Avalanche Activity

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


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Northern Gallatin
Maid of the Mist
Natural cornice triggered in Maid of the Mist basin
Incident details include images
Maid of the Mist
SS-NC-R1-D2-I
Elevation: 10,000
Aspect: E
Coordinates: 45.4111, -110.9880
Caught: 0 ; Buried: 0

From obs. (3/29/20): "Significant wind started building mid morning, forming even bigger cornices and wind loading many slopes. Noticed this slide on an East/Northeast aspect at the back of the bowl above Maid of the Mist creek, possibly triggered by cornice fall but unknown. Happened between 9:45am and 11:30am today, as at 9:30am it was not there, and when we returned to the spot around 11:30am the slide was visible." Photo: CP


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Bridger Range
Fairy Lake
Cornice Fall near Fairy Lake
Incident details include images
Fairy Lake
C-N-R2-D1.5
Elevation: 9,000
Aspect: E
Coordinates: 45.9043, -110.9580
Caught: 0 ; Buried: 0

Skiers near Fairy Lake reported a cornice collapse in October Bowl.


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Bridger Range
Ross Peak
Collapse near Ross Peak
Ross Peak
Coordinates: 45.8591, -110.9550
Caught: 0 ; Buried: 0

After getting unstable snowpack test results, skiers on 3/27/2020 got a collapse on facets over a crust buried about a foot deep, near Ross Peak in the Bridger Range.


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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 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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Southern Madison
Quake Lake
Natural windslabs near Quake Lake
Quake Lake
SS
Coordinates: 44.8524, -111.3920
Caught: 0 ; Buried: 0

Natural avalanches near Quake Lake, observed on 3/26/2020.

From email: "I observed several small natural slides originating on recently-loaded, corniced ridgelines. These all ran substantial distances, but did not pick up much snow or step down from the new snow."


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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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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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Northern Gallatin
Divide Peak
Natural and skier triggered slides in Hyalite
Incident details include images
Divide Peak
SS
Coordinates: 45.4029, -110.9760
Caught: 0 ; Buried: 0

From obs: "Later in the day we ran across what we assume to be a remotely triggered avalanche from another party in the area. There were two sets of tracks on the adjacent slope with cracks visible on the slope. The avalanche occurred on a 40* east aspect at 9250' and failed on the MFcr/FC dn 35cm. .... Skiing out the trail with better light than in the morning, we saw a number of similar avalanches confined to east aspects on steep 40*+ rolls and presumably failing on the persistent grains above the crust."


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Bridger Range
The Throne
Natural avalanches in new snow in Bridgers
Incident details include images
The Throne
SS-N
Coordinates: 45.8822, -110.9520
Caught: 0 ; Buried: 0

From obs: "We toured up in the Throne area today. Moderate winds were blowing snow at mid elevations and ridgetops. We found dry boot top powder on East facing slopes, the snow skied upside down. We observed loose and slab avalanches on many aspects up high and at mid elevations, all looked like new snow avalanches that happened yesterday. I’ve attached a photo of an east facing slope near the Throne."  Photo: S. Jonas


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Cooke City
COOKE CITY
Natural avalanche in Cooke
Incident details include images
COOKE CITY
SS-R2-D1.5
Coordinates: 45.0202, -109.9380
Caught: 0 ; Buried: 0

From email on 3/27/2020 : "natural slab avalanche I observed today near Cooke City.  An easterly aspect around 9,400'.  I'd estimate the crown to be 2-3' deep and about 100' wide.  Looks like it was triggered by a cornice fall (2-3 days ago?)."


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Bridger Range
Bridger Bowl
Natural avalanches in the new snow, Bridger Range
Incident details include images
Bridger Bowl
SS-N-R1-D1-I
Coordinates: 45.8156, -110.9230
Caught: 0 ; Buried: 0

1. Saw some really cool small avalanches today at Bridger. There was an obvious cycle last night on a density change, it wasn't sliding on the crust. The instability had decreased by 10 am and we couldn't get anything to move. Really cool to see such thin soft slabs propagating up to 50 ft. Good piles of debris under steep chutes.

2. Soft slabs were reactive on rocky south easterly aspects where sun crusts had formed.


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Northern Gallatin
Mt Blackmore
Human Triggered Soft Slab Avalanches - Mt Blackmore
Incident details include images
Mt Blackmore
SS-ASc-R1-D1-S
Elevation: 10,000
Aspect: N
Coordinates: 45.4444, -111.0040
Caught: 0 ; Buried: 0

Snowfall throughout the afternoon fluctuated between S1 - S5 (during brief squalls). The winds started out moderate and from the west but calmed by the last lap ~5 pm. The new snow (from last night/this morning) was fairly well bonded to the sun/melt-freeze crust below, but the storm came in subtly upside down. Today’s snowfall (accumulating ~3” while skiing between 1-530) was light. Right along the ridgeline, we triggered 4 predictable small storm slabs 4~6” deep on the upside-down storm snow from last night/this morning, but surprisingly not on the old crust. They were each 5-10m wide x 5m long and only ran ~5m vertically. 


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Northern Madison
Small soft slabs northern Madison range
Incident details include images
SS-N-R1-D1-O
Aspect: N
Coordinates: 45.3126, -111.3110
Caught: 0 ; Buried: 0

From obs: "Was out today and found buried surface hoar 10-15 cms down. Some previous natural activity on this layer on steeper north aspects with very shallow soft slabs, but mostly dry loose at this point. Not much slab formation since the last ppt event. This could be a problem when more snow and wind in the next few days."


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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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Northern Madison
Yellow Mountain
Wet loose slides near Big Sky
Incident details include images
Yellow Mountain
WL-N-R1-D1.5
Elevation: 9,300
Aspect: S
Coordinates: 45.2995, -111.3200
Caught: 0 ; Buried: 0

From e-mail: "Natural wet slides [on 3/21]... caused us to back off our plan of heading that way and ski a north, shady aspect instead. On a southern aspect at 9000ft at 1:30pm we dug a hasty pit and observed a weak layer about 1m down. The facets were beginning to round." Photo: K. Master


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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-AS-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
Republic Creek
Natural Avalanche Upper Republic Creek
Incident details include images
Republic Creek
SS-NC-R1-D1.5-I
Elevation: 10,000
Aspect: NE
Coordinates: 44.9855, -109.9410
Caught: 0 ; Buried: 0

A small slab avalanche in the upper valley. A northeast aspect around 10,000'.

Also, there appeared to quite a bit more (thin) storm slab activity that occurred up Republic Creek yesterday (both east and west aspects).  I'd hypothesize that most of the slides that ran yesterday, were on the density change within the new snow.


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Bridger Range
Frazier Basin
Intentionally Triggered Wind Slab - Northern Bridgers
Incident details include images
Incident details contain video
Frazier Basin
SS-ASc-R1-D1-I
Elevation: 9,000
Aspect: N
Coordinates: 45.9200, -110.9800
Caught: 0 ; Buried: 0

We intentionally triggered a small wind drift and cornice prior to skiing this north-facing line in Frazier Basin. The slab broke easily with a ski cut and propagated 20' in front of my ski tips. 


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Bridger Range
Fairy Lake
Natural Wet, Loose Avalanches Bridgers
Incident details include images
Incident details contain video
Fairy Lake
WL-N-R1-D1-I
Elevation: 8,000
Aspect: SE
Coordinates: 45.9043, -110.9580
Caught: 0 ; Buried: 0

We observed 7 wet, loose snow avalanches today in the Northern Bridger Range. All avalanches were in the R1, D1-1.5 size range. They would be consequential in the steep, technical terrain where they occurred. 


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Northern Madison
Dudley Creek
Natural Wet Snow Avalanche, Dudley Creek
Incident details include images
Dudley Creek
WS-N-R3-D3
Elevation: 9,000
Aspect: E
Coordinates: 45.3145, -111.2950
Caught: 0 ; Buried: 0

Natural wet snow avalanche on the east face of Dudley, R3/D3 likely occurred Monday, March 16th.  


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Northern Madison
Beehive Peak
Natural avalanche north of Beehive Peak
Incident details include images
Beehive Peak
SS-NC-R2-D2.5-O
Coordinates: 45.3539, -111.4050
Caught: 0 ; Buried: 0

Natural avalanche north of Beehive peak, next to North Twin behind the Fourth of July couloir. Looks to have broken on weak layers near the ground. May have been concern triggered. Observed 3/19/2020. Exact timing of release is unknown. Estimated 3/16/2020.


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Northern Gallatin
Alex Lowe Peak
Natural Cornice break and wet loose in Alex Lowe Basin
Incident details include images
Alex Lowe Peak
WL-NC-R1-D1-I
Coordinates: 45.4253, -111.0120
Caught: 0 ; Buried: 0

From the Blackmore/Elephant saddle I observed what looked to be a less than a day old cornice break which triggered a loose wet slide in front of it. The cornice debris was large, about the size of a VW beetle. Also observed some surface hoar on the north side of the saddle.


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Southern Madison
Hebgen Lake
Ski Cuts - New Snow Avalanches near Hebgen Lake
Hebgen Lake
SS-ASc-R1-D1-I
Coordinates: 44.8381, -111.3430
Caught: 0 ; Buried: 0

The steeps were inclined to move cohesively when ski cut, but no natural movement. Pretty good skiing, but greenhouse clouds warmed up the surface in the afternoon. 


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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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Cooke City
Mt. Zimmer
Natural new snow slab avalanches, Cooke
Incident details include images
Mt. Zimmer
SS-N-R2-D1.5-S
Elevation: 10,000
Coordinates: 45.1170, -109.8930
Caught: 0 ; Buried: 0

From e-mail on 3/15/20: "At around 1230pm today, everything that was steeper than 35 degrees in star Creek simultaneously slid on east, north, south aspects. Soft slab 6-12" in thickness. Prior to that, it had been snowing S5 for three hours"

Another email 3/15/20: " observed a round of natural slab avalanches today, that seemed to run at about noon today on the north aspects of Mt. Republic.  One was a couple hundred feet wide, and looked to happen within the new snow (6"? deep crown), but it stepped down to what appeared to be the new/old snow interface in a couple of spots as well.  Significantly wide propagation and deep debris piles.  The snow on Town Hill was cracking a lot early in the day around your skis, but seemed to settle relatively quickly, 


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Southern Madison
Skier triggered small soft slab, Southern Madisons
SS-AS
Coordinates: 44.9156, -111.3940
Caught: 0 ; Buried: 0

Small skier triggered slide.


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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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Cooke City
Republic Creek
Cornice triggered avalanche in Republic Creek, Cooke
Incident details include images
Republic Creek
C-N-R2-D2.5
Aspect: E
Coordinates: 44.9855, -109.9410
Caught: 0 ; Buried: 0

The GNFAC saw this on Tuesday morning (3/10) from Woody Ridge. Winds were strong and loading slopes.


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Bridger Range
Saddle Peak
Skier triggered avalanches in the new snow on Saddle Peak
Saddle Peak
SS-AS-R2-D2-I
Elevation: 9,000
Aspect: E
Coordinates: 45.7932, -110.9350
Caught: 0 ; Buried: 0

Multiple laps on Saddle today. New snow peeling cleanly on hard crust on ski cuts at steep roll overs. Would run until pitch tapered off. Ran slow but pretty big. Debris was 4-6 feet deep. South Central (upper face) of South Saddle and Face of North Saddle under 2nd rock were the biggest producers.


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Northern Gallatin
Hyalite - main fork
Natural Wet, Loose Avalanches Hyalite
Hyalite - main fork
WL-N-R1-D1-I
Coordinates: 45.4472, -110.9620
Caught: 0 ; Buried: 0

Today in Hyalite there was roughly 5" new snow. It quickly lost cohesion when the sun came out and many size 1 dry and wet loose came off of steep rocky areas. I did not observe anything larger. Yesterday I observed a cornice fall on an E aspect of Mt. Bole around 9500 ft that probably occurred on 3/6. It ran several hundred meters downhill, entrained some surface snow, and appeared to trigger a size 2 slab when it encountered steeper terrain. That being said I was at G1 so I didn't really get a good look at it.


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Northern Gallatin
Mt Blackmore
Natural Dry, Loose Avalanches on Blackmore
Incident details include images
Mt Blackmore
L-N-R1-D1-I
Elevation: 9,800
Aspect: E
Coordinates: 45.4445, -111.0020
Caught: 0 ; Buried: 0

Dry loose avalanches on Blackmore. The snow stayed surprisingly cold and dry throughout the day.


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Northern Madison
Middle Basin
Skier triggered avalanches in the new snow in Middle Basin
Incident details include images
Incident details contain video
Middle Basin
SS-ASc-R1-D1.5-I
Elevation: 9,300
Aspect: W
Coordinates: 45.3384, -111.3770
Caught: 0 ; Buried: 0

My partner and I toured over from Beehive into Middle Basin today (saw your car in the parking lot) and finding relatively dry snow in the shade headed for a west facing chute on the ridge that divides Middle and Bear Basins. The chutes walls kept it mostly shaded all morning and it was mostly cloudy as we started skinning up its apron. We had no cracking or signs of cohesion as we approached and a relatively easy boot pack up the chute. A couple of hand pits on the way up showed little cohesion within the top layer and a fairly dry snowpack underneath. We made plans for sluff management with protected spots to let it pass on both sides of the chute. While stomping out a platform we were able to kick off boot sized chunks of snow with no reaction My partner dropped first and his first turn kicked off a storm slab a couple of inches thick from his skis a few feet to his right against the wall of the chute. After a jump turn into a ski cut to one of those protected spots, he triggered a larger storm slab about 4” thick that propagated from the edge of our boot pack on one wall of the chute to the other wall about 20/30’ across and then ran the rest of the chute onto the apron about 300’ below us. No one was caught or injured. We skied out of the chute on the crust bed surface and spent the rest of the day enjoying some low angle trees. The chute was around 40° at 9,000’-9,500’ and west facing. We also noted a point release on an east aspect at about 9,300’ off the ridge separating Beehive and Middle Basin. It looked like a block of snow fell from a south facing cliff onto the slope below. 


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Northern Gallatin
Mt Blackmore
Cornice triggered avalanche north of Mt. Blackmore
Incident details include images
Incident details contain video
Mt Blackmore
HS-ACc-R3-D2-O
Elevation: 8,700
Aspect: E
Coordinates: 45.4564, -111.0180
Caught: 0 ; Buried: 0

From an email:

We were still hesitant of our results from our snowpit so we decided to cut a cornice that would drop onto the slope below, which I'm estimating to be 40 degrees. We released a cornice that tumbled downslope. The cornice went roughly a quarter of the way downslope before triggering a hard slab avalanche that broke just below the corniced ridgline. The avalanche propagated on both sides of the path and propagated further downslope. The avalanche ran into the flats and flanked in two directions once the slope widened (which I've included in the map below). 
 
We were unable to assess the crown in detail since we weren't comfortable with the amount of hangfire above, but estimate it to be 150 feet wide, running 1000 feet slope distance and roughly 600 vertical feet. The avalanche failed on the persistent weak layer interface that we had doubts about. 
 
 
20200307 @ 12:30pm
Crown:
45.4626N, -111,0219W
8766'

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Out of Advisory Area
Pine Creek
Natural wet avalanches in Pine Creek, Livingston
Incident details include images
Pine Creek
WL-Nu
Coordinates: 45.4904, -110.4850
Caught: 0 ; Buried: 0

My partner and I were snowshoeing to Pine Creek Lake on Saturday 3/7 when we came across a large amount of avalanche debris piled up in the creek bed/gully of the north fork of Pine Creek. The toe of the debris started approximately right where the normal summer trail crosses the Pine Creek, and ran for probably a couple hundred feet up the creek bed. As we paralleled the creek on the south side, we could eventually see where it looked like the avalanche started, far up on the ridge to the north of the creek, at least another 1000 feet above. The debris looked fresh and very chunky/wet. That Saturday was very warm and sunny. We experienced a few small whumphs/collapses as we hiked up the south side of the creek. We ran into a couple other parties of skiers, but none of them commented on any other particular instabilities higher up towards Black Mtn.


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Cooke City
COOKE CITY
Natural wet loose near Cooke and Livingston
Incident details include images
COOKE CITY
WL-N-R1-D1.5-G
Elevation: 7,500
Coordinates: 45.0202, -109.9380
Caught: 0 ; Buried: 0

From email: "[Near Mill Creek] We saw a natural wet slab that had released recently on a nw slope at around 7000’ (WS-N-R1-D1.5-G). Also got a big collapse on a sw aspect at about 7500’ on a moist layer of 4mm depth hoar. HS was only about 50cm where I got the collapse. Overall the snow was some wet hot garbage on all aspects,..."

Separate email: "Photo attached of some wet loose avy activity observed today just west of Cooke City (south aspect, around 8200').  Overall though, minimal wet avalanche activity observed with this significant warm up. No additional slab avalanche activity observed this week,..."


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Many small wet loose slides
Incident details include images
WL-N-R1-D1
Caught: 0 ; Buried: 0

Numerous small wet loose avalanches on 3/6/2020. 

S. Gallatins  - from email: "Five small wet slides across the big sky trail in Buffalo Horn this afternoon. The biggest was probably 120’ long and 50’ wide."  

Bridgers  - "Saw some small avalanche activity. A few wet loose on east to south aspects... Wet loose activity I saw was D1 on Bridger peak from below high cliffs. 2x D1.5s in Argentina Bowl. and 2-3 other D1s near the Throne. Largest was on the Hollywood Wall in Frazier where I saw a debris pile of D2 size, but can’t tell if it was loose or slab."

S. Madisons - "Slopes across from Bacon Rind. 8 or so natural D1 wet slides. Points releases to small wet slabs."


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Bridger Range
Ross Peak
Small skier triggered wet loose slides in Bridgers
Ross Peak
WL-AS-R1-D1
Aspect: S
Coordinates: 45.8586, -110.9560
Caught: 0 ; Buried: 0

From email: "Steep south facing slopes would readily push small loose wet slides if you were skiing it, all other solar slopes took heat but didn’t seem to heighten the avalanche danger. "


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Southern Madison
Skyline Ridge
Cracking wind slab on Skyline Ridge
Incident details include images
Skyline Ridge
Coordinates: 44.9205, -111.2300
Caught: 0 ; Buried: 0

From obs: "On Thursday my group skied a few lines off the Lee side of skyline. Generally, all stability observations but one were good except for 1. We were skinning cross slope along the top of the apron toward the bottom of a couloir on the north aspect of White Peak to recon the couloir for possible ascent and skiing. As we approached the opening of the couloir, a large collapse occurred on a firm wind slab and a crack shot out across the bottom of the couloir an unknown distance. (We deemed it unwise to further investigate given the slope angle was nearly 40 degrees. It was quite puzzling the slope did not slide upon collapse and we were not about to further poke that bear.)"


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Cooke City
Sheep Mountain
Cornice triggered wind slab near Cooke
Sheep Mountain
HS-NC-R1-D1
Coordinates: 45.0722, -109.9280
Caught: 0 ; Buried: 0

From email "Cornice releases off Sheep Mountain that stepped down and released a wind slab within the start zone."


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Northern Madison
Buck Ridge
Natural Cornice Collapse in 2nd Yellowmule
Incident details include images
Incident details contain video
Buck Ridge
C-NC-R1-D1.5-S
Elevation: 9,250
Aspect: NE
Coordinates: 45.1807, -111.4090
Caught: 0 ; Buried: 0

Cornices are growing very large in Buck Ridge area. This one failed about 100' across and took a bit of wind pillow with it, but did not break into deeper weak layers. 


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Out of Advisory Area
Natural above East rosebud lake
NC
Aspect: NE
Coordinates: 45.1842, -109.6760
Caught: 0 ; Buried: 0

Reported on 3/1/20 Likely 1-2 weeks old: "We saw a massive cornice triggered slide with a crown of roughly 20-30ft on a NE aspect above East rosebud lake."


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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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Southern Gallatin
Ramshorn Peak
Cornice triggered avalanche on Ramshorn Peak
Incident details include images
Ramshorn Peak
HS-NC-R2-D2
Aspect: E
Coordinates: 45.1534, -111.0930
Caught: 0 ; Buried: 0

The date of the avalanche is a best guess based on other activity.

From an email, " It did look like the east face of Ramshorn Peak slid pretty recently. The blowing snow and clouds weren't conducive to good pictures but you can see the crown line below and to the right of the summit. Looked like a cornice fall triggered it."


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Cooke City
COOKE CITY
Natural small wind slab and dry loose near Cooke
Incident details include images
COOKE CITY
SS-N-R1-D1.5-S
Elevation: 9,300
Aspect: NE
Coordinates: 45.0202, -109.9380
Caught: 0 ; Buried: 0

From email 2/28: "Photo attached of a natural avalanche from yesterday, just south of Cooke City.  It's on an E, NE aspect, with a crown around 9,300'.  Looks like it occurred yesterday am, as a result of a cornice fall.  

Additionally we observed quite a few natural, point release avalanches on mid elevation easterly aspects yesterday too.  Lots of sunshine, and temperatures in the valley bottom slightly above freezing yesterday.

Overall we didn't find the fresh wind drifts to be too widespread though."


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Southern Gallatin
Specimen Creek
Big collapse at Specimen Creek
Specimen Creek
Coordinates: 45.0265, -111.0480
Caught: 0 ; Buried: 0

From email: "Very Substantial collapse and shooting crack on a SW facing meadow on a 30 degree slope around 8700’ acting on DH. Crack separated around an inch and a half."


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Out of Advisory Area
Black Mountain
Skier triggered small slab and natural loose on Black Mtn. Absaroka
Incident details include images
Black Mountain
SS-AS-R1-D1-S
Elevation: 9,000
Aspect: S
Coordinates: 45.1628, -111.5290
Caught: 0 ; Buried: 0

While approaching Black Mountain from Pine Creek Lake. Noticed two dry loose snow problems on the way up near rock bands on North facing aspects at 9500'. R1.5 D1. Winds were powerful around 30mph at the summit and on the approach our major concern was wind slab problem reacting around 5 inches deep. We skied South aspect and as it warmed we triggered D1 R1 slabs that ran slow and short. Although we never skied on substantial slabs, we were eager to get moving and out of any run outs.


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Northern Gallatin
Divide Cirque
Natural avalanche in Divide Cirque
Incident details include images
Divide Cirque
SS-N-R2-D2.5-O
Elevation: 9,300
Aspect: NW
Coordinates: 45.3934, -110.9690
Caught: 0 ; Buried: 0

Timing uncertain, but the avalanche occurred sometime after the last significant snowfall on Tuesday 2/25/2020.

From observation: "Saw this avalanche that broke on a NW facing slope around 9300’. Looks to have failed on the facets at the ground ... the crown was 4-5’."


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Bridger Range
Hourglass Chute
Cornice triggered avalanche in Hourglass, Bridgers
Incident details include images
Hourglass Chute
HS-NC-R3-D2.5-O
Elevation: 8,300
Aspect: E
Coordinates: 45.8330, -110.9380
Caught: 0 ; Buried: 0

HS-R3-D3

3-4’ crown skiers left usual wind loaded side appeared to be started by a natural cornice drop.
 
There was a 4-5’ crown lower below the pinch on the skiers right wall. The toe of the debris stopped just short of the low meadow. It appeared that it ran on the November rain crust
 
3 people who did not witness anything but skied up on the crown at 3:40ish performed a transceiver search with no results. It appeared that the avalanche was a few hours old. 
 

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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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Out of Advisory Area
Black Butte- Gravelly Range
Snowmobile Triggered Avalanche in the Gravelly Range
Incident details include images
Black Butte- Gravelly Range
HS-AMu-R2-D2-O
Elevation: 9,100
Aspect: S
Coordinates: 44.8726, -111.8190
Caught: 0 ; Buried: 0

Isolated 5' crown, ran 100 yards wide.


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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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Southern Gallatin
Specimen Creek
Small natural wet loose and wind slab in S. Gallatins
Specimen Creek
WL-N-R1-D1
Elevation: 8,500
Aspect: S
Coordinates: 45.0265, -111.0480
Caught: 0 ; Buried: 0

From an obs on 2/23/20: "...today toured up above 9000 ft on Meldrum and some surrounding hills.... No cracking, collapsing, or naturals observed aside from some small wet loose that occurred yesterday in steep S rocky terrain at 8500 ft.... HS 150+ with depth hoar 130 down. The new snow will be falling on a variety of snow surfaces from crusts (E-S-W) to wind board (ridgelines) to NSFs (N). Temperatures warmed to above freezing today to at least 9000 ft. Winds increased to moderate out of the west by 1400 with some wind transport occurring at ridgelines."

From another group on Electric Peak on 2/23/20: "One recent natural avalanche near the ridgeline roughly 30 cm deep probably due to wind loading (D1) and a handful of natural loose wet (D1) avalanches on southerly aspects. Dug a quick pit on the face (10700’ NE 30 degree slope HS 190cm) and got an ECTP23 @ 35 below the surface on a hardness change below a 1F fresh windslab... Also, bulletproof windboard below the first roll (@10200’) and cranking winds!"


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Northern Madison
Sphinx Mountain
Natural avalanche on Sphinx
Incident details include images
Sphinx Mountain
HS-N-R3-D3-O
Elevation: 9,000
Aspect: SW
Coordinates: 45.1582, -111.4770
Caught: 0 ; Buried: 0

On sunday 2/23/20 skiers near Sphinx Mtn. saw a recent  2-4' deep natural avalanche that broke on old persistent weak layers. Best estimate for timing is between 2/16 and 2/22. from IG: @skishot


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Cooke City
Wolverine Peak
Natural on Wolverine Peak Cooke City
Wolverine Peak
Coordinates: 45.0530, -110.0100
Caught: 0 ; Buried: 0

"While sled skiing a bowl over, we noticed the second half of a natural slide. We forgot to go over and take photos, but it seemed like it was either a cornice break or a point release, and slid somewhere around 1,000 feet."


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Lionhead Range
LIONHEAD AREA
Snowmobile triggered small slope Lionhead
LIONHEAD AREA
SS-AMu-R2-D2
Coordinates: 44.7292, -111.3230
Caught: 0 ; Buried: 0

From IG message: "Was riding up lions head today. Was on the same channel as another group and a member of their group came over the radio and said that he had to roll his sled and it triggered/buried his sled. Didn’t get much more info but he was very spooked over the radio. Looked hard on our way out and couldn’t find the slide."


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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
Skier triggered slab near Cooke
Incident details include images
COOKE CITY
SS-AS-R2-D1.5-I
Elevation: 8,000
Aspect: S
Coordinates: 45.0202, -109.9380
Caught: 0 ; Buried: 0

From email on 2/21/20: "...observed today from the highway. It appears like it was probably triggered by a skier yesterday (on Feb. 20).  It was on a south aspect around 8,000', and estimated to be 1-2' deep and about 30' wide.

Additionally, there were a couple of wet, point release avalanches that ran today on other southerly aspects,  due to abundant sunshine and warming temps.  Aside from that, no other slab avalanche activity nor signs of instability observed this last week around Cooke City."


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Out of Advisory Area
Pine Creek
Natural avalanche Pine Creek
Incident details include images
Pine Creek
HS-N-R3-D2-O
Elevation: 9,700
Coordinates: 45.4900, -110.4950
Caught: 0 ; Buried: 0
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Northern Gallatin
Storm Castle
Naturals in Storm Castle Creek
Incident details include images
Storm Castle
SS-N-R3-D2-O
Elevation: 8,500
Coordinates: 45.4504, -111.2240
Caught: 0 ; Buried: 0

On Saturday 2/22/20 riders saw natural slides on east and west aspects 10 miles up Storm Castle creek. 


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Northern Madison
Wilson Peak
Natural Avalanches, Wilson Peak
Incident details include images
Wilson Peak
HS-N-R2-D2.5-U
Elevation: 10,200
Aspect: S
Coordinates: 45.3270, -111.3250
Caught: 0 ; Buried: 0

By far the most interesting thing today is an avalanche cycle on the south face of Wilson Peak. Multiple avalanches, some breaking on planar faces, scattered all across the thing. Not sure on depth either- some look quite deep, but I’m wondering if it is the storm snow from the mega-storm 2 weeks ago running on the rock hard surface leftover from the 100+ mph wind event 2.5 weeks ago. We will look more closely with binoculars tomorrow for a better estimate of scale. The slopes were obviously cross-loaded, but we were interested in what exactly made them cycle today (or last night).


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Bridger Range
Flathead Pass
Naturals near Flathead Pass
Incident details include images
Flathead Pass
HS-N-R3-D2.5-O
Elevation: 8,000
Aspect: NE
Coordinates: 45.9684, -111.0210
Caught: 0 ; Buried: 0

Natural avalanche crowns were seen on 2/20/2020 near Flathead Pass that appear to be from the last 2-3 days. They were fresher than crowns that were seen here on 2/9, and these slopes had not slid when the area was visited on 2/9.


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Out of Advisory Area
Other place
Natural Avalanche in Absarokas
Incident details include images
Other place
HS-N-R3-D3-O
Elevation: 9,700
Aspect: NE
Coordinates: 45.6553, -110.5580
Caught: 0 ; Buried: 0

From IG #gnfacobs post: "An avalanche from early Tuesday (02/18) morning caused by a natural cornice fall. Note the step down partway down the path. ENE @ 9700. Ran 1300’." 


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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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Northern Gallatin
Maid of the Mist
Big Deep Slabs in Maid of the Mist, Hyalite
Incident details include images
Incident details contain video
Maid of the Mist
HS-N-R4-D3.5-O
Elevation: 9,900
Aspect: SE
Coordinates: 45.4164, -110.9700
Caught: 0 ; Buried: 0

Skiers saw these deep slabs in Maid of the Mist in Hyalite on 2/21/20. Doug Chabot went to the site on the 2/22.

The avalanches were big and deep. They ran on the facets/depth hoar near the ground. The slide (1&2) ran to their maximum runout.

Aspect: South to East

Elevation: 9900'

Slope Angle: estimated 45+ degrees at the steepest with average of 40 degrees.

Using Google Earth

Crown: 9930'

Toe of Debris: 9316' with a measured Alpha Angle of 16 degrees

  • Latitude:  45°24'49.65"N
  • Longitude: 110°58'49.04"W

Using picture "4 avalanches..." as reference:

  1. was 300' wide, 6-8 feet deep
  2. 1300' wide; it ran from east to south aspect; was 10-12 feet deep; ran 2150' slope distance,
  3. was 150' wide, 450' slope distance, 4-5 feet deep
  4. was 250' wide and had a measured Alpha Angle of 26 degrees, 4-5 feet deep and ran 775 slope distance.

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Bridger Range
Wolverine Bowl
Wolverine Bowl natural avalanche, Bridgers
Incident details include images
Wolverine Bowl
SS-N-R2-D2-O
Elevation: 8,400
Aspect: E
Coordinates: 45.8301, -110.9340
Caught: 0 ; Buried: 0

"We came across the debris of a significant slide in one of the steeper lines just north of Wolverine bowl today. There was zero new fallen snow on the debris so it happened sometime this morning before 11:30 a.m. and after the snowfall stopped last night. The multiple crowns looked to be 3-5 feet tall and a large tree has been jammed into the tube ride chute. The toe of the debris is all the way down into the creek at the base of Wolverine. It's possible a large cornice broke off at the ridgeline but we couldn't get eyes on the actual start of the slide. We skinned up and down the debris pile twice while in search mode at around 12:30 but did not pick up a signal. We did not investigate above the pinch of the chute and into the upper part of the slide. The debris pile is quite deep with some damaged trees. We did 6 lines off the ramp over the weekend and did not see any other avalanche activity but obviously some significant wind loading."


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Out of Advisory Area
Emigrant Peak
Many large, destructive slides on Emigrant Peak
Incident details include images
Emigrant Peak
HS-N-R4-D3-O
Elevation: 9,800
Coordinates: 45.2630, -110.7070
Caught: 0 ; Buried: 0

[date of activity roughly estimated] From email on 2/22/2020: "The mountains around Emigrant Peak have certainly reached their tipping point. Skinning up in the morning we witnessed the debris of more than a dozen avalanches on all aspects, more than I have ever seen in a single day. Many of these avalanches were extremely large and powerful deep slabs that broke towards the ground, likely to have released within the past week. Slides were running to the end of their runout zones and carried with them many trees that were torn to shreds."


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Northern Gallatin
Chestnut Mountain
Natural avalanche on Chestnut Mountain, N. Gallatins
Incident details include images
Chestnut Mountain
SS-N-R4-D2-O
Elevation: 7,000
Aspect: E
Coordinates: 45.6057, -110.8810
Caught: 0 ; Buried: 0

From an observation, "R3-4 D2 avalanche that failed at the ground observed from the Trail Creek Rd. Looked to be several hundred feet wide, couldn’t see the debris, but crown went through lots of trees." 


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Northern Gallatin
Mt Blackmore
Shooting cracks on Mt Blackmore
Incident details include images
Mt Blackmore
Coordinates: 45.4444, -111.0040
Caught: 0 ; Buried: 0

"Toured up Blackmore today, we had shooting cracks under our feet along the north east ridge line."


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Out of Advisory Area
Natural Avalanche Mill Creek, Absarokas
Incident details include images
Caught: 0 ; Buried: 0

"We observed an avalanche on a southeast face while touring in the Absorokas. The avalanche appeared to be naturally triggered earlier in the morning as there were no tracks and my partner and I was the only party in the area today. The avalanche appeared to break on the ground, was about 200 feet wide and ran 600 feet. It was the only avalanche we observed today and was on a relatively shallow slope compared to other regions. We had observed widespread whumpfing and collapses throughout the day."


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Northern Gallatin
Mt Ellis
Collapsing/Whumphing at Bear Canyon
Mt Ellis
Elevation: 6,800
Coordinates: 45.5777, -110.9550
Caught: 0 ; Buried: 0

A group reported: "On Sunday afternoon my partner and I skinned up Bear Canyon and proceeded a half mile south along the ridge from the top of the ski hill. We were considering skiing a treed gully off the ridge down into Shoefelt gulch or skiing the East side of the ridge back into New World Gulch. As we skinned out of the trees (@ 6,800 ft) and out into the meadow above our prospective runs I caused a very audile collapse and it was obvious the wind had done a lot of work moving snow on to the east facing slope. We dug a snow pit, on a west facing slope, about 30 feet down from the ridge. The snowpack in our pit was 95CM deep, we did an extended column test and got an ECTP 13 which failed on the facets near the ground. The slab was ~70 CM. We decided to dig another pit on the east facing slope just across the ridge, making sure not to get too close to gully which looks like a slide path. My partner dug out the majority of the pit and then I joined him to perform another ECT. Just before we isolated our column my partner stepped out of the pit for a second and on he triggered another extremely audible collapse that seemed to have traveled a decent ways across the slope to the north of us, towards the gully. We got an ECTP 12 from this pit, it broke on the facets near the ground and the slab was about 80CM, the snow depth was 100CM. I thought it was interesting that we did not see much cracking while we were skinning or digging our pits, that being said the new snow from this last storm cycle was very dense and it was easy to get it to sheer when we were digging pits but we did not see it collapse. We knew going up that we probably couldn't ski any of what we checked out but had good time looking at the snowpack and skiing with the dogs back down the ridge to Bear Canyon."


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Southern Gallatin
Big Horn Peak
Collapsing and cracking in the southern Gallatins
Big Horn Peak
Coordinates: 45.0668, -111.0500
Caught: 0 ; Buried: 0

1. Massive rolling collapse on lower ridge of ascent on Big Horn Peak. Felt like it went out hundreds of yards uphill. No avy activity. Other various collapses while skinning up ridge. 2+ weeks ago the lower ridge only had about 40-50 cms on it, so was not surprised to have that happen after large amounts of loading.

2. Specimen Creek: Heard several whumpfs and saw shooting cracks. No avalanche triggered, but a very unstable snowpack. Some whumpfs traveled farther than others. Very deep snow, fell to about knee height on parts of the trail, even in snowshoes...many shooting cracks and loud, traveling whumpfs as well as shaking ground from settling snow. This was relatively far from avalanche terrain on flat ground. Snowpack very unstable.


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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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Bridger Range
Flathead Pass
Big natural avalanches on Flathead Pass
Incident details include images
Flathead Pass
HS-N-R4-D3-O
Elevation: 8,000
Aspect: NE
Coordinates: 45.9684, -111.0210
Caught: 0 ; Buried: 0

"Quick Obs from a tour up to the skiing just south of Flathead Pass [2/17/2020]. We headed that direction for some low-angle protected tree skiing and, instead, found evidence of a widespread natural avalanche cycle from 2~3 days ago.

There were 3 main avalanches with similar characteristics: HS - N - R4 - D3 - O. 

- Crowns topped out around 8000’ with large amounts of hanging snow (on steep slopes) above. Interestingly, the crowns connected down slope as low as 7800’ and jumped from tree to tree along convexities. The avalanches’ crowns ranged from 100’ wide to over 500’ wide.

- The avalanches failed on 4F- 1.5mm facets above the Thanksgiving crust, which was substantially harder than I have seen in the southern Bridgers.

- The avalanches stepped down to well-developed depth hoar (below the crust) in a few locations.

- The average crown depth was ~140cm where we felt safe looking (near bottom of crown) but was significantly more shallow near some trees.

- Conducted a quick crown profile and some tests. The standout results are PST 25/120 END x3 (we conducted the PST at a spot where the weak layer was buried 120cm deep) on the persistent weak layer with no notable results in two separate location ECTs and additional deep tapping…).

- The debris piles extended to previous old-growth maximums (extending the path of at least one avalanche) and had many snapped trees up to 10” in diameter deposited within."


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Northern Gallatin
Mt Blackmore
Many natural avalanches on Mt Blackmore
Incident details include images
Incident details contain video
Mt Blackmore
HS-N-R4-D3-O
Elevation: 9,400
Coordinates: 45.4467, -111.0040
Caught: 0 ; Buried: 0

From an observation on 2/16: "My partner and I skied off the north-north east ridge of Mt Blackmore into the Fox Creek drainage and observed five recent, naturally-triggered avalanches from the recent storm. Three D1 avalanches were scattered across the bowl from the north, northeast and north-northeast aspects next to exposed rock-outcroppings but were too small to capture in a photo. A fourth, D3 R3 avalanche occurred at approximately 9200' on the north aspect that appeared to have broken right at the bedrock and slid approximately 200 vertical feet. Crown looked to be up to 6' deep and 600 feet across. The fifth, D3 R4 avalanche occurred at approximately 9400' on the north-northwest facing aspect in a narrow meadow. Crown was approximately 8' deep and 30 feet across (the width of the meadow). There was rapid wind-loading still occurring on the aspects of the two D3 avalanches covering up their slide paths and we observed significant wind-loading and cracking off the northeast ridge line."

From a separate group on 2/16: "Took a walk up near Blackmore today to take a look at a NE facing aspect. We did not ski our objective because we observed active wind loading and saw many recent avalanches.

The first picture is looking at Alex Lowe Peak from the west ridge of Elephant. There were 5 avalanches clearly visible. I highlighted the crowns/debris paths with red.

The second picture is a close up of the avalanche on the ridge between Elephant and Blackmore on a south aspect. This one was the largest and the most fresh. All avalanches appeared to be naturally triggered from wind loading.

We also saw an avalanche looking north from the NE ridge of Elephant over the east ridge of Blackmore. The avalanche was on a south/southeast facing hill and looked like it broke at the ground. It was pretty sizable. We didn't get a picture, but this looks like it would've been visible from the east ridge of Blackmore looking north."

Forecasters visited the area on 2/21/2020: Saw over 15 old avalanches. Estimate an additional 8 that the above groups did not report, so a total of 18+ in the area during the cycle.


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Northern Madison
Black Mountain
Collapsing and Cracking on Black Mtn, N Madison
Black Mountain
Coordinates: 45.1628, -111.5290
Caught: 0 ; Buried: 0

While touring up black mountain on Saturday, February 15th 2020, our group heard very loud whoofing on flat ground, collapsing large areas. There was small cracks formed but we were on very low angle slopes. We switched to a back-up plan to get down. A second large whoofing occurred minutes later a short distance away from the first. This time we could feel the snow drop below us by a few inches. We turned around and followed our tracks down. We dug two pits in the vicinity of the collapsing. Two extended column tests produced failures on the same depth hoar at the ground, ECTP 23 and ECTP 16. The latter result was on a pit of at least a meter deep. WE collapsed another flat while skiing down. No other obvious signs of instability were seen.


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Northern Madison
Bear Basin
Large natural avalanche in Middle/Bear Basin
Incident details include images
Bear Basin
HS-N-R4-D2.5-O
Elevation: 9,500
Aspect: NE
Coordinates: 45.3344, -111.3720
Caught: 0 ; Buried: 0

We encountered a natural avalanche that appears to have been triggered by a cornice drop. There seemed to be very little fresh snow on the slide surface so we suspect it occurred recently (Feb 14?). The slide occurred on the west side (east facing side) of Bear Basin (pinpoint on the map below). The avalanche was probably 200 feet wide at the top so it clearly propagate across the slope. Crown was 2 to 5 feet tall. We did not hike in there to investigate more carefully. There is a fair amount of trees on this part of the ridge. The picture shows how some large chunks got hung up on trees but we could see that the slide ran across the creek below (almost 1000 vertical feet). We had planned on skiing this slope and/or the open meadow (talus field) a hundred yards north but in light of this observation we turned around, skied back down in Middle Basin in the trees. Side note: we dug a pit earlier on an almost identical aspect (on the Beehive/Middle basin ridge) and obtained ECTN 16 @ 12" below the surface, ECTN 23 @4" below that, ECTN 28 @ 6" below that... Basically some definition between the latest storm layers but no propagation, and a right-side up snow pack. We only dug about 3 feet deep so this pit did not assess the ground level facets, which we figure are wide spread. The natural slide we encountered one ridge over seemed to be a case where a thin area was triggered by a cornice drop.


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Northern Gallatin
Lick Creek
Natural avalanche east of the top of Lick Creek
Incident details include images
Lick Creek
SS-N-R2-D1.5
Aspect: W
Coordinates: 45.5243, -110.9560
Caught: 0 ; Buried: 0

From an observation, "This activity appears to have occurred naturally. No signs of a skin track or skiing. No accurate indication of when it happened, tho appeared fairly recent with no new wind loading." 


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Cooke City
Woody Ridge
Large natural on E side Woody Ridge, Cooke
Woody Ridge
SS-N-R1-D2-O
Elevation: 10,200
Aspect: E
Coordinates: 44.9739, -109.9240
Caught: 0 ; Buried: 0

From an observation, " Climax slid quite large several days ago. We could get a good look at the crown because of the wind, but I’m guessing it was a wind slab that stepped down."

"Climax" is the what the locals call the large east face on Woody Ridge above Hayden Creek.


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Northern Gallatin
Moose Jaw
Natural Avalanche up Moose Jaw, Storm Castle Ridge
Incident details include images
Incident details contain video
Moose Jaw
HS-N-R3-D3-O
Elevation: 9,200
Aspect: N
Coordinates: 45.4494, -111.0760
Caught: 0 ; Buried: 0

Very large avalanche photographed from Gallatin Gateway at the head of Little Bear Canyon. This avalanche likely occurred Saturday or Sunday during the loading event as there is snow on the debris pile. 


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Northern Gallatin
Divide Cirque
Large natural avalanche in Divide Basin, Hyalite
Incident details include images
Divide Cirque
HS-NC-R5-D3-O
Elevation: 10,000
Aspect: E
Coordinates: 45.3934, -110.9690
Caught: 0 ; Buried: 0

1. Observed a sizable deep slab in the Divide basin which appeared to have run within the last few days. The crown extended from the southern end of the basin (northeast facing) through the summit run off Divide (southeast facing)--maybe around a mile. Slab height varied, with the upper end pushing 10 feet and the lower closer to a foot or two. On Divide, the crown approached the summit and debris had run across the flat to the mature trees. Looked like it may have been cornice triggered at the southern end on thinner cover in rocky terrain.

2. Skied the NE shoulder of Divide Peak. Spotted a 1/4 to 1/2 mile long crown spotted along the NE face of Peak 10,024, between Divide Peak and Hyalite Peak. We could not directly determine the crown height, but it was highly visible from our location ~1 mile away.

3. Several large avalanches along the west ridge of divide basin. Appeared to be set off by large cornice drops that propagated across the bowls and stepped down several feet into the snowpack.


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Northern Gallatin
Alex Lowe Peak
Natural avalanche on Alex Lowe Peak
Incident details include images
Alex Lowe Peak
HS-N-R4-D3-O
Elevation: 9,600
Aspect: N
Coordinates: 45.4272, -111.0140
Caught: 0 ; Buried: 0

From an email:

"Near the ridge line of Mt. Blackmore we noticed the East facing slope close to the ridge line was clearly wind loaded and felt collapsing and cracking under our skis. None of those cracks shot out however. We dug a pit on an E- SE facing slope near the ridge line and found no signs of stability, however we ran into a group on our way up who said they dug a pit in a similar area and got an ECTP-22. Looking N-NW from the ridge line we saw some an avalanche crown on the adjacent face (Alex Lowe Peak)."

This is the second time this avalanche path released. See a photo from 1/25/20 HERE.


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Out of Advisory Area
Knowles Peak
2 slides in a week on Knowles Peak, Paradise Valley
Incident details include images
Knowles Peak
HS-N-R4-D3-O
Aspect: N
Coordinates: 45.3048, -110.5430
Caught: 0 ; Buried: 0

1. "Large (presumably natural) avalanche seen on the north face of Knowles. 3ft deep crown, 300ft wide and probably a 100k ft run. Multiple broken trees in the debrisfield. Collapsing on 4" of sugary facets at the ground. Cracking, whoomphing, collapsing, etc found on all aspects on the ascent."

2. Photo is from February 12, Knowles Peak from Moo Creek.


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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
Wheeler Mountain
Two large slides on Wheeler Mtn
Incident details include images
Wheeler Mountain
N-R4-D3.5-O
Elevation: 7,900
Aspect: S
Coordinates: 45.5090, -111.0670
Caught: 0 ; Buried: 0

We skied Wheeler via South Cottonwood and found that the two gullies on the East and South East aspects had recently run in their entirety. We could only see the crown on the South East gully but it appeared to have broke on the steepest part of the slope near the top approximate 3-4ft deep and was the width of the gully. Both avalanches ran the full length and width of their gullies, breaking several trees along the way. The East debris pile was about 25ft deep and the South East was 15ft deep. The East rounded the corner into the ravine at the bottom and also ran about 200ft into the forest. A couple larger trees in the path that were not broken had their branches stripped off the bottom 30ft. Interestingly, the narrow meadow between the South East gully and the South East meadow you recently reported slides on has not slid. Also, we had no propagation or collapsing in our pits.


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Northern Madison
Yellow Mountain
Cornice fall triggered soft slab slab in Spanish Peaks
Incident details include images
Yellow Mountain
SS-NC-R3-D2
Elevation: 9,300
Aspect: S
Coordinates: 45.2995, -111.3200
Caught: 0 ; Buried: 0

Cornice fall triggered a soft slab avalanche in the Spanish Peaks on the afternoon of 2/13/2020.

From email: "100 feet wide, slid the new snow layer maybe 2-3 feet deep, made a pretty good runnel, and went close to full path , so it must have entrained a decent amount of snow to travel that far .."


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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 Gallatin
Mt Ellis
Collapsing and Cracking on Mt. Ellis
Incident details include images
Incident details contain video
Mt Ellis
Elevation: 8,000
Aspect: E
Coordinates: 45.5777, -110.9550
Caught: 0 ; Buried: 0

"I observed this collapse & propagation as I stepped over some wood in the skinner on the north ridge of Mount Ellis this morning, ~8000’, due East. I was tailing Chabot and his partner, and they had passed this way just minutes before."


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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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Cooke City
COOKE CITY
Small natural and human triggered avalanches in Cooke
Incident details include images
COOKE CITY
SS-N-R2-D2
Coordinates: 45.0202, -109.9380
Caught: 0 ; Buried: 0

1. "...a fresh avalanche observed out there today.  A south aspect around 9400', estimated to be 2-3' deep and 75' wide. Also observed 2 thinner wind slab avalanches that also ran naturally within the last 48 hrs, and were both about 1' deep and 50' wide.  One was a SE aspect, and one was a North aspect." See attached photo Natural avalanche 2-3' deep.

2. "We’ve seen many instances of cracking and wind slab breaks the past two days riding in Cooke, most happened as we sledded past or down the slope. The 1st and 2nd photo are 4” deep breaks at most. The last photo/slide we observed today, S facing slope, not sure how it was triggered, a foot deep crown at most." See attached photos Small 1' deep, Human triggered 1&2.


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Bridger Range
Flathead Pass
Many naturals near Flathead Pass
Incident details include images
Flathead Pass
HS-N-R3-D2.5-O
Elevation: 8,000
Aspect: NE
Coordinates: 45.9684, -111.0210
Caught: 0 ; Buried: 0

We drove to Flathead Pass to look for avalanches from the recent storm and saw widespread crowns that were fresh enough to have ran during the end of the storm. A couple broke in the 3 feet of storm snow, b ut many were 3-5' deep on persistent weak layers.


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Northern Gallatin
Mt Ellis
Collapsing and cracking on Little Ellis
Mt Ellis
Coordinates: 45.5777, -110.9550
Caught: 0 ; Buried: 0

Two parties reported, "Widespread wumphing and cracking on Little Ellis (both on the north side and east facing meadow above)." and "We skinned up the road and planned to ski the eastern meadow below Little Ellis. As soon as we began skinning the meadow, heard, and felt, a significant "whomp" so decided to play it safe and leave the area."


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Bridger Range
Ross Peak
Wind slab avalanche on Ross Peak, Bridgers
Ross Peak
SS-N-S
Elevation: 9,000
Aspect: NE
Coordinates: 45.8586, -110.9560
Caught: 0 ; Buried: 0

"Skied the low angle trees on the NW side of Ross today around 8000 ft. Saw a natural wind slab that had released during the day around 9000 ft. NE aspect, I'd estimate 40 degree slope but I wasn't very close. Moderate to strong winds most of the day."


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Southern Madison
Tepee Basin
Small avalanches in Tepee Basin, N. Madison
Incident details include images
Tepee Basin
SS-AMu
Coordinates: 44.9041, -111.1850
Caught: 0 ; Buried: 0

"...were up in Tepee today, we saw a couple small slides the one below look to be caused from a snowmobiler and we saw one other one high on the Whites peak ridge that looked to be a natural slide or maybe caused from a piece of cornice that broke off.  The rest of the ridge along White Peak also looked to be loaded up..."


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Bridger Range
Truman Gulch
Truman Gulch Natural Deep Slabs
Incident details include images
Incident details contain video
Truman Gulch
HS-N-R4-D3.5-O
Elevation: 8,500
Coordinates: 45.8139, -110.9330
Caught: 0 ; Buried: 0

Avalanche crowns spanned almost the entire ridge of Truman Gulch. They connected, but appeared to run at different times. The most recent was probably last night behind the Patrol lift. Looked very fresh today without any snow on it. In your face/Catch a wave was a day or two old.

All of Jones Crk also went as well as almost every sub ridge towards Ross Peak.


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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 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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Northern Madison
Cedar Mtn.
Natural avalanche on Cedar Mountian
Cedar Mtn.
SS-N
Coordinates: 45.2366, -111.5060
Caught: 0 ; Buried: 0

"Looking out from Big Sky I noticed two (possibly connected) crowns near the ridge top."


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Northern Madison
Beehive Peak
Natural Avalanches West of Beehive Peak
Incident details include images
Beehive Peak
SS-N-R3-D2-I
Elevation: 9,200
Aspect: SW
Coordinates: 45.3539, -111.4050
Caught: 0 ; Buried: 0; Killed: 0

From an obs.: "Large crown in lower meadows west side of beehive basin above jack creek. Both meadows in lower fight of photo went. Southwest aspect. Far right meadow crown is visible and entire face went. Left meadow is hard to see but 1/3 of face slid. I would guess 3-6 foot crown from how visible it was from moonlight."

Another report: "Observed good size crowns from Beehive Basin Road. They were on the west side of the ridge dividing Beehive Basin and Jack Creek. They were not down to the ground but big and wide looked like probably all the recent snow from the storm."


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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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Northern Gallatin
Elephant Mountain
Several avalanches on Elephant Mtn on way to Mt. Blackmore
Elephant Mountain
SS-N-D2-I
Elevation: 8,800
Aspect: NW
Coordinates: 45.4382, -110.9900
Caught: 0 ; Buried: 0

"Noted several avalanches (NW aspect ~ 8800') off of Elephant that traveled quite far into the trees where the summer trail typically runs, all appear to be new snow, D1- D2 in size, average 2' crowns, running on old/new interface from  Feb 2. They appear to have run midstorm, sometime yesterday (photos 1,2,3).  Above 9000', W Winds were crafting fresh wind slabs that were most reactive on a midstorm crystal/density change that buried a layer of stellars ~ 1' deep in shallower spots,  topped with denser snow." 


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Bridger Range
Texas Meadow
Natural 3' storm slabs north of Bridger
Incident details include images
Texas Meadow
SS-N-R3-D2.5-U
Elevation: 7,900
Aspect: E
Coordinates: 45.8406, -110.9330
Caught: 0 ; Buried: 0

We saw three natural avalanche crowns on the afternoon of 2/7/2020. The north half of Texas meadow broke 3' deep and two small pockets in the playground looked to be 3' deep. North of Bridger Bowl on an East aspects at 7,500'-7,900'. They probably occurred within the last 24-36 hrs.


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Northern Madison
Buck Ridge
Natural Avalanche in Muddy Creek, Buck Ridge
Incident details include images
Buck Ridge
SS-N-R4-D2-O
Aspect: NE
Coordinates: 45.1719, -111.3800
Caught: 0 ; Buried: 0

Natural avalanche. North facing slope. Around half mile wide. Photos don't show half of the slide. Broke on the ground facets. Crown was between 3 and 15 feet deep. We didn't get a photo of the deepest crown. Ripped trees out around 5" diameter.


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Northern Gallatin
Wheeler Mountain
Natural avalanches on Wheeler Mtn, N. Gallatin
Incident details include images
Incident details contain video
Wheeler Mountain
SS-N-R3-D2
Elevation: 8,000
Aspect: SE
Coordinates: 45.5097, -111.0820
Caught: 0 ; Buried: 0

"Noted two SS-D1.5/2 naturals (presuming based on lack of any sort of tracks) on Wheeler, typical spots for these conditions, both SE aspect around 8000'."

Dave Zinn dug a snowpit lookers right of the slides in the next path on Wednesday, 2/5, a couple days before the storm. He found weak snow that was ready to avalanche.


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Northern Madison
Small Natural storm snow avalanches in Gallatin Canyon
SS-N-R2-D1.5-I
Elevation: 6,000
Caught: 0 ; Buried: 0

On the drive to Buck Ridge there were widespread 4-6" deep natural slab avalanches in the storm snow on steep slopes, road cuts and river cuts. Some broke "on the ground", where it was bare ground two days ago. This is some evidence of the upside down nature of this storm.


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Bridger Range
Ross Peak
Natural avalanche near Ross Peak
Ross Peak
SS-N-R3-D2.5
Coordinates: 45.8586, -110.9560
Caught: 0 ; Buried: 0

Large natural avalanche on 2/6/2020 in between Ross Peak and the Throne. Knocked down several trees in the runout. 


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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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Bridger Range
Saddle Peak
Natural Deep Slab Saddle Peak
Incident details include images
Incident details contain video
Saddle Peak
HS-N-R3-D3.5-O
Elevation: 8,900
Aspect: NE
Coordinates: 45.7943, -110.9360
Caught: 0 ; Buried: 0

A natural 4-8' deep slab avalanche broke on Saddle Peak within the last couple days (2/6 or 2/7) during the current storm. The mountains received 3-5 feet of snow equal to 3-5" of SWE over the last week with more snow in the forecast.


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Northern Madison
Buck Ridge
Human triggered and natural on Buck Ridge
Incident details include images
Incident details contain video
Buck Ridge
SS-AMc-R2-D1.5-I
Elevation: 9,300
Aspect: NE
Coordinates: 45.1719, -111.3800
Caught: 0 ; Buried: 0

We triggered an avalanche in the second Yellow Mule off Buck Ridge on 2/6/2020. It is on a small roll/cornice "in the flats". It broke within the current 2-3' storm snow,18-24" deep.

We also saw a couple natural avalanche crowns 10-18" deep lower down the drainage. I'm sure there were a ton more crowns there, and probably everywhere. through the forecast area. Visibility was limited to 50-100'.


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Northern Gallatin
Mt Ellis
Widespread cracking and collapses on Little Ellis
Mt Ellis
Coordinates: 45.5777, -110.9550
Caught: 0 ; Buried: 0

From observation: "We had cracks shooting around our skis for the entire skin up, and multiple wumphs"


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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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Bridger Range
Flathead Pass
Collapsing, cracking and recent natural avalanche in northern Bridgers
Incident details include images
Flathead Pass
Coordinates: 45.9684, -111.0210
Caught: 0 ; Buried: 0

Skiers around Frazier Basin and also at Flathead Pass reported collapsing and cracking as they skied. From Flathead pass, "Lots of collapses and whumphs. Obvious soft slab fractures in new and drifted snow. Saw evidence of point release avalanches on steeper terrain around cliffs. Also saw a crown that appeared to have triggered on the new wind loaded snow, NE aspect. It was approx. 200 feet below a steep rocky ridge."


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Southern Madison
Tepee Basin
Small natural slide in Tepee Basin, S. Madison
Incident details include images
Tepee Basin
SS-N
Coordinates: 44.9041, -111.1850
Caught: 0 ; Buried: 0

This small natural avalanche was seen in Teepee basin on Tuesday, 2/4.


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Bridger Range
Saddle Peak
Natural Avalanche in Pinnacles, Bridger Range
Incident details include images
Saddle Peak
SS-N
Aspect: E
Coordinates: 45.7943, -110.9360
Caught: 0 ; Buried: 0
"I took this photo from the highway today just before noon 2/4/20. Looked pretty fresh and not blown in much and the winds were howling. Largest part of the crown looked 6-8' tall right in the center. It connected across a pretty low angle shoulder to pull out the northern bowl."

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Cooke City
COOKE CITY
Cooke City Deep Slab Natural
Incident details include images
COOKE CITY
HS-N-R2-D2-O
Elevation: 9,500
Aspect: W
Coordinates: 45.0202, -109.9380
Caught: 0 ; Buried: 0

West aspect around 9500'. Deep slab, mid-slope. Crown estimated to be 4-6' deep.


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Bridger Range
Truman Gulch
Natural Avalanches on the west side of the Bridger Range
Incident details include images
Truman Gulch
SS-N-R3-D2.5
Aspect: W
Coordinates: 45.8139, -110.9330
Caught: 0 ; Buried: 0

1.  "I saw two crowns from the ridge at 1430 today (2/4). One on the lower heavily wind loaded shoulder and one up high in the middle of the path. Not sure if they connected, or were separate. R3-D2.5. 2-4’ deep. The higher one was partially drifted in. My guess is ran yesterday with east winds or early today."

2.  "Saw this looking south from top of the ramp into Jones creek. Looks to be just new snow but couldn’t see the whole crown or the slide path."


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Cooke City
COOKE CITY
Cooke City Wind Slab
Incident details include images
COOKE CITY
SS-N-R1-D1-I
Elevation: 8,600
Aspect: SE
Coordinates: 45.0202, -109.9380
Caught: 0 ; Buried: 0

SEerly aspect around 8600'.  A thinner, smaller storm slab, triggered by dry loose from above.


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Bridger Range
Ross Peak
Natural avalanche near Ross Peak, Bridgers
Incident details include images
Ross Peak
SS-N
Aspect: E
Coordinates: 45.8586, -110.9560
Caught: 0 ; Buried: 0

This avalanche was seen on Tuesday, Feb 4 and likely released on Monday from the wind loading.


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Northern Madison
Other place
Natural Avalanche in Northern Madison Range
Incident details include images
Other place
SS-N
Aspect: E
Coordinates: 45.6553, -110.5580
Caught: 0 ; Buried: 0

East facing slope seen from Big Sky meadow after Sunday’s storm.


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Centennial Range
Reas Peak
Reas Peak - Natural Avalanche
Incident details include images
Reas Peak
HS-R3-D3-O
Elevation: 9,200
Aspect: SE
Coordinates: 44.5358, -111.5130
Caught: 0 ; Buried: 0
It cleared up and I took out my binoculars from our cabin on the west shore of Island Park Reservoir and noticed this huge slide in the bowl south of Reyes peak. Started at the little tree band below the ridge, takes out 1/3 of the bowl, and runs into the Blue Creek terrain trap. I assume this is a natural avalanche.

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Northern Gallatin
Hyalite - main fork
Small avalanche triggered in new snow by ice climber, Hyalite
Incident details include images
Hyalite - main fork
SS-NIu-R1-D1
Aspect: W
Coordinates: 45.4472, -110.9620
Caught: 0 ; Buried: 0

"Climber caused icefall that triggered small avalanche. Thankfully, the bed surface was ice just a few inches down and belayer was just outside the path. Minor entrainment."


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Bridger Range
The Great One
Natural avalanche in Great One, Bridger Range
Incident details include images
The Great One
HS-N-R3-D3.5-O
Elevation: 8,600
Aspect: NE
Coordinates: 45.8926, -110.9620
Caught: 0 ; Buried: 0

Saw this today while skiing. This crown is on a northeast aspect at about 8600 feet. Crown height 6-8 feet. It is mid path in the Great One. It seems to have naturally avalanched on Sunday during the storm, without a cornice trigger, after the wind event. All I can get here is that the slope was overloaded from storm snow, on top of a recently overgrown hard slab. Looks like it initiated higher up and pulled out much deeper below. Definitely a large hard slab avalanche. HS-N-R3-D3.5. Debris made it to the trees in the historic path. Otherwise, northeast aspects are loaded above 8500 feet, and I saw about 14 inches of new at 8000 feet. No loading during the day today. 


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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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Cooke City
Town Hill
Town Hill Avalanche, Cooke City
Incident details include images
Town Hill
SS-NC-R2-D2
Elevation: 8,400
Aspect: SE
Coordinates: 45.0256, -109.9370
Caught: 0 ; Buried: 0

The Nose of Town Hill avalanched on Feb. 1 due to the strong SWerly winds and looked to be triggered by a cornice fall (estimated 2-3' crown, about 75-100' wide. 


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Northern Madison
Cedar Mtn.
Natural avalanche on Cedar Mtn.
Incident details include images
Cedar Mtn.
HS-NCu-R2-D3
Aspect: E
Coordinates: 45.2268, -111.5120
Caught: 0 ; Buried: 0

From Big Sky Ski Patrol: "Also saw a large slide on one of the far ridges of Cedar that was not there yesterday and appears to be cornice triggered."


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Cooke City
Woody Ridge
Wind Slabs on Woody Ridge
Incident details include images
Woody Ridge
SS-N-R1-D1.5-I
Elevation: 9,400
Aspect: E
Coordinates: 44.9937, -109.9160
Caught: 0 ; Buried: 0

Winds Friday night transported snow creating fresh drifts that avalanched naturally over the weekend. We observed two wind slabs that released naturally on the east side of Woody Ridge both appear to be 2-3' deep and 50' wide. 


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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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Northern Gallatin
Hyalite - main fork
Natural avalanche in wind-loaded snow near Mt Bole, Hyalite
Incident details include images
Hyalite - main fork
SS-N-R2-D2-I
Aspect: SE
Coordinates: 45.4472, -110.9620
Caught: 0 ; Buried: 0

From an observation: "We were up on the ridge off Palace Butte and saw this recent natural released slide. Crown was big in spots. Must have happened sometime over night or in the morning (1/29 or 1/30) perhaps from the recent wind loading. East, southeast facing, on the peak north of MT Bole."


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Northern Madison
Fan Mountain
Large Natural Avalanche on Fan Mtn.
Fan Mountain
G
Aspect: N
Coordinates: 45.2981, -111.5240
Caught: 0 ; Buried: 0

From email: "There was a large avalanche on the north face of Fan.  It is not on the NE Face that everyone skis, but out to the west of the north couloir where there is a major ridge off the summit.  North aspect, estimated at over 1K ft. wide, to the ground with a deep crown.  Likely triggered by cornice fall."


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Cooke City
COOKE CITY
Thin natural wind slabs in Cooke City
Incident details include images
COOKE CITY
SS-N-R1-D1
Aspect: E
Coordinates: 45.0202, -109.9380
Caught: 0 ; Buried: 0

From email (1/30/2020): "2 natural avalanches that ran last night, just west of Cooke City.  Both slides were on easterly aspects around 9500'."


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Cooke City
Lulu Pass
Human triggered wind slab on Lulu
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Lulu Pass
SS-AFr-R2-D2-S
Elevation: 10,000
Aspect: S
Coordinates: 45.0709, -109.9580
Caught: 0 ; Buried: 0

We triggered this avalanche of wind-drifted snow as we approached very carefully from a low angle slope above, on 1/30/2020. This was near Lulu Pass outside Cooke City on a south facing slope at 10,000'. It broke within recently drifted snow, but these slabs could be enough weight to break deeper and wider on sugary layers deep in the snowpack. I initially approached where the cornice was a little steeper (no overhang though), and then I got that funny feeling and backed off and went to safer feeling spot with the intention to dig at the top of the slope. It broke within the recent snow/wind load, and did not step down. It was about 100’ wide x 70’ long x 2-3’ deep.


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Northern Gallatin
Mt Blackmore
Small Wind Slab on Mt. Blackmore
Incident details include images
Mt Blackmore
SS-AS-R1-D1-I
Elevation: 9,200
Coordinates: 45.4439, -110.9970
Caught: 0 ; Buried: 0

Snow picked up at Mt. Blackmore with calm to light winds. Someone up there before us pulled out a small wind loaded pocket on the face leaving the basin.


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Bridger Range
Naya Nuki Bowl
Natural Avalanche on Naya Nuki
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Naya Nuki Bowl
HS-N-R2-D2.5-O
Coordinates: 45.8883, -110.9590
Caught: 0 ; Buried: 0

Avalanche crown visible near the top of Naya Nuki Peak in the Northern Bridgers. Estimated max crown depth of 10 ft, approximately 200 ft wide. Photo taken Jan 29th, 2020. Several inches of snow were on the debris, avalanche likely occurred on Monday, Jan 27th. 


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Northern Madison
Big Sky Resort
Explosive triggered Deep Slab Avalanche at Big Sky
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Big Sky Resort
HS-ABc-R4-D4
Coordinates: 45.2760, -111.4360
Caught: 0 ; Buried: 0

A deep slab avalanche was triggered using explosives on 1/24/2020 in the North Summit Snowfield at Big Sky Resort. 

From email: "The Whale came out close to 10’ deep that tapered to 3’ on the skiers right edge...  It broke on basal facets, thin layer, 1F hard at crown (!) with very hard snow above and below the layer that failed ....  It is likely that the layer that failed had some different characteristics lower in the path that avalanched away- possibly less hard."


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Northern Gallatin
Alex Lowe Peak
Natural on Alex Lowe peak
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Alex Lowe Peak
N-R2-D2-O
Elevation: 9,900
Aspect: N
Coordinates: 45.4272, -111.0140
Caught: 0 ; Buried: 0

A skier saw this slide from the top of Mt. Blackmore on 1/25/2020.


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Bridger Range
Ross Peak
Large Collapse near Ross Peak
Ross Peak
Coordinates: 45.8586, -110.9560
Caught: 0 ; Buried: 0

From email: "Went out to Ross Peak with some friends today, and we saw some alarming signs. Snowpack out there was really shallow, similar to the approach to the Throne. We got to the first major clearing at about 7500', which tops out at about 36 degrees at the steepest part. We opted to tuck back in to the trees to try to find a lower-angle route around the slope, but there wasn't really a better option. It is a really short (~50') but wide (~500') slope, and we decided it would be reasonable to cross it one at a time. I was setting the skin track and got a big collapse that scared the shit out of me. For some reason it didn't slide, but I measured a few angles and the area that collapsed was definitely at 34-36 degrees. Probably collapsed an area about 100' across. After I had a chance to clean out my long johns, we turned around and skied back down the skin track."


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Cooke City
Wolverine Peak
Natural Avalanche Wolverine Peak
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Wolverine Peak
HS-N-R3-D2.5-O
Elevation: 10,000
Aspect: SW
Coordinates: 45.0530, -110.0100
Caught: 0 ; Buried: 0

A large natural avalanche observed on the southwest face of Wolverine Peak. Observed 1/20/2020. Photo: D. Wycoff


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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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Cooke City
Meridian Peak
Natural Avalanche Meridian Peak
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Meridian Peak
HS-NO-R3-D2.5-O
Elevation: 9,800
Aspect: NW
Coordinates: 45.0270, -110.0030
Caught: 0 ; Buried: 0

A large natural avalanche observed on the northwest face of Median Peak on 1/20/2020. Photo: D. Wycoff


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Northern Madison
McAtee Basin
Snowmobile Triggered Avalanche McAtee Basin
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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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Southern Madison
Taylor Fork
Collapsing at Taylor Fork
Taylor Fork
Coordinates: 45.0607, -111.2720
Caught: 0 ; Buried: 0

Skied a lap at 44.96854,-111.272761. Two big collapses on the skin back up, and frequent shooting cracks. We were very glad to be skiing low angles.


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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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Lionhead Range
Lionhead Ridge
Natural cornice triggered Lionhead Ridge
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Lionhead Ridge
HS-NC-R2-D2-O
Elevation: 8,900
Aspect: NE
Coordinates: 44.7121, -111.3130
Caught: 0 ; Buried: 0

With only 3" of new snow overnight, a cornice triggered a large avalanche at Lionhead early this morning. It broke 3 to 4 feet deep and propagated on a buried weak layer. This is the only stability test we need today, human triggered avalanches possible and the management strategy is to avoid steep slopes or be clear about your risk tolerance if you are poking into avalanche terrain.


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Bridger Range
Truman Gulch
Collapses and Whumphs west side Bridgers
Truman Gulch
Aspect: W
Coordinates: 45.8535, -110.9700
Caught: 0 ; Buried: 0

From obs: "Took a tour down the ridge dividing Truman and Jones creek Sunday.Snow varied from 12 inches of facets topped with a crust to big solid wind deposits sitting on basal facets to 2 feet of fist and 4 finger snow over a 1 finger crust over more facets. Quite a bit of cracking and whoomphing on westerly and wnw aspects. I avoided the large paths altogether and stayed on the ridge."


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Cooke City
Hayden Creek
Natural Deep Slab Avalanche Hayden Headwall
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Hayden Creek
HS-N-R3-D2.5-O
Elevation: 10,200
Aspect: N
Coordinates: 44.9952, -109.9080
Caught: 0 ; Buried: 0

Spotted the crown on our way down from Ripcurl yesterday, we got a closer look today when we toured into High Hayden. N aspect 10200' 


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Bridger Range
Texas Meadow
Skier triggered north of Bridger
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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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