/null/?cid=nrcseprd1314… water equivalent</a> in the last 48 hours and moderate winds are transporting snow onto slopes with weak layers buried around 2’ deep. Yesterday, a group of skiers near Goose Creek triggered an avalanche that broke 60’ wide and 12-16” deep on these weak layers. The skier lost a ski in the debris but was otherwise unharmed (<a href="https://www.mtavalanche.com/node/26049"><strong>photos and details</strong></a>). Riders and skiers triggered five other avalanches that we know of last weekend and Alex triggered a “whumph” on Sunday, indicating unstable snow (<a href="https://www.mtavalanche.com/avalanche-activity"><strong>avalanche activity list</strong></a>, <a href="https://www.youtube.com/watch?v=SxPaEcKATts&amp;list=PLXu5151nmAvT1nrM2…;). Larger avalanches like that on Mount Abundance last week are less likely but remain possible (<a href="https://www.youtube.com/watch?v=LHkbEAf1rlM&amp;list=PLXu5151nmAvT1nrM2…;

<p>Today, if you observe signs of instability, get unstable test scores or see a poor snowpack structure, make more conservative terrain choices. Human-triggered avalanches are possible and the danger is MODERATE.</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>website<…;, email (<a href="mailto:mtavalanche@gmail.com"><strong>mtavalanche@gmail.com</strong></a…;), phone (406-587-6984), or Instagram (#gnfacobs).</p>

Upcoming Education Opportunities

See our education calendar for an up-to-date list of all local classes. Here are a few select upcoming events.

March 4, Companion Rescue Clinic with the Bozeman Splitfest. Information and registration HERE.

Skier triggered Soft Slab Avalanche in Goose Creek

Goose Creek
Cooke City
Code
SS-ASu-R2-D1.5-O
Latitude
45.09230
Longitude
-109.95100
Notes

From Obs: "A group of six of us were sled-skiing in Goose Creek today and I triggered a soft-slab avalanche on a wind loaded slope. We had skied 3-4 runs in the trees before lunch and had seen little to no signs of instability. We'd come to this area three days earlier to dig pits and found the PWL noted in avalanche report for Cooke City. There was an older crown about ~5 days old clearly visible in the bowl we decided to ski after lunch. I dropped in and skied off a cliff just to lookers left of the crown "triangle" and when I landed I triggered the avalanche. It broke roughly 60 feet wide with a crown depth of 12-16". I was able to self arrest less than 20 seconds after the avalanche started and the snow slid around me. I lost a ski but was otherwise unharmed. I also had an airbag but did not need to pull it." 

Number of slides
1
Number caught
1
Number buried
0
Avalanche Type
Soft slab avalanche
Trigger
Skier
Trigger Modifier
u-An unintentional release
R size
2
D size
1.5
Bed Surface
O - Old snow
Problem Type
Persistent Weak Layer
Slab Thickness
16.0 inches
Slab Width
60.00ft
Weak Layer Grain type
Faceted Crystals
Slab Thickness units
inches
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

From Obs: "A group of six of us were sled-skiing in Goose Creek today and I triggered a soft-slab avalanche on a wind loaded slope. We had skied 3-4 runs in the trees before lunch and had seen little to no signs of instability. We'd come to this area three days earlier to dig pits and found the PWL noted in avalanche report for Cooke City. There was an older crown about ~5 days old clearly visible in the bowl we decided to ski after lunch. I dropped in and skied off a cliff just to lookers left of the crown "triangle" and when I landed I triggered the avalanche.

Cooke City, 2022-03-01

From Obs: "A group of six of us were sled-skiing in Goose Creek today and I triggered a soft-slab avalanche on a wind loaded slope. We had skied 3-4 runs in the trees before lunch and had seen little to no signs of instability. We'd come to this area three days earlier to dig pits and found the PWL noted in avalanche report for Cooke City. There was an older crown about ~5 days old clearly visible in the bowl we decided to ski after lunch. I dropped in and skied off a cliff just to lookers left of the crown "triangle" and when I landed I triggered the avalanche.

Cooke City, 2022-03-01

Soft Slab Avalanche in Goose Creek

Date
Activity
Skiing

A group of six of us were sled-skiing in Goose Creek today and I triggered a soft-slab avalanche on a wind loaded slope. We had skied 3-4 runs in the trees before lunch and had seen little to no signs of instability. We'd come to this area three days earlier to dig pits and found the PWL noted in avalanche report for Cooke City. There was an older crown about ~5 days old clearly visible in the bowl we decided to ski after lunch. I dropped in and skied off a cliff just to lookers left of the crown "triangle" and when I landed I triggered the avalanche. It broke roughly 60 feet wide with a crown depth of 12-16". I was able to self arrest less than 20 seconds after the avalanche started and the snow slid around me. I lost a ski but was otherwise unharmed. I also had an airbag but did not need to pull it.

Region
Cooke City
Location (from list)
Goose Creek
Observer Name
G. Shaw

GNFAC Avalanche Forecast for Tue Mar 1, 2022

Snowpack and Avalanche Discussion

<p>Strong winds are blasting the mountains around Bozeman, Big Sky and West Yellowstone, drifting snow onto weak layers buried 6-18” deep and making human-triggered avalanches possible. The Big Sky and Taylor Fork areas received 2” of new snow last night providing a little more ammunition for the wind. Yesterday, Doug got blasted by blowing snow in his <a href="https://www.youtube.com/watch?v=Yaw6TM1HXIE"><strong>video</strong></a&…; discussing instabilities related to wind-loading in the northern Bridger Range. Way to go the extra mile, Doug.</p>

<p>Yesterday, a group turned back from snowboarding a steep line in Hyalite Canyon when they found hard wind slabs covering their objective.&nbsp; Sunday, skiers near Flanders Mountain reported shooting cracks and thin wind slabs (<a href="https://www.mtavalanche.com/node/26024"><strong>photos and details</strong></a>). Saturday, four separate groups triggered avalanches breaking 8-18” deep and up to several hundred feet wide in the Bridger Range (<a href="https://www.mtavalanche.com/node/25992"><strong>northern Bridgers avalanches 1</strong></a>, <a href="https://www.mtavalanche.com/node/25997"><strong>2</strong></a&gt;, <a href="https://www.mtavalanche.com/node/25989"><strong>3</strong></a&gt;, <a href="https://www.mtavalanche.com/node/26026"><strong>Mount Baldy avalanche</strong></a>). Similar conditions exist in the mountains from Bozeman through West Yellowstone.</p>

<p>On non-wind-loaded slopes, you will find generally stable conditions but slopes unaffected by the wind are getting harder to find (<a href="https://www.youtube.com/watch?v=nHauGuzZ7pk&amp;list=PLXu5151nmAvT1nrM2…;

<p>Finally, with high temperatures in the mid 40s F and the possibility of light rain at lower elevations, watch for increased moisture in the upper snowpack and isolated wet snow avalanches.</p>

<p>The danger is MODERATE. Avoid slopes with signs of recently wind-drifted snow and instabilities like cracking or collapsing and test the snowpack before considering steep terrain.</p>

<p>Skiers and riders triggered at least five avalanches breaking 12-24” deep last weekend in the mountains around Cooke City (<a href="https://www.mtavalanche.com/avalanche-activity"><strong>avalanche activity list</strong></a>). Additionally, Alex was climbing Scotch Bonnet on Sunday, when he heard a loud “whumph” that communicated the message of unstable snow to him and his partner (<a href="https://www.youtube.com/watch?v=SxPaEcKATts&amp;list=PLXu5151nmAvT1nrM2…;). The two inches of new snow will not significantly change stability. But winds are gusting to 40 mph from the southwest are drifting snow and exacerbating the existing instabilities related to persistent weak layers in the top two feet deep in the snowpack.</p>

<p>While smaller slides related to wind-drifting are the most likely problem today, dangerous avalanches like the last week’s slide on Mount Abundance and the recent fatal avalanche near Miller Mountain remain possible (<a href="https://www.youtube.com/watch?v=qC7geA4kgyg&amp;list=PLXu5151nmAvT1nrM2… Mountain fatality video</strong></a>, <a href="https://www.youtube.com/watch?v=LHkbEAf1rlM&amp;list=PLXu5151nmAvT1nrM2…. Abundance video</strong></a>, <a href="https://www.mtavalanche.com/node/25941"><strong>details</strong></a&gt;). Turn back if you notice any signs of instability and dig down to test weak layers buried a couple of feet deep.</p>

<p>Today, the danger will be most acute on slopes with recent or ongoing wind-loading. The danger is MODERATE.</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>website<…;, email (<a href="mailto:mtavalanche@gmail.com"><strong>mtavalanche@gmail.com</strong></a…;), phone (406-587-6984), or Instagram (#gnfacobs).</p>

Upcoming Education Opportunities

See our education calendar for an up-to-date list of all local classes. Here are a few select upcoming events.

March 4, Companion Rescue Clinic with the Bozeman Splitfest. Information and registration HERE.