Avalanche Incidents

Northern Madison
Buck Ridge
Sled triggered large avalanche, McAtee Basin
Incident details include images
Buck Ridge
AMu-R2-D2-O
Elevation: 9,200
Aspect: N
Coordinates: 45.1723, -111.4430
Caught: 0 ; Buried: 0

From obs: "Saw this slope which frequently slides had been triggered on our way out last night. Slid to the ground but I expect it was mostly new snow was there is a larger old crown visible further uphill.... I did see two other small pocket slides yesterday also in new snow on bed surfaces of older slides.... General snowpack is getting very deep now but a thick junk layer remains at the ground everywhere I dug sleds out."


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Southern Madison
SOUTHERN MADISON RANGE
Skier triggered wind slab, S. Madison
Incident details include images
SOUTHERN MADISON RANGE
SS-AS-R2-D2-S
Elevation: 10,000
Aspect: E
Coordinates: 44.9786, -111.4150
Caught: 0 ; Buried: 0

From obs: "We were skinning up Pyramid Point from the East. as we approached 10,000 ft, we encountered a wind slab on an East Facing slope. it was about 1-2 inches where we encountered it but it quickly propogated. the crown was 18-20 inches at its highest and about 150 feet wide. the debris ran for about 200 feet."


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Northern Madison
Middle Basin
Small skier triggered wind slab in Middle Basin
Incident details include images
Middle Basin
SS-ASu-R1-D1
Coordinates: 45.3426, -111.3840
Caught: 0 ; Buried: 0

From obs: "On Friday, my partner and I went into Middle Basin with the objective of skiing Middle Peak, and possibly the short couloir that splits the face. That morning we dug a pit on the east facing aspect of the beehive/middle basin ridge (ECTx). Encouraged by our results, we continued on to the base of middle peak and dug another pit (ECTp 30) on the south-facing ice crust. We continued on to summit middle peak and ski down the face to the entrance of the couloir, we descended 20ft into the entrance on soft loose snow and dug our third pit (ECTx), we replicated our results and decided the feature would be safe to ski. At ~1pm the first skier descended the slope, and triggered a small windslab (4-8in and 20ft wide) about 100ft down the slope and skied away uncaught. Skier 2, descended a lower angle slope to the east."


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Northern Gallatin
Flanders Creek
Small soft slab triggered on Mummy (Flanders Side)
Incident details include images
Flanders Creek
SS-AFu-R1-D1-S
Aspect: N
Coordinates: 45.4473, -110.9420
Caught: 0 ; Buried: 0

We left the car with subdued expectations this morning, but were happy to find the new snow bonding well where it hadn’t been slab-ified by the wind. Near the top of Mummy’s North Couloir a shallow (<6”) soft slab broke at my feet as I was wallowing up the boot pack and ran a decent way down the gully- harmless in that spot but with more exposed terrain above we turned tail and enjoyed some excellent skiing.


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Northern Gallatin
Mt Blackmore
Skier Triggered Avalanche, Mount Blackmore
Incident details include images
Mt Blackmore
SS-AS-I
Elevation: 10,000
Aspect: SE
Coordinates: 45.4444, -111.0040
Caught: 0 ; Buried: 0

From email: "On our way out (from Alex Lowe Peak) we watched two skiers climbing to the top of a gully on the SE face of Blackmore... When I looked up again 5 minutes later, the gully had slid. Luckily, based on their tracks it looks like they triggered it from the top without getting caught and then skied it. The first skier was already at the bottom and the second was on his way down."


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Northern Gallatin
Alex Lowe Peak
Skier Triggered Avalanche, Alex Lowe Peak
Incident details include images
Alex Lowe Peak
SS-ASc-R2-D1.5-I
Elevation: 9,700
Aspect: E
Coordinates: 45.4272, -111.0140
Caught: 1 ; Buried: 0; Killed: 0

Write up from the party:

I am writing to report a slide near Alex Lowe Peak, a little before noon today, Sunday March 21, approximately here: 45°25'34.1"N 111°00'47.0"W, on an east facing slope at around 9,700 ft. The nuts and bolts are: The entire slide path was about 500 vertical feet, perhaps 200 feet wide at its widest. The crown looked to be between 8” and 12” deep. One skier caught, not buried, no injuries. All is good.

Here’s the story to go with it if you care to read. Sorry it’s a long one; I am processing.

We approached from the Blackmore/Elephant saddle and headed towards the bowl just south of Alex Lowe Peak. At around 9,450 ft we stopped to do an ECT and got nothing to move. Still skeptical about how the new snow was bonded to the old snow, we also did a propagation saw test at that interface and got the new snow to budge only after cutting 95% through. The interface felt relatively sticky and the new snow did not slide off the column.

We resumed our ascent, moving south around a rocky outcrop, and then north ‘till we were just about above the outcrop. We had thought about continuing north across the bowl to reach the tree-covered east ridge (it is the way my partner approached it many years ago) but the idea of crossing the bowl above rock outcroppings was not enticing so I instead cut west, directly up the fall line (the bowl is not that steep there). When it got a bit steeper, I starting moving slightly south of west (north would have taken me above the rocks again). My thought was to gain the ridge as soon as possible, and then travel on the relative safety of the ridge. After climbing another 150 feet I felt a startling large whumph. I relaxed for a split second because nothing seemed to be moving but my partner told me “heads up” and when I did look up I realized that the trigger had propagated about 150 feet upslope, to near the ridge. By then, snow was already sliding towards me and I had little time to react. I assessed that the sliding snow was not very deep and not moving very fast and decided to try and dig my edges in. It worked for a second but eventually knocked me off my feet. I glided helplessly past my partner, who had been waiting a 100 feet behind on the skin track. He did not get caught. I slid about 250 vertical feet, to near where had done our ECT. I never picked up too much speed and had plenty of time to think about doing what I could to stay on the surface (kind of star-fished on my back seemed to work). The snow was relatively dense but not cohesive. When the sluff started to slow down to a stop I stood up as tall as I could to hopefully keep my head above snow. Turns out it never got higher than my thighs and I was able to get out with little effort. There is an annotated picture below.

In trying to analyze what we did right and/or wrong I believe that our biggest mistake was to underestimate the effect of wind loading near the ridge, and the fact that the new/old snow interface could be (was) vastly different 250 feet higher in elevation. Ironically, last week after touring in Beehive I personally reported isolated wind slabs, which maybe what got me today. My partner expressed that for him, it was the failure to factor in the “new snow,” having been lulled into a misguided sense that we have now transitioned into spring skiing with a hard settled base. The fact that we do not share the same view may be an indication that we are not communicating as well as we should. Anyhow, what I think we did right was to be continually assessing the “what-ifs” as we were choosing our line of ascent. I think it is what saved us from any serious consequences. I basically slid down the hill on a giant snow couch until I came to a stop. Still, it was an unsettling experience.

Incidentally, on our way out we watched two skiers climbing to the top of a gully on the SE face of Blackmore, which made me nervous. When I looked up again 5 minutes later, the gully had slid. Luckily, based on their tracks it looks like they triggered it from the top without getting caught and then skied it. The first skier was already at the bottom and the second was on his way down. Maybe you will get a report from that in your mailbox too."


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Cooke City
COOKE CITY
Snowmobile Triggered Avalanche, East of Cooke City
Incident details include images
COOKE CITY
SS-AM-R1-D1.5
Coordinates: 45.0202, -109.9380
Caught: 0 ; Buried: 0

A rider cut across the slope a couple of times before triggering a small, but deep wind-slab


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Northern Madison
Buck Ridge
Third Yellow Mule / Skier triggered slide + sympathetic
Incident details include images
Incident details contain video
Buck Ridge
SS-ASu-R3-D2-O
Aspect: NE
Coordinates: 45.1912, -111.4430
Caught: 0 ; Buried: 0

https://www.instagram.com/p/CL4xIk5n8PZ/

Sled Skiing in Third Yellow mule... after an air onto the slope the impact from landing resulted in a fracture and failure to / near the ground... in addition, a remote trigger occurred on adjacent slope... 200-300 ft to the skiers right. No body was caught in either slide. Skier that initiated failure was moving at high speed and was beyond slide path before majority of snow movement began. 2 pits where dug prior to riding terrain. One on adjacent slope, we went through to ECT 30 and continued to hammer on the column through 40 wacks of double fist, full force before failure occurred 30 cm above ground. Second pit was dug on slope where slide was initiated... same results, very hard to get failure to occur. Snowpack depth varied from 125 - 180 cm in the area... our pits were dug in depths of around 125 cm and 170 cm respectively.


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Southern Madison
Cabin Creek
Snowbike triggered avalanche, Red Canyon near W. yellowstone
Incident details include images
Incident details contain video
Cabin Creek
HS-AMu-R4-D2-O
Coordinates: 44.8949, -111.2280
Caught: 0 ; Buried: 0

Riders triggered this slide on 2/28/21 near Red Canyon/Cabin Creek, north of West Yellowstone. Nobody caught or injured, but close call.


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Bridger Range
BRIDGER RANGE
Skier triggered cornice N of Peters Point, adjacent to Bridger Bowl boundary
BRIDGER RANGE
SS-ACu
Coordinates: 45.8512, -110.9480
Caught: 0 ; Buried: 0

From obs: "Observed a small avalanche while teaching a rec. 1 today for MSU. The light was too flat to see a crown. Based on the light wind, ski patrol obs. and our moving obs., I hypothesize that it was a dry, loose avalanche. L-N-R1-D1.5-I."

Patrol reported: "A midday report from [a skier] that he had released the Duane's Cornice (out of bounds to the north) as he travelled to the ramp had us looking for any tracks below, none were observed. It looked to step down and pull some older layers as it went through the lower pinch."


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Northern Madison
McAtee Basin
Snowmobile triggered Avalanches (2), McAtee Basin
Incident details include images
Incident details contain video
McAtee Basin
HS-AMu-R3-D2-O
Elevation: 9,600
Aspect: NE
Coordinates: 45.1769, -111.4520
Caught: 0 ; Buried: 0

From obs: "Triggered a large slide with a snowmobile. Went all the way to the ground. Crown seemed to range anywhere from maybe 3 ft to 10 ft. Large slabs of snow broke free and slid for about 100 yards."

A second sled-triggered slide occurred Saturday (2/20) on the ESE facing slope at the entrance to McAtee Basin. SS-AMu-R3-D2-O


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Cooke City
Crown Butte
Snowmobile Triggered Slide on Crown Butte
Incident details include images
Crown Butte
SS-AMu-R2-D2
Coordinates: 45.0525, -109.9620
Caught: 0 ; Buried: 0

Snowmobile triggered slide on Crown Butte, 2/18/2021. 


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Northern Madison
Beehive Basin
Splitboarder triggered, caught and killed in Beehive
Incident details include images
Incident details contain video
Beehive Basin
HS-ARu-R4-D2.5-O
Elevation: 9,100
Aspect: SW
Coordinates: 45.3269, -111.3840
Caught: 2 ; Buried: 1; Killed: 1

On February 14, 2021, two splitboarders triggered an avalanche in Beehive Basin north of Big Sky. They were skinning up the slope when they triggered the avalanche. Both members of the party were caught, but Boarder 1 was able to grab trees and not be buried. Boarder 2 was carried approximately 300 feet downslope where he hit a tree and was critically injured. He was partially buried, entangled around a tree with his head downhill. Boarder 1 heard his partner’s screams, called 911 and went to his aid. He administered first aid and worked to keep him warm and calm. Gallatin County Sheriff Search and Rescue in Big Sky (GCSAR) left the trailhead within 45 minutes of the 911 call, skied to the scene and began providing care. A GCSAR helicopter arrived soon afterward and the injured boarder was short hauled to Big Sky Fire Department and medical care. Boarder 2 died from his injuries that night. The avalanche was 300 feet wide, 500 feet vertical and averaged 2 feet deep. It broke on a layer of facets and near the ground. Read the full accident report here: https://www.mtavalanche.com/accident/21/02/16


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Cooke City
Daisy Pass
Snowmobile triggered small slides near Daisy Pass
Incident details include images
Incident details contain video
Daisy Pass
SS-AMu-R1-D1.5
Elevation: 9,950
Aspect: SE
Coordinates: 45.0497, -109.9640
Caught: 0 ; Buried: 0

Saw 2 recent HS-AM-R1-D1 Henderson Ridge, close to Daisy, SE, >35* 9950’ 45.0536, 109.9524


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Southern Madison
Cabin Creek
Snowmobile triggered slides in Cabin Creek
Incident details include images
Cabin Creek
SS-AMu-R3-D2-O
Coordinates: 44.8949, -111.2280
Caught: 0 ; Buried: 0

On 2/13/21 riders reported they triggered this avalanche, and remotely triggered two other slides. Nobody was injured. One partially buried.


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Lionhead Range
Lionhead Ridge
Snowmobile Triggered Slide on Lionhead Ridge
Incident details include images
Lionhead Ridge
SS-AMu-R3-D2-O
Elevation: 9,500
Aspect: NE
Coordinates: 44.7145, -111.3180
Caught: 0 ; Buried: 0

Snowmobile triggered slide on Lionhead Ridge in Upper Watkins drainage on 2/11/2021. Appears to have broken on weak snow near the ground. 


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Southern Gallatin
Portal Creek
Remotely triggered avalanches in Portal Creek
Incident details include images
Portal Creek
SS-AMr-R2-D2-O
Coordinates: 45.2890, -111.1410
Caught: 0 ; Buried: 0

On Thursday, Feb 11, snowmobilers remotely triggered two large avalanche in the Portal Creek area.

From obs: "Broke on lookers right crown first then triggered second slide to lookers left (rocks everywhere). Broke on depth hoar on both slides north facing aspects. Nobody was caught."


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Cooke City
Sheep Creek
Sheep Creek - Gully east of Miller Trees
Incident details include images
Sheep Creek
SS-ASu-I
Elevation: 9,100
Aspect: E
Coordinates: 45.0396, -109.9750
Caught: 0 ; Buried: 0

From Obs: "Skiers traveling on South facing slope at 9,100ft elevation ascending Miller Trees remote triggered from skin track (second lap) a wind slab slide on a steeper East facing slope that slid to gully floor and out to Sheep Creek. Westerly wind was blowing with gusts carrying snow to load the east-facing side of the gully. Crown was approximately 4ft at the crest of the gully’s slope. Cracking visible in the photo from skin track traveled up to crown 50yrds away. Pit dug at similar elevation on South facing slope yielded slight cracking within the storm slab but no propagation (ECT16N)."


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Lionhead Range
LIONHEAD AREA
Snowmobile triggered near Lionhead
Incident details include images
LIONHEAD AREA
SS-AMu-R3-D2-I
Elevation: 8,000
Aspect: S
Coordinates: 44.7292, -111.3230
Caught: 0 ; Buried: 0

Riders wrote that they triggerend an avalanche on a south facing slope in West Targhee Creek on 2/6/21. No one was caught.


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Cooke City
Woody Ridge
Skier triggered and partially buried on Woody Ridge
Incident details include images
Woody Ridge
SS-ASu-R2-D2-I
Elevation: 9,000
Aspect: NE
Coordinates: 44.9739, -109.9240
Caught: 1 ; Buried: 0

A 100’ wide by 12”-24” deep avalanche was triggered by a skier on a North East aspect of Woody Ridge at 9000’. From reporting group: "Skier was carried and partially buried after arresting on a tree. The area was short pitches with rollovers and pillow/shelf features. Once the skier was in avalanche terrain the wind loaded storm slab released exposing a faceted layer which the new snow had not bound with. The release occurred where the slope went from 20 degrees to 30 degree terrain. A pit dug the previous day (2/4/2020) on the same slope resulted in an ECT 50 + and a CT 38. Afterward that day we proceeded up the ridge to find wind slabs formed at the top of the ridge which would release when cut. Today, the snow felt stable on the ascent through trees and on tree covered ridges. When we turned around in what we considered “mellow”/“putt putt” terrain due to an intensifying storm and the day becoming late we skied through some exposed ridges and drops. First skier saw no avalanche activity through broken up terrain. Second skier triggered the slide on the first turn. After the event a third skier skied the tree covered ridge used for the ascent and was clear. Whompfing was observed in the trees below the pillows after the event..."


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Lionhead Range
LIONHEAD AREA
Snowmobiler triggered avalanche, Lionhead
Incident details include images
LIONHEAD AREA
SS-AMu-R2-D2-O
Elevation: 9,400
Aspect: SE
Coordinates: 44.7310, -111.3880
Caught: 0 ; Buried: 0

A snowmobiler triggered this avalanche, no one was caught. From the reporting party, "We were playing in the trees below the ridge and we climbed up to the left in that little meadow and that's when the slide broke to our right and propagated up. From what I can tell is it broke on two layers and it was approximately 100ft wide and ran 500ft. Debris piled up in the trees above the meadow we were playing in."


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Southern Madison
Ernie Miller Ridge
Skiers remote triggered very large slide Ernest Miller Ridge
Incident details include images
Ernie Miller Ridge
HS-ASr-R4-D2.5-O
Elevation: 9,700
Aspect: E
Coordinates: 44.9560, -111.1320
Caught: 0 ; Buried: 0

From group: "We skinned into the Ernest Miller Ridge area this morning around 8:40am. There was 18-24 inches of fresh storm snow in the bacon rind creek area. As we skinned in, we observed whoomphing and cracking throughout the basin. We ascended right of the normal trail in mellower terrain to the lower bench area. We took a break there and after discussion of the terrain and safe areas to ascend were getting ready to head to the far lookers left trees. A giant collapse happened as we were standing there and sent an almost shockwave like effect up the hill, small ripples and cracks formed way above and away from us and the entire face of Ernest Miller Ridge ripped out and ran the distance of the ridge. We were out of the way of any runout zone and away from the face so in a safe space. It was the largest remote trigger that I have ever experienced and witnessed out in the field."

"Where we triggered the slide, the slope was about 24 degrees, it then triggers on 30ish degrees and then sent the rest of the basin."


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Southern Madison
Taylor Fork
Snowmobile Triggered Avalanche, Sunlight Basin
Incident details include images
Taylor Fork
SS-AKu-R2-D2-O
Elevation: 8,800
Aspect: N
Coordinates: 44.9695, -111.2920
Caught: 0 ; Buried: 0

A snowmobiler triggered an avalanche while side-hilling. No one caught or injured. The debris was estimated to be 8' deep. 


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Cooke City
COOKE CITY
Snowmobiler caught and uninjured in avalanche, Cooke City
Incident details include images
COOKE CITY
AMu
Aspect: S
Coordinates: 45.0202, -109.9380
Caught: 1 ; Buried: 0

CCMS called and said a rider triggered a slide about 1/4 mile north of Huckelberry Lake on a south facing slope. It trashed a rental sled. The rider was at the crown when it broke and was above most of the debris. He was only buried to his knees and was uninjured. No details on size or depth of slide. A close call.
 


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Cooke City
Sheep Mountain
Snowmobile triggered on Sheep Mtn, Cooke
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Sheep Mountain
SS-AMu-R2-D2-O
Elevation: 9,800
Aspect: S
Coordinates: 45.0722, -109.9280
Caught: 0 ; Buried: 0

Snowmobilers triggered two avalanches on 1/22/2021. A group of 11 were climbing on the southside of Sheep Mountain. The slides were triggered by two separate riders.


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Cooke City
Sheep Creek
Snowmobile Triggered Avalanche, Sheep Creek
Sheep Creek
SS-AMu
Coordinates: 45.0344, -109.9840
Caught: 0 ; Buried: 0

A group of seven riders in Sheep Creek triggered one avalanche and observed two more. The slide failed 1' deep likely on surface hoar. No one was buried or injured. 


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Cooke City
COOKE CITY
Skier and Snowmobile Triggered Avalanches, Cooke City
Incident details include images
COOKE CITY
SS-AS-R2-O
Elevation: 9,500
Aspect: S
Coordinates: 45.0202, -109.9380
Caught: 0 ; Buried: 0

A skier near Goose Lake observed two human triggered avalanches, one looked to be skier triggered and one looked to be snowmobile triggered. Solar aspects around 9500'. The skier dug at pit and found at least one failed on buried surface hoar


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Northern Madison
Buck Ridge
Snowmobile Triggered Avalanche, Second Yellowmule
Incident details include images
Incident details contain video
Buck Ridge
SS-AM-R1-D1.5
Aspect: N
Coordinates: 45.1719, -111.3800
Caught: 0 ; Buried: 0

Snowmobile triggered avalanche on a north-facing slope in Second Yellowmule. Likely occurred on 1/18. 


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Lionhead Range
Lionhead Ridge
Many snowmobile triggered slides at Lionhead
Incident details include images
Incident details contain video
Lionhead Ridge
SS-AMu-R2-D2-O
Elevation: 9,000
Coordinates: 44.7145, -111.3180
Caught: 0 ; Buried: 0

Many snowmobile triggered avalanches were observed after new snow overloaded a very weak snowpack.


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Centennial Range
CENTENNIAL RANGE
Sledder triggered slide and 2 naturals in Centennials
Incident details include images
CENTENNIAL RANGE
SS-AM-R2-D2
Coordinates: 44.5476, -111.5250
Caught: 0 ; Buried: 0

From obs: "...Two natural slab avalanches on north aspect of Reas Peak, one from recent storm and one from previous storm. Photo is from a snowmobile triggered avalanche from 1/9/21, you can see the party and one of the members riding the adjacent slope."


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Northern Gallatin
Flanders Creek
Skier triggered large slide on Flanders Mountain
Incident details include images
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Flanders Creek
HS-ASu-R4-D2.5-O
Elevation: 9,800
Aspect: E
Coordinates: 45.4359, -110.9440
Caught: 0 ; Buried: 0

From obs: "We dug a pit and found a really weak snowpack! Regardless of the poor stability result, we proceeded to ski an East facing bowl south of Flanders Mountain knowing that the slope angle was low and only flirted with 30 degrees in some parts of the bowl. We could have chosen to ski the trees further to our left, but after evaluating the consequence associated with skiing the bowl, we decided that the center of the bowl did not pose too big a risk given we skied one at a time. My partner skied first, he skied practically all the way back to the skin track when the slope failed and the entire bowl released. He was pretty well out of the way of danger by the time the bowl began to move. From our perspective, the trigger happened at the bottom of the slope.... The bowl was not the only slope that slid, the avalanche propagated around the ridge and released a slide on the more south-easterly facing aspect just south of the bowl. We tail-tucked and went home glad no one was caught or hurt."

GNFAC forecasters visited the site on 1/11/21. We measured the maximum slope angle in the start zone at 35 degrees with an average slope angle of 33 degrees. The debris in each path was up to 2-3 meters deep. The avalanche broke on a layer of weak faceted snow 70 cm above the ground, and propagated almost 1000 feet wide. The crown was 2-3 feet deep.


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Cooke City
Skier Triggered Avalanche near Meridian Peak
Incident details include images
SS-ASu-R2-D1.5
Elevation: 9,350
Aspect: SE
Coordinates: 45.0270, -110.0030
Caught: 1 ; Buried: 0

From observation (1/8/21): "Skier triggered slide from someone outside our group lower in Silver Creek 9350’ S facing 18-24” deep 60-70’ wide. Ran 500’ skier was able to regain skis and off slab 100’ below initiation."


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Cooke City
The Fin
Skier triggered, caught and injured on The Fin
Incident details include images
Incident details contain video
The Fin
SS-ASu-R2-D2.5-O
Elevation: 9,700
Aspect: E
Coordinates: 45.0046, -109.9580
Caught: 3 ; Buried: 1

FULL AVALANCHE REPORT: https://www.mtavalanche.com/accident/21/01/11

On January 8, 2021 a group of six skiers triggered an avalanche on The Fin on Republic Mountain outside of Cooke City. They were skinning up the slope when they felt the slope collapse and watched cracks propagate 250’ upslope. Three were caught and partially buried. Skier 1 deployed his airbag, was partially buried and able to get himself free. He freed himself from the debris and began a beacon search which led him to see skier 2 who was buried head down with his airway obstructed. He was uncovered by skier 1, not breathing and unconscious. He sustained injuries, but later made it out under his own power. Skier 3 was partially buried higher in the path, sustained serious injuries to his ribs and lungs and was evacuated by helicopter. The avalanche broke 1.5’- 2’ deep, 200’ wide and ran 700’ vertical. The average slope angle was 37 degrees. Slope angle at the crown was 33 degrees on an east aspect at 9,700’ elevation. The avalanche is classified SS-ASu-R2-D2.5-O.


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Northern Madison
Buck Ridge
Rider triggered large, wide slide on Buck Ridge
Incident details include images
Incident details contain video
Buck Ridge
HS-AMu-R4-D2-O
Elevation: 9,350
Aspect: NE
Coordinates: 45.1719, -111.3800
Caught: 0 ; Buried: 0

We saw this relatively very large, full width avalanches that was triggered on January 7, 2021. It broke on weak, sugary snow below hard wind drifted snow and recent new snow.


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Northern Madison
Buck Ridge
Snowmobile triggered slides (2) on Buck Ridge
Incident details include images
Buck Ridge
HS-AMu-R3-D2-O
Elevation: 9,300
Aspect: NE
Coordinates: 45.1719, -111.3800
Caught: 0 ; Buried: 0

We saw two large snowmobile triggered avalanches (and one very large, in separate record) that occurred on January 7, 2021. They broke on weak, sugary snow below hard wind drifted snow and recent new snow.


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Northern Madison
Buck Ridge
Snowmobiler triggered avalanche on Buck Ridge
Incident details include images
Buck Ridge
SS-AM
Coordinates: 45.1719, -111.3800
Caught: 0 ; Buried: 0
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Out of Advisory Area
Jardine
Remotely triggered avalanche on Bald Mountain, Jardine, MT
Jardine
Coordinates: 45.0932, -110.5690
Caught: 0 ; Buried: 0

On a wind loaded, rocky slope off the summit of Bald Mountain we triggered a remote slide about a 100 across from us while skiing. Conditions elsewhere in the area were decent, but the exposed, wind loaded slopes showed activity with whoomping and cracks, and the one avalanche. None where hurt or caught. Conditions were as advised in the avalanche report.


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Northern Madison
Skier remotely triggered avalanche in N. Madisons
Incident details include images
SS-ASr-R3-D2
Coordinates: 45.2615, -111.3150
Caught: 0 ; Buried: 0

"Shallow snowpack 24-36” from 6800-9200 ft S and E aspect. Facets on the ground 6-12” deep. Widespread collapsing and cracks all the way on low angle terrain to the top. Big shooting crack across the south facing path from the skin track so expected the east bowl to remotely trigger and it did from 25m away on the ridge. R3D2 slide. Confirms all previous regional reports and the concerns of the day, typical in this specific area early season. Obsessive terrain management is the only way just now."


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Bridger Range
Bradley Meadow
Skier triggered avalanche in Bradley's Meadow
Incident details include images
Bradley Meadow
SS-AS-R1-D1.5
Elevation: 8,000
Aspect: S
Coordinates: 45.8322, -110.9280
Caught: 0 ; Buried: 0

I was skiing down the apron at Bridger and noticed this slide on Bradley's that appeared to be skier triggered. Picture's were taken at about 2pm. I don't believe this activity was there when I came down the apron earlier in the day around 11:45. I talked to patrol about it and they had not heard anything about it at the time. It appeared both tracks going in, came out. Thanks for all the work you guys do!


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Out of Advisory Area
Human triggered avalanche in AB wilderness near Paradise Valley
SS-ASu
Caught: 0 ; Buried: 0

From an IG message:

A person remotely triggered a large avalanche 200' wide and 800' slope distance on 1/5/21. The crown was 2' thick and broke on depth hoar which is on most slopes above 8,000'. No one was caught.


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Cooke City
Henderson Bench
Skier triggered avalanche on Henderson Mtn
Incident details include images
Henderson Bench
SS-ASr-O
Elevation: 9,500
Aspect: S
Coordinates: 45.0408, -109.9400
Caught: 0 ; Buried: 0

Remote triggered a soft slab with a ski cut. Cut across top of slope and the slide initiated ten yards below. slide was approximately 25 feet at the crown and ran the whole length/ width of the gulley. Couldn’t see past the choke of the gulley . Thicker at the crown where snow was wind drifted 16 in~. Dug a quick pit after. HS 80 cm. Slab on top of crust and facets. No one was caught and we skinned back up and skied out our original skin track.


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Northern Gallatin
Hyalite - main fork
Ice Climber triggered avalanche in Avalanche Gulch, Hyalite
Hyalite - main fork
SS-AFu
Elevation: 9,200
Aspect: W
Coordinates: 45.4472, -110.9620
Caught: 0 ; Buried: 0

A first person account: "Human triggered avalanche at (estimate) 1:30pm from upper 'Avalanche Gulch' by one party descending from 'Dribbles'. Climber on second moderate pitch of 'Avalanche Gulch' swept but saved by screw placement from going over pitch 1 of Avalanche Gulch. No injuries, no burials, and both parties reconvened at base of Avalanche Gulch to assess the event. All parties descended at 3pm."

More info:

We were looking around for 'Responsible Family Men' and caused the avalanche crossing the gully perhaps ~200+ ft up from the snow ramp on AG. We immediately hoofed it downslope after the slide occurred to see if there were folks caught up in it, and assist if at all possible. Thankfully it went as it did. I would estimate that the wind around Dribbles was 5-10, gusting 20-25. 
 

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Out of Advisory Area
Abiathar Peak
Skier triggered 2 wind slabs on Abiathar
Incident details include images
Abiathar Peak
SS-ASu-R2-D1.5-I
Elevation: 10,500
Aspect: N
Coordinates: 44.9756, -110.0310
Caught: 0 ; Buried: 0

Skiers triggered a wind slab while ascending the north couloir on Abiathar Peak on 1/2/21. On their descent they triggered another similar sized slab. They were not caught or injured, and felt lucky to "dodge a bullet". 

From email: "We approached Abiathar north cirque intending to climb and ski the north couloir. Two extended column tests were performed and it was determined that the main threat was new snow on shallow facets... At approx 10,500' the first member of our party released the first slab, so we pulled the plug and began to prepare for descent. Upon descent, I dropped first and faded left to eddy out behind a rock outcrop and released the second slab, which broke just upslope of me. I was able to edge into the bed surface and the slab ran past without incident."


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Out of Advisory Area
Pebble Creek - YNP
Skier remote triggered in YNP near Cooke
Incident details include images
Pebble Creek - YNP
SS-ASr-R2-D2-O
Elevation: 9,100
Aspect: SE
Coordinates: 45.0254, -110.0310
Caught: 0 ; Buried: 0

Skiers triggered a slide remotely, from low angle terrain, on a 9100’ SE aspect. It was a 1.5'-2' deep soft slab (4F+ to F hard) that broke on weak sugary facets.

From obs: "Did a test pit at same elevation 30’ away on S asp in thin area (HS70cm).  ECTN6 down15 on new snow interface & ECTN 16 down 35 on the 4F+DF/RG : F, FC interface.  We skinned around to the shoulder heard/felt a whumph (similar magnitude/duration/est. dist prop to other whumphs occurring in the last 2 days) and saw the avalanche. Trigger distance ~15’ from first person."


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Bridger Range
Saddle Peak
Skier triggered large slide on Saddle Peak
Incident details include images
Incident details contain video
Saddle Peak
HS-AS-R2-D2.5-O
Elevation: 9,000
Aspect: NE
Coordinates: 45.7943, -110.9360
Caught: 0 ; Buried: 0

On January 1, 2021 at approximately 1530 a skier triggered an avalanche on Saddle Peak south of Bridger Bowl. He left from the ski area around 1445 and skin up the ridge out of bounds to the south. Shortly after, patrol witnessed the avalanche and then later saw the solo skier returning to the ski area after descending the bed surface of the avalanche. The skier reported the event to patrol when he returned. He stomped at the rollover below the summit, on the south end of the low angle ridge, and it broke 3 ft deep....ran down north central and the main face.


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Cooke City
Crown Butte
Crown Butte, Snowmobile triggered Avalanche
Incident details include images
Incident details contain video
Crown Butte
SS-AMu-R2-D2-O
Elevation: 9,800
Aspect: SE
Coordinates: 45.0525, -109.9620
Caught: 0 ; Buried: 0; Killed: 0

A snowmobile triggered avalanche broke 1-2' deep on a layer of near surface facets sandwiched between two crusts. 


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Northern Gallatin
Mt Blackmore
Skier Triggered Avalanche Mount Blackmore - East Face
Incident details include images
Mt Blackmore
SS-ASu-R1-D1-O
Elevation: 9,500
Aspect: E
Coordinates: 45.4446, -111.0000
Caught: 0 ; Buried: 0

From obs: "Skier Triggered a 1.5' slide to his right while making a turn near a cliff band. The slide did not intersect with the skier's path. We did a ECT before choosing our line and were not able to get the soft slab, or anything else to propagate, but clearly, the slab is ready to go as it slid on rocks. We both skied out without incident."


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Northern Madison
Buck Ridge
Three sledder triggered slides off Buck Ridge
Incident details include images
Incident details contain video
Buck Ridge
SS-AMu-R2-D1.5-O
Elevation: 9,000
Aspect: SE
Coordinates: 45.1719, -111.3800
Caught: 0 ; Buried: 0

During our field work today (12/29) we noted 3 avalanches:

1. On the north of the ridge before the Yellowmule Weather Station. It was small sized, wind-loaded and broke on facets. Guessing R2, D1.5.

2. 3rd Yellowmule we saw another small slide (R1, D1.5) on a wind-loaded slope that broke on facets.

3. We saw our third slide as soon as we turned down the hill from 3rd YM to MacAtee Basin. It was small (R1, D1) and broke to the ground on facets. It was a steep hill.

All three slides were likely triggered from the bottom on Sunday (12/27), were small and did not propagate far.


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Bridger Range
Saddle Peak
Skier Triggered Avalanche - Football Field
Incident details include images
Saddle Peak
SS-ASu-R3-D2.5-O
Elevation: 8,700
Aspect: E
Coordinates: 45.7974, -110.9350
Caught: 0 ; Buried: 0; Killed: 0

A solo skier was doing an annual run from the M to Bridger Bowl but could not enter the resort as normal due to limited terrain openings etc. The skier read the avalanche advisory on the 24th but not on the 25th, the day of the traverse. The skier observed recent avalanches on Bridger Peak and in Argentina Bowl, immediately south of Saddle Peak. He did not observe other signs of instability or dig pits but mentioned that travel was generally on non-snow-covered ground. Arriving at the ski area boundary, he was concerned about the avalanche danger and decent route but decided that going down the Bitter End run at the Bridger Bowl Boundary and getting on to the lower angle prow on the ski area boundary would be the best option. He made jump turns down to the steep convexity 50’ below the ridge. The slope cracked at his feet and the avalanche initiated 20’ away.

The avalanche propagated at least 500’ wide into the Football Field adjacent to Bridger Bowl's south boundary, and ran down below the cliff band mid-slope. The avalanche was 2’ deep and was a hard slab that failed on depth hoar (SS-ASu-R3-D2.5-O). The skier descended the track and looked for any recent ski or skin tracks that would indicate other skiers in the area. Seeing no recent tracks, the skier went to Bridger Bowl Ski Patrol to report the incident.


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Cooke City
Zimmer Creek
Skier triggered avalanche NE of Cooke City
Incident details contain video
Zimmer Creek
SS-ASu-R3-D2-I
Elevation: 9,800
Aspect: E
Coordinates: 45.0999, -109.8840
Caught: 0 ; Buried: 0

A skier triggered a low angled slope (29-30 deg). It was new snow that failed on a layer of graupel. Crown was 6” to 2’ at its deepest. Broke 400’ wide, maybe 200’ vert. The skier triggered the slide on descent and was not aware of the avalanche until he stopped at the bottom of the run. Skier had a partner, rescue gear and was not caught.


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Northern Madison
Beehive Basin
Skier triggered large cornice, Beehive
Incident details include images
Beehive Basin
C-ASu-R2-D2-O
Elevation: 8,960
Aspect: E
Coordinates: 45.3275, -111.3970
Caught: 0 ; Buried: 0

From obs.: "Kicked off a larger than expected cornice as we skinned up the ridge on the W side of Beehive basin. Wind was blowing 20-ish across the opening, cornice had grown pretty good-sized for so little snow. I was making a turn on skins to get back away from the edge when the cornice gave way, probably pulled 25 feet end to end and broke a good 5 feet back from the lee edge of the cornice. I was able to get off the cornice and avoid going over the edge. No activity on the slope below after cornice drop,... although there was a decent hard slab that pulled out just below the ridge when the cornice dropped onto it.... Hard slab on the edges was about 10" deep, some big chunks of cornice on the slope for any future riders..."


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Bridger Range
BRIDGER RANGE
Skier triggered avalanche at Bridger Bowl
Incident details include images
BRIDGER RANGE
SS-ASu-R2-D1.5-I
Elevation: 7,500
Aspect: NE
Coordinates: 45.8512, -110.9480
Caught: 0 ; Buried: 0

From obs. on 12/2/2020: "...a skier triggered avalanche... at Bridger Bowl (Schlasmans Lift) from this afternoon. I was skinning up the N subridge to the lookers right of the lift and some skiers above me triggered a wind slab on faceted snow that came down almost right on top of me. I had to run on my skins to get out of the way. I dug 3 pits yesterday and got ect1 every time so was up skiing and skinning conservatively which allowed me to get out of the way of the slide in time to avoid being caught and most likely buried. The toe of the slide was all of 6’ deep....

"...There is about a foot of fresh sitting on top of faceted crust that is sitting on top of more facets and another crust, and obvious red flags from wind affect (big ripples, obviously wind loaded slopes, obvious slabs forming that you can break through with your skis)..."


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Bridger Range
Hardscrabble Peak
Small skier triggered slides in Northern Bridgers
Incident details include images
Hardscrabble Peak
HS-ASu-R1-D1
Coordinates: 45.9151, -110.9810
Caught: 0 ; Buried: 0

On 11/12, two small slides were reported in the Northern Bridger Range near Fairy Lake, at least one of which was skier triggered.

The skier triggered slide was "a wind slab approximately 50 X 50’ with a 6” crown. The slab itself was only about 4” thick and only slid about 5” down the slope before stopping, and I was able to stop and then turn around and ski off of the slab without it moving any further. The 4” of dry slab was sitting on about 3” of sugary snow that was on a very firm icy bed surface."

We don't have details on the other slide, but it was reported as a wind slab avalanche on the NE side of Pomp Peak.


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Bridger Range
Bridger Bowl
Skier triggered wind slab at Bridger
Incident details include images
Bridger Bowl
ASu-R2-D1.5-I
Elevation: 7,800
Aspect: NE
Coordinates: 45.8156, -110.9230
Caught: 0 ; Buried: 0

Skier triggered slide on 10/26 at Bridger Bowl near the top of Pierre's Knob lift. Reported via IG story/message.


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