21-22

Sheep Creek Avalanche

Date
Activity
Skiing

SS-ASc-R3-D1.5-I

 

Ski cut on belay a SS avalanche out of the start zone of this N facing slope in Sheep Creek basin. The crown was 4-16" deep and broke into the rocks on skier's right, as well as skirted the bottom of the rock wall skier's left. Winds along the Mineral ridge were moderate gusting strong from the south with active transport observed. 

Region
Cooke City
Location (from list)
Sheep Creek

Five skiers caught in large natural dry loose

East Rosebud
Out of Advisory Area
Code
L-N-R2-D2-S
Aspect
NW
Latitude
45.17210
Longitude
-109.65000
Notes

From one group's obs. 4/16/22: "While 3 of us were on ascent( about 2/3 height) we witnessed a large spin drift off the climbers right wall which entrained a lot of snow turning into a significant dry loose event. Our 3rd who was a little ways behind got carried to the apron. There was a 2nd party behind us just above the apron that followed us up the couloir. Their crew of 4 was carried as well. The 2 of us that weren’t carried went into search with our beacons and skied down the the apron where we found everyone on top and luckily uninjured. We never had communication or visual of the other crew on ascent until moments before the incident." 

Other group's obs. 4/17/22: "Yesterday a natural dry/loose avalanche ran in the Chamonix couloir in East Rosebud, partially burry all four people in my party and one person in a party above us. Four of the five of us were able dig ourselves out and there were no significant injuries.

We knew the area had received a lot of snow in the last week but there was only a four or five inches of fresh snow at the lake. At about 8,700 feet, when we transitioned to boot packing, there was roughly a foot of low density fresh snow that was bonded well to the existing snow. Skies were clear at sunrise, clouds moved in throughout the morning and it began snowing lightly around 11:30.

We didn't see the beginning of the avalanche, two members of the party above us said that a sluff that ran off one of the walls above them and was small enough when it ran past them that it didn't effect them. I don't know how high they were above the third member of their party but the third member was a few hundred feet above us. By the time the avalanche reached us it had grown substantially and was an over-head wall of snow. The two skiers who saw the avalanche start didn't see it step down to any deeper layers, it was just the new snow. Based on the data from my watch, we were carried about 750 vertical feet. We didn't take any photos of the slide."

Number of slides
1
Number caught
5
Number buried
0
Avalanche Type
Loose-snow avalanche
Trigger
Natural trigger
R size
2
D size
2
Bed Surface
S - Avalanche released within new snow
Problem Type
New Snow
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year
21-22

ECTP 21

Date
Activity
Skiing

Fabulous day skiing north of Frazier Basin. East and south aspects had thick supportable crust below 6-15" of new. Bonded well, some sluffing on steeper slopes. Entertained skiing a steeper north facing line but backed off after digging.  Pit on 34 deg North facing slope, 250cm snow. ECTP 21 high energy Q1 shear about 2 1/2 down, well developed facets below thin (N. facing) ice crust. 

Thanks for all you do!!

Region
Bridger Range
Observer Name
Luke Omohundro

Large dry loose triggered from spin drift

Date
Activity
Skiing

While 3 of us were on ascent( about 2/3 height) we witnessed a large spin drift off the climbers right wall which entrained a lot of snow turning into a significant dry loose event. Our 3rd who was a little ways behind got carried to the apron. There was a 2nd party behind us just above the apron that followed us up the couloir. Their crew of 4 was carried as well. The 2 of us that weren’t carried went into search with our beacons and skied down the the apron where we found everyone on top and luckily uninjured.

We never had communication or visual of the other crew on ascent until moments before the incident.  
 

I would classify the avalanche as a dry loose D2. Their was evidence of several small avalanches from previous days in the couloir. Boot pen on ascent was 24-35cm

Region
Out of Advisory Area

GNFAC Avalanche Forecast for Fri Apr 15, 2022

Snowpack and Avalanche Discussion

<p>A cold spring storm this past week brought a return to wintery riding conditions and the attendant avalanche concerns. This weekend won’t be as bitterly cold, but with cloudy skies and temperatures generally remaining below freezing, dry snow avalanches will remain the primary concern.&nbsp;</p>

<p>The issue you’re most likely to encounter are avalanches breaking in the new and wind drifted snow. As the storm rolled in on Monday, a skier in the Bridger Range triggered a small slab in the new snow on a small slope (<a href="https://www.mtavalanche.com/images/22/small-wind-slab-bridger-bowl"><st…;). With substantial storm totals since then, larger and more dangerous slides are now possible. Watch for stiff, punchy feeling slabs and cracks shooting out in front of you as signs that you’ve found a slope where you could trigger a slab avalanche. Winds have blown from almost every direction over the past few days, so keep an eye out for wind loading in unusual areas. If you don’t see obvious signs of instability, dig down to check the interface between the new and old snow (and on cold, shady slopes dig a bit deeper to look for persistent weak layers that may still lurk another 1-3 ft deeper).&nbsp;</p>

<p>A quick break in the clouds or temperatures rising a bit higher than expected would add wet loose sloughs to our list of concerns. The mid-April sun is intense, it’ll only take a few minutes of direct sunshine to dampen and destabilize the snow surface. If the new snow is getting warm and feeling sticky, be on alert because you could trigger a loose wet slide.</p>

<p>Continue to follow safe travel protocols by skiing and riding with a partner, carrying a beacon, shovel and probe and exposing only one person at a time to avalanche terrain.&nbsp;</p>

<p><strong>A Note on Bridger Bowl:</strong> Without the daily avalanche mitigation efforts of the ski patrol, backcountry conditions now exist within the boundaries of Bridger Bowl (<a href="https://www.youtube.com/watch?v=zcTGZm8vnZA"><strong><u>video</u></stro…;). Commonly traveled routes such the North Bowl Road and any slope steeper than 30 degrees are avalanche terrain (i.e. most of the Ridge and Schlasman’s terrain). Other groups above and below you may complicate principles of safe travel.&nbsp;</p>

<p>We will issue spring snowpack and weather updates each Monday and Friday through April, or as needed, and we will share relevant avalanche and snowpack information on our website and social media. 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>

Announcements, Avalanche Education and Events

Bridger Bowl is closed, and backcountry conditions exist. There is no avalanche mitigation or ski patrol rescue. In case of emergency, call 911. Please stay clear of work areas, snowmobiles, chair lifts and other equipment.

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