Avalanche Incidents

Northern Madison
Middle Basin
Skier triggered wet slab, Middle Basin
Incident details include images
Middle Basin
WS-ASu-R3-D2-I
Elevation: 10,000
Aspect: SE
Coordinates: 45.3428, -111.3860
Caught: 0 ; Buried: 0

From (5/17/20): "...WS - ASu - R3 - D2 - I SE face of Middle Basin Peak starting at 10,000' Estimated SZ of 30° Slab depth of about 8". We were out too late in the day and chose to ignore a number of observational warnings. We were lucky and remotely triggered the avalanche below us."


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Bridger Range
The Playground
Skier triggered wet slab The Playground
Incident details include images
The Playground
WS-ASu-R1-D1-I
Elevation: 7,500
Aspect: SE
Coordinates: 45.8411, -110.9390
Caught: 0 ; Buried: 0

Obs (4/17/20): "Today while skiing at the Playground in the Bridgers my party triggered a wet slab on an ESE 33 degree slope at 7,700' (HS-ASu-R1-D1-I). No one was caught or injured. We decided to turn around as the sun was roasting the snow at 11:45 a.m., and picked a low angle slope to ski back to the trail. Skier 2 descended and popped out a slab about 10" thick and 50' wide, but the slide was slow moving at first and he was able to ski away. The slide gained momentum pretty quickly and ran powerfully about 250' down the slope."


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Bridger Range
Bridger Bowl
New Snow Avalanches Bridger Range
Incident details include images
Bridger Bowl
SS-AS-R2-D1.5-S
Coordinates: 45.8156, -110.9230
Caught: 0 ; Buried: 0

From IG "Natural avalanche in the Apron. Ran Full path"

From Email, "We just did one run down Ptarmigan.  Winds were cranking out of the north from about Midway Bridger on higher.  Over on the north side of Bronco, there were some wind drifts that were super sensitive and were cracking and sliding into the skin track easily. While skiing the snow felt pretty upside down, similar to what we were seeing on the skin track.  Did a ski cut as I came up to that first rollover that is often rocky early season and triggered a small avalanche.  It cracked easily and slid, but with the fairly gentle slope angles right below that rollover it stopped pretty quickly.  We only did that one run and with the snow as sensitive as it was I wouldn’t have wanted to go up to the ridge today."

Observed debris from 3 new snow avalanches from the top of Powder Park Lift at Bridger Bowl. Two ran from the Dick's/ Bradley's Rib area across the North Bowl Road and well into North Bowl. One slide on the south edge of Baby Bear came through the trees and stopped 100' above Powder Park Lift. 


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Bridger Range
Bridger Bowl
Long running skier triggered slide in new snow in Bridgers
Incident details include images
Bridger Bowl
SS-ASu-R1-D1.5-O
Coordinates: 45.8156, -110.9230
Caught: 0 ; Buried: 0

From obs on 4/14: "Saw an unintentional ski cut at tower 11 on slushmans lift go 16 inches deep and ran down past tower 3 on lift line today. We had 8 inches from sat/sun and another 8 during the day today."


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Lionhead Range
Lionhead Ridge
Natural and snowmobile triggered wet slabs near Lionhead
Incident details include images
Lionhead Ridge
WS-N-R2-D2
Coordinates: 44.7145, -111.3180
Caught: 0 ; Buried: 0

Skiers in the Lionhead area saw 3 fresh wet slab avalanches on 4/9/2020. One appears to have been triggered by a snowmobile, one by a falling cornice, and the third may have been triggered a wet loose avalanche from above or water running off rocks near the crown. 


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Cooke City
Republic Creek
Natural small point release hit skier
Incident details include images
Republic Creek
L-N-R1-D1-S
Elevation: 9,000
Aspect: SE
Coordinates: 44.9855, -109.9410
Caught: 0 ; Buried: 0

From obs. 4/6/20: "I got tagged by a small point release today. Skinning up the Republic Mountain ridgeline I had stopped to pull skins because it was apparent from hand-pit that the new snow was not bonding well with the old snow interface. I was looking down slope so didn’t actually see the release, but think it was a natural point release that I just happened to be standing in the way of, at least I didn’t feel any collapse so it didn’t seem like I had remotely triggered it.  

Restricted to new snow ~ 6” deep and ran for about 80 vertical feet. Point release in rock band at  ~8,980 to toe at where I was standing at 8,900’ on ESE aspect on ~35° slope ( 45.004, -109.942).

Wx: Overcast, warm (35°+), calm, snowing heavy at time (0.6 SWE at Fisher Creek SNOTEL in 10 hr.)."


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Bridger Range
Bridger Bowl
Multiple skier triggered slides in Bridgers
Incident details include images
Bridger Bowl
SS-AS-R1-D1.5
Coordinates: 45.8156, -110.9230
Caught: 0 ; Buried: 0

Skiers triggered slides in the new snow on Saddle Peak, near Peter's point (just north of Bridger Bowl) and on a north aspect just north of Bradley's meadow. 4/2/2020

Description of Saddle Peak Avalanche:

1-2' deep storm slab released on the Main Face of North Saddle about 100' from the ridge. The skier triggered the slide just uphill of the first cliff band. The avalanche propagated 200' wide and ran over the cliffs to the bottom of Going Home Chute. The skier then climbed out and descended a different route.


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Bridger Range
Bridger Bowl
Skier caught in large sluff at Bridger Bowl
Bridger Bowl
L-ASu-R2-D2-I
Elevation: 9,000
Aspect: E
Coordinates: 45.8156, -110.9230
Caught: 1 ; Buried: 0

An email with some edits:

This morning I skinned up to the ridge alone and went south. I made a turn into some trees and triggered a small sluff below me. I wasn’t comfortable with the amount of snow I moved, so I sidestepped up to the ridge and went back north to the Nose. I dropped into the Nose and made my way to the chute Bombs Away. I skied through Bombs Away and made a few turns in the large apron below the chute before a large sluff I triggered above caught up to me. I stayed on my feet and went through some tight trees, ripping a couple of straps off my backpack, and then I got knocked onto my back. As the slide began to slow, I popped up quickly and managed to ski away. My familiarity with Bridger when it is patrolled influenced my poor decision making, as well as a false sense of being comfortable in dangerous terrain. I am extremely lucky and grateful that it wasn’t worse. I hope others try to avoid similar, poor decision making in this strange post-season at Bridger Bowl.

Another observation from 10 am:
15" crown N facing Knob Job 1. Going on interface between Monday/ Tuesday snow. Thin line of NSF maybe. Crossing Boundary Chute that had mostly cleaned itself out on the upper section, pushed on it on the N facing side and got 2 good whoompfs.


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Northern Madison
Buck Ridge
Snowmobile triggered on Buck Ridge
Incident details include images
Buck Ridge
SS-AMu-R2-D2-I
Elevation: 9,300
Aspect: N
Coordinates: 44.1744, -111.3820
Caught: 0 ; Buried: 0

From obs (3/29/20): "This 44* slope failed 12” under the surface of the snow on a hard crust as we descended to help another stuck rider in a tree. Another layer exists 2” below the failed layer which persisted to follow me down the hill rupturing as fault lines as I continued rapidly down the hill after extracting the stuck rider. While the remaining slope only fractured without chasing me down the hill... "Photo: TJ Krob

On 3/30 forecasters saw two other different slides that broke a foot deep on surface hoar (photo).


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Northern Madison
Beehive Peak
Many natural and skier triggered wind slabs in N. Madison
Incident details include images
Beehive Peak
SS-R2-D2
Coordinates: 45.3539, -111.4050
Caught: 0 ; Buried: 0

Many natural and skier triggered avalanches were reported on wind loaded slopes in the Northern Madison Range on 3/26/2020.

Dudley Creek: "Was up Dudley creek today. Northern madison. Saw 2 step down avalanches on ne aspect high elevation... One ... seemed cornice triggered within 12 hrs of our tour this morning (3/26). The 2nd avalanche is in the lower photo and was probably skier trigger intentional.... It looks like they triggered a fresh wind slab under ridge, maybe ski cut, which stepped down into some older layers"

Beehive & Middle Basins:

-Two natural wind slabs observed on west facing slopes near the ridgeline in Beehive.

-4 skier triggered slides in the new snow on wind affected slopes in Beehive and Middle (observed/triggered by multiple parties)


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Bridger Range
The Ramp
Skier triggered avalanche near Bridger Bowl
Incident details include images
The Ramp
SS-AS-R1-D1.5
Coordinates: 45.8288, -110.9310
Caught: 1 ; Buried: 0

A skier triggered an avalanche on a windloaded slope just north of Bridger Bowl on 3/26/2020. The skier lost their ski in the slide


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Cooke City
Goose Creek
Skier triggered wind slab near Cooke
Incident details include images
Goose Creek
SS-ASc-R2-D1.5-O
Coordinates: 45.0931, -109.9510
Caught: 0 ; Buried: 0

Skier triggered avalanche in Goose Creek.

From obs: "Wind Loaded slope. 2ft Crown. 100ft wide. firm, crusty bed surface. The avalanche was released by a ski cut."


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Northern Gallatin
Hyalite - main fork
Skier triggered slide in Twin Falls Basin
Incident details include images
Hyalite - main fork
SS-ASu-R2-D2
Elevation: 9,000
Aspect: N
Coordinates: 45.4174, -110.9890
Caught: 0 ; Buried: 0

From obs: Small D2 avalanche triggered while assessing the slope on a due-north facing aspect on a roughly 35-40 deg. slope at ~9000 ft. near Arden Lake in the Twin Falls drainage off the Main Fork of Hyalite. ....  Had about a 2 ft deep, 30 ft-long crown. The bed surface was not clearly a sun-crust and was of low quality and remained relatively soft to ski on after the slide. There were crystals above that may be classified as facets, maybe 1mm dia. It seemed to have gone on a compacted layer that the 18" of fresh had weighted."


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Northern Madison
Wilson Peak
Skier triggered wind slab on Wilson Peak
Incident details include images
Wilson Peak
SS-ASu-R2-D1.5-I
Elevation: 10,100
Aspect: N
Coordinates: 45.3270, -111.3250
Caught: 0 ; Buried: 0

From IG post with #gnfacobs: "I triggered a small windslab, mid slope on the north face of Wilson. It was a a pretty stubborn slab that broke above me. Cross loaded from lookers right. 6-8” deep." Photo: B Gill


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Out of Advisory Area
Emigrant Peak
Skier triggered cornice and deep slab on Emigrant Peak
Incident details include images
Emigrant Peak
HS-ACu-R4-D3-G
Aspect: N
Coordinates: 45.2630, -110.7070
Caught: 0 ; Buried: 0

Skiers on Emigrant Peak (outside advisory area) triggered a large cornice from the ridgeline. It broke 75' away from them and triggered a large avalanche when it hit the slope below. The avalanche broke 3-9' deep on weak snow near the ground. The avalanche was 150' wide and ran ~1000'. No one was caught.


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Out of Advisory Area
Knowles Peak
Skier triggered avalanche to ground on Knowles Peak
Incident details include images
Knowles Peak
HS-ASu-R3-D3-O
Aspect: NW
Coordinates: 45.3048, -110.5430
Caught: 1 ; Buried: 0

Skier triggered avalanche on Knowles Peak in the Absaroka Range (outside of advisory area). Avalanche was triggered by 3rd skier on 3/20/2020.

From obs: "I need to report a pretty sizable avalanche that my group triggered today in the Absorokas up the East Fork of Mill Creek on a Northwest facing slope. I believe it was approximately a D3 in scale, the crown was 2-4 feet and about 600 ft wide. It ran to the ground in the start zone and carried debris about 2000ft vertical feet. The debris ran 200ft shy of the the East Fork Rd. It was triggered by the third of three skiers. The skier that triggered the slide took a slightly steeper (approx 34 degrees) line than the other two skiers. The crown started at a convexity in a shallower spot in the snow. We skied this slope last weekend and did a stability test and got a low energy ECT 22. We operated under the assumption that despite some new snow loading the snowpack was generally increasing in stability. We did a hasty pit to see how the new snow was bonding to the old snow surface and it appeared to be bonding well. Solar loading was a concern however this aspect seemed cold and there were no signs of rollers. We really thought this was a good to go situation. The third skier who triggered and was caught lost a ski but was able to ski out of the slide. The two skiers below traversed out of the slide path and kept eyes on the caught third skier. Skiers maintained visual contact at all times. We regrouped and amazingly found the lost ski in the debris pile. It was a scary moment to say the least. Thankfully we are all fine."


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Northern Madison
Dudley Creek
Wet, loose avalanches, Dudley Creek
Incident details include images
Dudley Creek
WL-ASu-R1-D1
Aspect: E
Coordinates: 45.3145, -111.2950
Caught: 0 ; Buried: 0

Two skier triggered wet, loose avalanches. One was intentional and the other was unintentional (skier "went for a small ride on that one"). Both classified as R1/D1 size.  


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Cooke City
Lulu Pass
Snowmobiler triggred slide near Lulu Pass, Cooke City
Incident details include images
Lulu Pass
AMu-I
Coordinates: 45.0709, -109.9580
Caught: 0 ; Buried: 0

Doug talked on the phone with a snowmobiler who triggered a slide outside Cooke City today (3/15/2020). The details:

  • It occurred somewhere between Round Lake and Lulu Pass, likely nearer to Lulu.
  • It was snowing hard most of the day and they had poor visibility.
  • The slide was triggered by 1 sledder. He was not caught.
  • The avalanche broke 1 foot deep and 100 feet wide. It was believed to be new snow, but not wind-loaded.

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Bridger Range
Many natural and skier triggered wind slabs in Bridgers
Incident details include images
SS-AS
Aspect: E
Coordinates: 45.7701, -110.9400
Caught: 0 ; Buried: 0

Observations from Bridger Ski Patrol:

"At 10:30 am natural avalanches were reported Between the Peaks of Saddle, in Argentina Bowl, and on Bridger Peak.  At 11am a solo skier trigger an avalanche on the north peak of Saddle with a cornice drop.  Shortly after, skier triggered avalanches were reported to the north, in Peter's Point, and Barny and Gibbs."

From a skier:

"Really touchy windslab formation throughout the day. 6-12 in slabs running on freeze crust."


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Northern Gallatin
Swan Creek
Snowcat triggered avalanche in Swan Creek
Incident details include images
Incident details contain video
Swan Creek
SS-AKu-R3-D3-O
Elevation: 7,800
Aspect: W
Coordinates: 45.3761, -111.0940
Caught: 1 ; Buried: 0

GNFAC investigation: We went and looked at the avalanche that partially buried a groomer without injury to the driver at 8:15 p.m. the night before (2/27). The slide broke on facets at the ground and was 2-3' deep, 100' wide, and ran 600' slope distance. It put 8' of debris on the road cut. The slope was west facing at 7,500' and averaged 38 degree steep in the starting zone. Weak snow at the ground is found throughout our advisory area.

The groomer triggered the avalanche when he was clearing a wind drift from the road. The groomer is badly damaged.

Crown: N45.38528, W111.06487, 7802 feet

Toe of debris: N45.38554, W111.06693, 7482 feet

Alpha Angle: 30 degrees

Billings Gazette Article HERE.


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Cooke City
COOKE CITY
Small natural and snowmobile triggered windslabs near Cooke City
Incident details include images
COOKE CITY
SS-AM-R1-D1
Coordinates: 45.0202, -109.9380
Caught: 0 ; Buried: 0

Observed two small natural wind slab avalanches on the morning of 2/25 near Daisy Pass.

Then saw four small snowmobile triggered slides on windloaded slopes near Goose Lake that were triggered today. These slides broke 1-2' deep on small slopes. 


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Cooke City
Scotch Bonnet
Snowmobile triggered on Scotch Bonnet, Cooke City
Incident details include images
Scotch Bonnet
HS-AM-R1-D2-O
Elevation: 10,000
Aspect: SW
Coordinates: 45.0706, -109.9520
Caught: 0 ; Buried: 0

"Seemed stability was getting better, but did see this minor slide that pulled out on Scotch Bonnet Mountain. Evidently triggered by a snowmobile sometime mid-day Saturday."


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Bridger Range
Texas Meadow
Skier triggered thin slab in Bridgers
Incident details include images
Texas Meadow
SS-AS-R1-D1
Coordinates: 45.8406, -110.9330
Caught: 1 ; Buried: 0; Killed: 0

From email on 2/20/2020: "I found some localized instabilities, including some wind whales on the ridge north of Bradley’s... The slide in the photo probably happened naturally this late morning, with a trigger of sun-heated snow from the cliffs above (just west of Texas Hill). It ran approximately 100 meters.

From e-mail on 2/21/2020" "I was a few hundred feet north of it when it released. It was skier-triggered by another party traversing high on that slope. It carried the skier for most of the slide path."


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Cooke City
COOKE CITY
Snowmobiler triggered small avalanche near Goose Lake
Incident details include images
COOKE CITY
SS-AMu-R1-D1.5
Aspect: S
Coordinates: 45.0202, -109.9380
Caught: 0 ; Buried: 0

"A small slide approx 100 ft wide ran about 40 vertical feet. Crown was 3-4 feet deep. Aspect, SE. Trigger unknown however tracks indicate it was likely a snowmobile trigger."


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Northern Madison
Buck Ridge
Sledder triggered on Buck Ridge
Incident details include images
Buck Ridge
AMu-R4-D2.5-O
Elevation: 9,300
Aspect: E
Coordinates: 45.1719, -111.3800
Caught: 0 ; Buried: 0

"Went out on a recon to Buck Ridge today. New the dangers and avoided riding open slopes. I had been riding trees most of the day down low and moved up to about mile marker 10 later in the day. Did a side hill through open trees and stopped on top of this slope. Watched it all propagate and slide below me."


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Southern Madison
Taylor Fork
Snowbiker triggered slide in Taylor's Fork
Incident details include images
Taylor Fork
SS-AMu-R2-D2-G
Coordinates: 45.0607, -111.2720
Caught: 1 ; Buried: 0

Slide in Taylor’s fork crown of about 5-6’ and abou100' wide. Human triggered.


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Northern Madison
Buck Ridge
Snowmobile Triggered Slide in McAtee Basin
Incident details include images
Buck Ridge
SS-AMu-R2-D1.5-O
Coordinates: 45.1834, -111.4400
Caught: 1 ; Buried: 0

From observation: "My riding group came upon a group of three riders from out of state digging out a sled. A single rider had been side hilling a steep slope above a deep creek drainage. This is where the trail leaves Third Yellow mule and drops into McAtee. The slope broke with a single rider high on the slope completely burying the sled. The rider managed to stay on top of the debris. The debris was very deep (~12'-15') as it filled in the drainage below."


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Northern Gallatin
Garnet Mtn.
Remotely triggered avalanches on Garnet Mtn.
Incident details include images
Garnet Mtn.
HS-ASr-R1-D1-O
Elevation: 8,000
Aspect: NW
Coordinates: 45.4240, -111.2050
Caught: 0 ; Buried: 0

Two avalanches simultaneously remotely triggered by skiers on Wednesday, 2/12/2020. 

From email: "NW aspect at 8000 ft on Garnet Mountain. Two slides, one 15 feet across and one 10 feet across, remotely triggered from 15 ft away. Crown was about four feet deep, triggered on the facets. Didn't travel more than 30 vertical feet.  One slide triggered in dense trees, and both slides traveled into densely treed areas. The snowpack was relatively shallow in the area where slide was triggered. Signs of instability were noted (Back on low angle terrain, after triggering the above slide), Cracks that propagated out 10+feet and were very deep and whomphing."


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Northern Madison
Deer Creek
Slides triggered in Deer Creek, N. Madison
Incident details include images
Deer Creek
SS-ARr-R1-D1-S
Elevation: 6,700
Aspect: NE
Coordinates: 45.2988, -111.2040
Caught: 0 ; Buried: 0

"Today while touring in the Deer Creek drainage in the Northern Madisons my partners and I noticed many red flags. Wind was strong from the WSW. We had lots of collapsing and some cracking while touring up. We bailed on our main objective, and while returning to the car we triggered a wind slab remotely from the bottom flats of a gulley. A rider in our group began to descend when we felt and heard a large whumph, followed by a 3-5 second loud rumbling before a wind slab on the ridge above (100 yards away) released (SS-ARr-R1-D1-S, NE aspect @ 6700'). It was about 50' wide and 1-2' deep, but didn't have enough energy to run far down the slope. Touchy stuff!"


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Northern Gallatin
Portal Creek
Snowmobiler triggered avalanches in Portal Ck, N. Gallatin
Incident details include images
Portal Creek
SS-AMu-R2-D1-I
Coordinates: 45.2890, -111.1410
Caught: 0 ; Buried: 0

A snowmobiler found very touchy conditions in Portal Creek. The new snow easily avalanched on road cuts so they went home.


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A child triggered a small avalanche
Incident details include images
SS-AFu-R1-D1
Caught: 0 ; Buried: 0

On private property, this small child triggered a slide and climbed out of the debris, not buried. A very close call! On the heels of this large snowstorm there are possibilities of children getting caught on road cuts or any open hill!


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Northern Madison
McAtee Basin
Snowmobile Triggered Avalanches, McAtee Basin
Incident details include images
McAtee Basin
SS-AMu-R2-D2-O
Elevation: 8,900
Aspect: SW
Coordinates: 45.1771, -111.4350
Caught: 0 ; Buried: 0; Killed: 0

We saw a group of six snowmobilers who said they triggered these slides in McAtee Basin on the left side of the meadow on Saturday, Feb 8. I didn't see tracks up on the hill or sidehill tracks so they may have triggered the slope from the flats below. The debris runs all the way to the bottom of the hill. 


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Bridger Range
Texas Meadow
Skier triggered south face Texas meadow
Incident details include images
Texas Meadow
SS-ASu-R3-D2.5-I
Elevation: 7,500
Aspect: S
Coordinates: 45.8406, -110.9330
Caught: 0 ; Buried: 0
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Northern Gallatin
Hyalite - main fork
Small avalanche triggered under Dribbles Ice Climb in Hyalite
Hyalite - main fork
SS-AFu-R1-D1
Aspect: SW
Coordinates: 45.4472, -110.9620
Caught: 0 ; Buried: 0

"Additionally, on Wedensday my climbing partner and I dug an informal pit because we were concerned with accessing the lower pitches of the dribbles from the point the bootpack ended. We noticed that sugary layer some ways down and went around..when we tried to come up the from the southwest I caused another small slide that was significantly deeper than the one I sent you (2/02); I feel like if it had happened from where people normally cross to climb Dribbles it could have been bad."


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Southern Madison
Skyline Ridge
Snowmobile triggered big slides on Skyline Ridge
Incident details include images
Skyline Ridge
HS-AMu-R3-D2.5-O
Elevation: 10,000
Aspect: SW
Coordinates: 44.9205, -111.2300
Caught: 0 ; Buried: 0

From Obs. form: "[Slope] Was marked up previously. We parked out near the bottom and a few guys not in our group start climbing. So we watch them climb. It breaks out. Guy ditches the sled and manages to stay up top. Sled goes down with the slide. Then the snow breaks in 2 other spots creating more slides."

From riders involved: "Yesterday we were the ones in the big sky avalanche. There was no markings on the spot we were climbing. Further down the mountains there were climbs at the same angles of this slope. Thankfully the rider was above the slide when it started and managed to stay on top. Rider walked down the debris and we found the sled lower down in the trees. No injuries."


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Cooke City
Crown Butte
Snowmobile triggered wind slab Crown Butte
Crown Butte
SS-AMu-R3-D1-S
Elevation: 10,000
Aspect: SE
Coordinates: 45.0525, -109.9620
Caught: 0 ; Buried: 0

R3/D1 wind slab off of the SE side of Crown Butte. Observed from Henderson, and there were numerous sled tracks in the debris/runout.


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Lionhead Range
Lionhead Ridge
Snowmobile Triggered Avalanche Lionhead
Incident details include images
Lionhead Ridge
HS-AM-R2-D2-G
Elevation: 8,800
Aspect: N
Coordinates: 44.7336, -111.3290
Caught: 1 ; Buried: 0

From email: "I wanted to make you aware of a snowmobile triggered slide in Lionhead today. Fortunately, I was not injured, was able to stay completely on top, climbed through the majority of the snow wash after seeing it begin to break, and relatively slowly slid down with the last of the moving snow while still on the machine. When I came to a stop I stood up and was completely free of the snow. Our group is trained in avalanche safety, practiced beacon use prior to leaving town in the morning, were wearing avy gear, and were very fortunate that this ended the way it did.  

A clear reminder that this can happen to any of us and to be careful out there."


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Northern Madison
McAtee Basin
Snowmobile Triggered Avalanche McAtee Basin
Incident details include images
McAtee Basin
HS-AMu-R2-D2-O
Coordinates: 45.1771, -111.4350
Caught: 0 ; Buried: 0

From Instagram: "I watched a snowmobiler set this avalanche off today. Very scary in MT right now."


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Centennial Range
Reas Peak
Snowmobile triggered near Reas Peak
Incident details include images
Reas Peak
HS-AMu-R4-D2.5-O
Coordinates: 44.5477, -111.4860
Caught: 0 ; Buried: 0

Snowmobiler triggered avalanche near Reas Peak on Sunday, 1/19/20. he was able to ride through it uphill.


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Bridger Range
Texas Meadow
Skier triggered north of Bridger
Incident details include images
Texas Meadow
HS-ASu-R2-D2-O
Elevation: 8,000
Aspect: SE
Coordinates: 45.8406, -110.9330
Caught: 0 ; Buried: 0

A skier was skinning uphill, breaking trail and triggered this avalanche on 1/19/20. They reported, " released a small pocket near texas meadow. Maybe 50 ft wide, 2 ft crown and ran 150 ft....I was not caught and nobody was buried or injured. I was skinning up at about 1130...I got to where it was steeper and as I reached thinner snow near rocks I felt a whump. I took one more step and the pocket released."


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Northern Madison
Cedar Mtn.
Snowmobile triggered on Cedar
Incident details include images
Cedar Mtn.
HS-R3-D2.5-O
Elevation: 10,000
Aspect: NE
Coordinates: 45.2263, -111.4960
Caught: 0 ; Buried: 0

I was on the west side of Pioneer Mtn digging a pit for YC Ski Patrol. I heard a few groups of snowmobiles cruising around the foothills of cedar. I turned and saw two snowmobilers cresting the ridge above the slide pictured as the debris was settling down. The sledders enjoyed the view for a few minutes before turning back the way they came and stumbled upon the slide they had unknowingly triggered. They skirted around the side of the crown and stopped for a few minutes. Based on the height of the rider off his sled, I would estimate the crown to be roughly 10’ at its max height. NE aspect below Cedar


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Northern Gallatin
Flanders Creek
Skiers triggered 2 large slides Flanders Mtn.
Incident details include images
Incident details contain video
Flanders Creek
HS-ASu-R3-D2-O
Elevation: 9,800
Aspect: NE
Coordinates: 45.4351, -110.9440
Caught: 0 ; Buried: 0

From Obs: "... Our party of two was ascending southwest on a rib with the intention of reaching the ridgeline. At 9800', the upper member of our party triggered a D2.5 with an approximately 100' crown immediately to our south. Crown height appeared 2-3' and the slide traveled approximately a distance of 2,000' and 500 vertical feet down mountain. Within a few seconds, we remote triggered to the north a D3 with an approximately 200' crown. Crown height appeared up to 7' at highest point and slide traveled approximately 300 vertical feet down mountain. The remote triggered slide started approximately 15-20 feet to the north of the location of the lower member of our party, who was approximately 30 vertical feet below the upper member of our party. After the slide the upper member of our party noticed a shooting crack at his elevation. Two skiers and one dog were ascending below us. They observed the avalanche and later mentioned that they were approximately 150 feet in distance from the toe of the remote triggered slide, which completely covered their skintrack. Nobody caught or buried."

From group that was below: "Finished a snow pit at 45.434589, -110.940957. Results were ECT-X, Aspect: 110 deg, Angle: 27 degrees, Depth: 90 cm, Weak layer was above melt/freeze at 60 cm, fist hardness above 62 - 67 cm. Then fairly cohesive newer snow 70 - 90 cm. Weak layer did not budge, even when levered with the shovel.

Knowing there was one party of two ahead of us, we continued to 45.434716, -110.94124 when they triggered slide above. It ran through one of the avalanche paths behind us, that we had crossed. We whooped to see if someone was the trigger and if they were ok, they yelled back all was ok. Our mistake was assuming the party ahead was taking, what we consider to be, the standard route up Flanders, not the subtle ridge that we figured was loaded by the month of west/sw winds We were wrong and were traveling below them but still were traveling in the older trees and not in slide paths, yet another example of why you follow protocol. Anyways I took a bunch of pics. Pin on map is about where they triggered it."


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Southern Madison
Taylor Fork
Snowmobile triggered in Taylor Fork
Incident details include images
Taylor Fork
SS-AMu-R2-D2-O
Elevation: 9,200
Aspect: NE
Coordinates: 45.0607, -111.2720
Caught: 0 ; Buried: 0

From obs: "2nd hand observation arrived at site about 5 minutes after slide. Triggered by sidehilling snowmobiler but was not caught up in it. looked approximately 50 ft wide 150 ft vertical. Did not appeared to be very deep."


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Northern Gallatin
Wheeler Mountain
Skier triggered small slide Mount Wheeler
Wheeler Mountain
SS-AS-R1-D1.5-O
Coordinates: 45.5097, -111.0820
Caught: 0 ; Buried: 0

From obs: "Skied into to a pillow of snow. I think it started as just sluff but then broke off an avalanche. It was not wide but the crown is estimated at 2 feet. It was not moving fast and I just dug into the bed surface and slowly moved out of it. I was the second skier. The first skiers track did not go as deep as mine. failed on weak facets at the base of a steep roll over."


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Cooke City
Henderson Mountain
Two big snowmobile triggered on Henderson Mtn., Cooke City
Incident details include images
Incident details contain video
Henderson Mountain
HS-AMu-R4-D2.5-O
Elevation: 10,000
Coordinates: 45.0448, -109.9330
Caught: 0 ; Buried: 0

Two big avalanches were triggered on Henderson Mountain near Cooke City on 1/16/20. One was huge. The other was still big enough to bury or kill somebody. Nobody was reported caught or injured. Report and photos from a third party that did not witness the slides occur, but were in the area earlier this day and saw the slopes had not slid.

From forecaster site visit: "We parked near the bottom of the debris on the Henderson slide and climbed to the crown. Knife hard wind slab; failed on facets at the ground that were 1F+ hardness (2-4mm). The crown was 5 meters deep (measured) and tapered to 16". There are lots of rocky and thin zones on this slope that were likely the trigger point. Vertical distance was 600', 1000 feet wide, debris was 10' deep."


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Bridger Range
Argentina Bowl
Skier triggered avalanche near Saddle Peak
Incident details include images
Argentina Bowl
SS-ASu-R3-D2.5-O
Elevation: 8,600
Aspect: E
Coordinates: 45.7869, -110.9350
Caught: 1 ; Buried: 0

Skier triggered avalanche in Argentina Bowl on Saddle Peak. Observed from the highway. Occurred during the day on Wednesday, 1/15/2020.

From e-mail: "Skiers triggered two separate slides on south Saddle this afternoon. we witnessed the smaller slide to the lookers right of the big slide, the bigger one happened later apparently... The first smaller slide was caused by a ski cut near the trees, fracture was about 2 feet, soft slab that seemed to run on a thin sun crust. below the sun crust was also very weak and sugary. Not sure when the second skier went farther out and triggered the whole bowl, but they got lucky!!"


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Southern Madison
Taylor Fork
Snowmobile Triggered Avalanche in Taylor Fork
Incident details include images
Taylor Fork
SS-AMu-R1-D1-G
Aspect: E
Coordinates: 45.0607, -111.2720
Caught: 0 ; Buried: 0

A small but relatively deep avalanche triggered by a snowmobiler on Tuesday, 1/14/2020. 30 ft wide. Ran 20 vertical feet. This avalanche broke to 2-3 ft deep, to the ground. This is the second time this year this slope has slide, it also avalanched in mid-December.


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Bridger Range
Saddle Peak
Skier triggered slide on Saddle Pk
Saddle Peak
SS-ASu-R1-D2-I
Elevation: 8,900
Aspect: NE
Coordinates: 45.7943, -110.9360
Caught: 0 ; Buried: 0

A skier in the Slushman's lift line at 12:30 watched a skier trigger a soft slab above the first cliffs on the face of Saddle. They skied out and got lucky. It was 150' wide propagated towards the skyline ridge.


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Cooke City
Daisy Pass
Snowmobile Triggered Slide on Chimney Rock
Incident details include images
Daisy Pass
SS-AM-R2-D2
Aspect: SW
Coordinates: 45.0497, -109.9640
Caught: 0 ; Buried: 0

Snowmobile triggered avalanche on the WSW face of Chimney Rock near Daisy Pass. Likely triggered morning of 1/10/2020.


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Cooke City
Town Hill
Skier triggered avalanche on Town Hill, Cooke City
Incident details include images
Town Hill
SS-ASc-R0-D1
Elevation: 8,200
Aspect: S
Coordinates: 45.0256, -109.9370
Caught: 0 ; Buried: 0

Skier triggered slide on Town Hill.  A southerly aspect at 8200'.  It was triggered with a ski cut, and no one was caught.  Specs: about 2' deep, 50' wide, and it ran about 75' vertical.


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Northern Madison
Yellow Mountain
Skier triggered avalanche in N. Madison
Yellow Mountain
SS-ASu
Elevation: 9,200
Aspect: NE
Coordinates: 45.2995, -111.3200
Caught: 0 ; Buried: 0

From an email:

9200 ft - NE Aspect CT13-Q2 •Wind-loading of leeward N & E facing slopes •10-20 mph winds

My partner and I skied the apex of the ridge to avoid avalanche terrain, he triggered a soft slab, 1.5 ft deep, off the top of the ridge, crown 100ft wide, ran 300 ft down slope. Collapsing observed on the lower tree portions of the exit out Trail Ck.


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Northern Madison
Middle Basin
Middle Basin Cornice Fall
Incident details include images
Incident details contain video
Middle Basin
C-AOu-R2-D2-I
Elevation: 9,200
Aspect: SE
Coordinates: 45.3237, -111.3810
Caught: 0 ; Buried: 0

Large cornice collapse in Middle Basin. The cornice broke 10' back from the edge, 6-7' deep, and ran 800-1000' vertical. The collapse was triggered by a dog in another party.

The crown depth in the cornice was 6-7', but the snow rode up onto the interface and gouged 24" of snow out. 


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Northern Madison
Buck Ridge
Three snowmobilers caught in very large slide on Buck Ridge
Incident details include images
Incident details contain video
Buck Ridge
HS-AMu-R4-D3-G
Elevation: 9,300
Aspect: NE
Coordinates: 45.1719, -111.3800
Caught: 2 ; Buried: 2; Killed: 0

From one of the riders caught in the slide, "The 3 persons involved were traveling across the slope about 20-30 yards up from the tree line parallel to the ridge line in the slide area when it broke, not high marking and not traveling uphill. One rider did increase his elevation while traveling across the slope but was never more than 1/4 of the way up when the slide was triggered."


@carter.olson, "I witnessed three snowmobilers trigger and get caught in an avalanche at second Yellowmule (Buck Ridge) at 12:40PM today. The lead snowmobiler triggered the avalanche while descending from his high mark with the other two snowmobilers below him. The lead snowmobiler was able to run out the avalanche to a degree and made it to the edge of the runout at the bottom. The other two snowmobilers were pointed uphill when the avalanche was triggered and shot into the trees when attempting to outrun the avalanche. The female was buried to her torso and the male was buried to his waist. Both sleds were buried about three feet under the debris. The Avalanche propagated about 1500ft wide. Luckily everyone involved was not harmed, just a broken a arm on one of the buried sleds.
Luckily I was able to jump into action, yelling “Avalanche, Avalanche, Avalanche” grabbing everyone in my group’s attention. Then I told everyone to get their beacons out and put them to search and get to where we last saw the snowmobilers. On our way to the last point of sight of the snowmobilers, they all screamed out they were ok."


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Northern Gallatin
Flanders Creek
Ice climber hit by loose snow avalanche on Killer Pillar, Hyalite
Flanders Creek
L-N
Aspect: NE
Coordinates: 45.4402, -110.9310
Caught: 0 ; Buried: 0

From an email:

"Got hit by a pretty decent loose snow avalanche from above while topping out on Killer Piller up Flanders. Had a decent stance so I was able to hold on. Also observed more than a few coming down gullies on the other side of the drainage. It was lightly snowing all day and dead calm in the drainage, so presumably winds were cranking on the ridgetop."


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Cooke City
Henderson Mountain
Two large, deep avalanches on Mt. Henderson near Cooke
Incident details include images
Incident details contain video
Henderson Mountain
HS-AMu-R2-D2-O
Elevation: 10,000
Aspect: NE
Coordinates: 45.0524, -109.9450
Caught: 0 ; Buried: 0

Skiers reported: "Two new [trigger unknown] avalanches on the east side of Henderson today. The first photo is from this morning (12/27/19) around 11:00. The second one appears to be much deeper and I didn't notice it until I rode back by around 2:30, so it might have occurred while I was out skiing or I just missed it this morning."

From Dave and Doug's investigation on 29 Dec:

1. The lookers left avalanche was the deepest at 6' deep of Hard Slab. Estimated 150' wide and 300' vertical. It broke on facets near the ground.

2. The avalanche to the right was 3' deep and also broke on facets near the ground. It too was heavily wind-loaded. Estimated 250' wide and 300' vertical.


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Cooke City
Daisy Pass
Snowmobiler triggered avalanche near Daisy Pass, Cooke City
Incident details include images
Daisy Pass
HS-AMu-R2-D2-O
Elevation: 10,000
Aspect: NW
Coordinates: 45.0497, -109.9640
Caught: 0 ; Buried: 0

A snowmobiler triggered this avalanche. He was not caught. This slope is below Chimney Rock next to Daisy Pass. It is a heavily wind-loaded slope and failed on facets at the ground.


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Cooke City
Crown Butte
Three snowmobile triggered avalanches near Cooke City
Incident details include images
Crown Butte
SS-AMu-R1-D2-O
Aspect: SE
Coordinates: 45.0525, -109.9620
Caught: 0 ; Buried: 0

From email: "Saw 3 different slides today, all had sled tracks near or into them, and were breaking from rocks... The other slides were smaller, had broken from rocks at the top of ridges. Also saw some cracking mid slope, on this same aspect, a ridge over down left of this photo."

Photo is of avalanche on SE aspect of Crown Butte.
 


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Cooke City
Mt. Abundance
Snowmobile triggered/caught on Mt. Abundance near Cooke
Incident details include images
Incident details contain video
Mt. Abundance
HS-AMu-R3-D2.5-O
Elevation: 9,200
Aspect: E
Coordinates: 45.0642, -110.0110
Caught: 0 ; Buried: 0

From IG post: "Pictures don’t do this monster avalanche justice. We helped the kid recover his sled, which was buried between 4and 10 feet. luckily it wasn’t him and no one was hurt." @mackleymtvet

E-mail from uninvolved group: "Incident occurred on an East aspect of the far south shoulder of Abundance.  Did not witness incident or know the party involved, but arrived shortly after it occurred. Involved party was still on scene. Rider was approaching blind roll over from the top when slide was triggered at the visible crown. Rider attempted to bail, but both the individual and machine were carried over and through the rocks and strainers below. Rider and machine were deposited in the debris pile as seen in pictures. Rider was unharmed. Machine was pretty well trashed. Information based on first person observation and rider testimony."


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Cooke City
Daisy Pass
Natural and human triggered slides in Cooke City
Incident details include images
Daisy Pass
Coordinates: 45.0532, -109.9610
Caught: 1 ; Buried: 0

Bill Whittle of Cooke City SAR reported that one sledder triggered a slide in a terrain trap to the northwest of Lulu Pass (45.06703, -109.97180). It caught him, but he was not buried. It only buried the tail of his sled. He hit his "SPOT" rescue beacon because he was stuck.

Separately, a little while later, a rider on a rental sled was unable to ascend Daisy Pass to return to town. As he was walking up the pass and others were retrieving his sled, a 2 foot deep (est.) natural slide released on the northeast aspect of Crown Butte that missed them.

Since the storm began 26 hours ago, 1.4" of snow water equivalent fell which is estimated to be 2 feet of snow.

Winds were W-SW averaging 10-20 mph with gusts reaching 44 mph (Lulu Pass weather station)


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Out of Advisory Area
Ice climber triggered and caught in avalanche in Upper Mill Creek, Absarokas
HS-AFu-R3-D2-I
Elevation: 9,000
Aspect: NW
Coordinates: 45.2776, -110.5030
Caught: 1 ; Buried: 0

Outside advisory area, but seemed relevant to report a climber triggered avalanche today (12/11/2019) at around 9000 ft, on a 35 degree slope on a NW aspect. Solid size 2, triggered roughly 15m below the crown (depth 20-40 cm, width 15m) Failed on a density change below a fresh windslab, ran around 100m and deposited 1m of debris towards the bottom of the runout. HS-AF-D2/R3-I. No injuries.


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Bridger Range
Bridger Bowl
Several small skier triggered/natural slides at Bridger
Bridger Bowl
SS-AS-R1-D1
Coordinates: 45.8156, -110.9230
Caught: 0 ; Buried: 0

Several reports of small skier triggered slides at Bridger Bowl (10/29).

From instagram:

"I kicked off a small 6 inch slab on a rollover skiing down east of PK."

"Skied ptarmigan this morning, kicked off a decent sized slab rolling over deer park road cross from avy gulch."

"I got a 2 foot wind slab to crack on a test slope. There was lots of evidence of heavy wind affect. Saw a 5 inch by 20 foot slide in sluice box gully (skier triggered)."

From an email: "Skinned part way up Slushmans yesterday, saw that a chunk of cornice had fallen over the south side of the football field and took a medium-sized slab with it. The debris didn’t make it over the cliffs, but I did see debris further to the south."


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