Avalanche Activity

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

Bill Whittle of Cooke City SAR reported that one sledder triggered a slide in a terrain trap to the northwest of Lulu Pass (45.06703, -109.97180). It caught him, but he was not buried. It only buried the tail of his sled. He hit his "SPOT" rescue beacon because he was stuck. A little while later a rider on a rental sled was unable to ascend Daisy Pass to return to town. As he was walking up the pass and others were retrieving his sled, a 2 foot deep (est.) natural slide released on the northeast aspect of Crown Butte that missed them.

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

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


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Southern Gallatin
Specimen Creek
Collapses in s. Gallatin
Specimen Creek
Elevation: 8,300
Aspect: S
Coordinates: 45.0265, -111.0480
Caught: 0 ; Buried: 0

From e-mail: "Skied up to 8300 feet on Meldrum Mountain until I succumbed to the deadfall and turned around. Poor structure with facets at the ground and low coverage. Collapsing on southerly aspects where there was enough snow. Northerly aspects were unsupportable."


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Bridger Range
Bridger Bowl
Bridger patrol triggered large slides on heavily wind loaded slopes
Incident details include images
Bridger Bowl
HS-ACc-R2-D3-O
Elevation: 8,500
Aspect: E
Coordinates: 45.8156, -110.9230
Caught: 0 ; Buried: 0

Ski patrol triggered two large hard slab avalanches, one in Slushman's Ravine and the other in Mundy's Bowl, by knocking large cornices down on the slope. One was 4' deep, AC-HS-R2-D3-O, ran 1150' vertical. The other was 2.5' deep, AC-HS-R2-D2-O, ran 650' vertical. This was their first control in this area for the season, so the snowpack is similar to backcountry.


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Cooke City
Mineral Mountain
Natural slide on Mineral Mountain
Incident details include images
Mineral Mountain
Coordinates: 45.0303, -109.9980
Caught: 0 ; Buried: 0

From an email:

"Chris and I toured up the East Ridge of Mineral today and dug a pit on a NE aspect around 9000'. HS 75 cm, mostly facets with the exception of the new snow. ECTX. We found more of a windslab on some more exposed features although it wasn't reactive for us and we saw no natural avalanches with the exception of a small slide in the couloir skier's left of the summit of Meridian. We were still a ways away but it appeared to have run on the old/new snow interface."


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Northern Madison
Beehive Basin
Small intentionally triggered wind slab in Beehive Basin
Incident details include images
Beehive Basin
SS-ASc-R1-D1.5-I
Elevation: 9,000
Aspect: SW
Coordinates: 45.3420, -111.3870
Caught: 0 ; Buried: 0

From Obs.: "New snow from 24 hours ago blew around the ridge tops from 11pm last night until 7am this morning ~30mph. This soft 4 finger slab was about 6”-7” deep and broke on a convex roll... We were assessing the terrain carefully and expected this result."


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Northern Gallatin
Hyalite - main fork
Natural and human triggered wind slab avalanches in Hyalite
Incident details include images
Hyalite - main fork
SS
Coordinates: 45.4472, -110.9620
Caught: 0 ; Buried: 0

Observations from Hyalite today:

1. When approaching the base of Mt. Blackmore this morning at roughly 8:45am we observed strong swirling winds at higher elevations (summit of Blackmore and the Elephant/Blackmore Saddle). The winds we observed were primarily loading snow onto E and SE facing aspects. Furthermore, we witnessed four naturally triggered avalanches over a twenty minute span. All slides appeared to be D1/D2 on E and SE aspects and, seemingly, restricted to the newly loaded snow.

2. My partner and I climbed Zach Attack today. We intentionally triggered numerous size 1 wind slabs in the gully approaching the climb, which has slopes up to 35 degrees. These slabs were between 5 and 15 cm thick, up to 5m wide, 4F in hardness, touchy, and failed on lower density new snow. Although none of them ran more than 20m in this terrain, it would be a different story on steeper slopes, and if you were in an exposed position they had enough mass to push you around. Strong down and cross-slope winds formed these slabs at and below treeline, while the more alpine terrain of the climb itself was scoured.

3. Skied up in the main drainage of Hyalite today. Triggered some small wind slabs and propagating cracks. We backed off our main objective (a north facing couloir) because of these red flags and multiple crown lines on the same aspect and elevation.

 

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Bridger Range
Saddle Peak
Natural and human triggered wind slabs in the Bridger Range
Incident details include images
Saddle Peak
SS-N-D2
Aspect: E
Coordinates: 45.7943, -110.9360
Caught: 0 ; Buried: 0
From an email:
"I toured up Bridger today... We found reactive windslabs at the ridgeline. On the drive up we observed a few small avalanches in Mundies Bowl and a larger (D2) slide just north of Saddle’s north summit. All appeared to be windslabs that released at the ridgeline. We dug a pit a few hundred feet below the ridge above the entrance to 2 Way and Stuper. I’ve attached a photo of this, as well as of windslabs at the ridgeline and one of the flank of the slide on Saddle"

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Bridger Range
Bridger Peak
Skier triggered loose snow and natural wind slabs at Bridger
Bridger Peak
L-R1-D1.5
Elevation: 8,300
Aspect: E
Coordinates: 45.7701, -110.9400
Caught: 0 ; Buried: 0

Skiers saw natural soft slabs that broke below the cornice along the ridge near Slushman's lift.

Another group reported: "I spotted a buddy skiing the lower nose and he started a couple of slow moving sluffs, well in his wake... We did see a recent point release in that zone, from a ski track, that ran over 200 feet in steep terrain."


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Lionhead Range
Lionhead Ridge
Widespread Collapsing at Lionhead
Lionhead Ridge
SS-AS-O
Elevation: 8,500
Aspect: NE
Coordinates: 44.7145, -111.3180
Caught: 0 ; Buried: 0

From obs.: "8500 feet Northeast aspect. Extended column test ECTP 9 Failed near the ground on prestorm facets. 60 cm total snow depth. Widespread collapsing in open terrain."


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Northern Madison
Beehive Basin
Skier triggered dry loose at Beehive
Incident details include images
Incident details contain video
Beehive Basin
L-ASc-R1-D1-O
Elevation: 9,000
Aspect: W
Coordinates: 45.3407, -111.3910
Caught: 0 ; Buried: 0

We were able to trigger dry loose avalanche in the 3-5" of new snow that ran on firm underlying crusts.


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Northern Gallatin
Overlook Mountain
Shooting cracks in windslabs, Hyalite
Incident details include images
Overlook Mountain
Coordinates: 45.4050, -110.9420
Caught: 0 ; Buried: 0

From an email:

"At about 9,000ft on the northern aspect of Overlook mtn we dug a pit to the ground (90cm) and got ECTX and very stable results. We found the basal faucets to be quite rounded except for some large ones growing off rocks. About 500ft higher we found a pervasive wind slab that stretched across the face. We got some large shooting cracks while skinning and ended up turning around. Picture is attached. Before the wind picked up we found surface hoar almost 3/4 of an inch deep!


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Out of Advisory Area
Large avalanches in Absaroka - Outside Advisory area
Incident details include images
HS-N-R2-D2.5-U
Elevation: 10,000
Aspect: NE
Caught: 0 ; Buried: 0

Sometime last week (11/20-11/22) these large avalanches occurred on heavily wind loaded northeast facing slopes in the Absaroka. The snowpack there is thin and faceted, similar to the southern ranges and mountains near West Yellowstone. Photo: B. VandenBos


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Bridger Range
Bridger Bowl
Small new snow avalanches at Bridger
Incident details include images
Bridger Bowl
SS-N-R1-D1.5-I
Elevation: 8,500
Coordinates: 45.8156, -110.9230
Caught: 0 ; Buried: 0

Thursday, November 21:

1. "I observed 2 natural avalanches on the slopes between the Apron and Ramp. No ski tracks in those areas. I thought I took a picture but didn’t. Looks like they both started in the rock bands below the ridge. One was small and the other was considerably larger. Hard to know if they ran today or yesterday. Looked like it was just new snow. Pretty much east aspect."

2. "Toured up to the ridge at Bridger today and traversed into Bridger Gully. At around 8,000' in the trees above the most prominent snowfield, my partner and I observed very small dry sluffs confined to the new snow. Bellow Bridger Gully, my partner was able to release a slide while traversing through rocks above his intended line. This was on an east-southeast aspect at 7,500'. Snow just a few degrees more to the east was dryer. The snowpack nearby thinned greatly on the east-southeast aspect.

Wednesday, November 20:

1. " Noted some activity (D1-D2) isolated to the new snow around rock features and ridgetops that were wind-affected.  Our pit revealed a weakening and thin snowpack due to the drier weather, however, the facet growth at the ground has remained fairly slow and has maintained moisture."


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Northern Gallatin
Flanders Creek
Rivers of loose snow avalanches in Flanders Drainage
Flanders Creek
L-N-I
Elevation: 9,500
Aspect: E
Coordinates: 45.4402, -110.9310
Caught: 0 ; Buried: 0

From Doug Chabot:

I went ice climbing in Flanders and got hit with a graupel storm (0830) which avalanched off the climbs on east-facing slopes for over an hour. It was pretty spectacular and we found knee deep graupel (small, ball-bearing like grains) 200 vertical feet from the bottom of the cliffs. The climbs that we saw this on were Big Sleep, Bobo Like and Killer Pillar. The snow appears to be sliding on a razor thin ice crust under the 3" of new snow that fell last night, which was dense (estimated 15%).

I dug a hand pit to the ground and found 2' of mostly solid snow (no obvious facets) with a couple ice crusts in the upper third. A CT cut with a ski pole yielded no fractures. Elevation 8,000', east aspect.


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Northern Madison
Beehive Basin
Small wet avalanche in Beehive
Incident details include images
Beehive Basin
N-R0-D1-G
Elevation: 8,900
Aspect: SW
Coordinates: 45.3407, -111.3910
Caught: 0 ; Buried: 0

From an email: "I observed a wet loose avalanche that most likely occurred yesterday afternoon. Occurred at an elevation of 8,900' on a WSW aspect, along the runout of a chute sometimes referred to as "the gem". It wasn't very large, but it ripped out to the ground in sections and looked like it could do some damage if caught off guard. I assessed the snowpack next to the small slide, and found a snowpack of only 30 cm composed of facets from 0-14 cm above the ground (F hardness), a crust of large bonded grains from 14-16 cm above the ground, small facets / rounding facets from 16-23 cm above the ground, a rain crust from 23-27 cm that blended into wet snow on the surface becoming slabby in the afternoon sun."


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

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


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Bridger Range
Bridger Bowl
Cracking Wind Slabs at Bridger
Incident details include images
Bridger Bowl
Coordinates: 45.8156, -110.9230
Caught: 0 ; Buried: 0

Two parties reported shooting crack at Bridger Bowl today (11/11/2019).

"While skinning up to the top of Powder Park lift at Bridger, we had roughly 15' cracks propagate on an E/SE aspect. A snowpit showed roughly 8" of wind slab above a few inches of facets, on top of last week's rain crust."


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Northern Gallatin
Mt Blackmore
Wind Slab avalanche on Mt. Blackmore
Mt Blackmore
Coordinates: 45.4444, -111.0040
Caught: 0 ; Buried: 0

Natural wind slab avalanche on the N face of Mount Blackmore on 11/10/2019.

From email: "Noted recent activity on the N face which likely happened yesterday during the storm; upper half of the avalanche and crown had been scoured by wind, but the toe of the debris was still visible and had traveled quite far"


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Bridger Range
Bridger Bowl
Wet loose at Bridger
Incident details include images
Bridger Bowl
WL-N-R1-D1
Coordinates: 45.8156, -110.9230
Caught: 0 ; Buried: 0

Several small wet loose avalanches were observed at Bridger Bowl on 11/5. 


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Northern Gallatin
Divide Peak
Cornice triggered slab in Hyalite
Incident details include images
Divide Peak
SS-NC-R2-D1.5-I
Elevation: 9,500
Aspect: SE
Coordinates: 45.4029, -110.9760
Caught: 0 ; Buried: 0
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Northern Gallatin
Hyalite - main fork
Collapsing of a wind slab in Hyalite
Hyalite - main fork
Aspect: W
Coordinates: 45.4472, -110.9620
Caught: 0 ; Buried: 0

"I postholed up to Zach Attack today and dug a pit in the gully a few hundred feet below the route. We found about a meter of snow on the ground, the upper 65 cm being generally unconsolidated (fist-4F hardness) snow largely transported by the wind. Below that was a 5-10 cm MFcr on top of small (1-2 mm) basal facets. Higher up in the gully we found a few isolated winds slabs, and on the way my back down one of my partners felt a wumph as we crossed above a leeward convexity."


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Northern Madison
Beehive Basin
Skier triggered small wind slabs in Beehive
Incident details include images
Beehive Basin
SS-ASc-R1-D1.5-S
Elevation: 9,500
Coordinates: 45.3407, -111.3910
Caught: 0 ; Buried: 0

From e-mail: "Skied in the the beehive area today. Triggered some small wind slabs that were sliding on a crust. 

E aspect 9,100': Triggered from a stomping a small cornice, which landed on a steep slope below and popped a small wind slab.

NE aspect 10,000': Triggered while skiing through a choke point. This one was thin but ran down slope quite a ways because the terrain was steeper. It was easy to avoid by skiing off to the right, since the gully was just cross loaded a bit on the left.

SE aspect 9,800': The third was just some propagating cracks. The slope angle wasn't quite steep enough to slide here.

These instabilities appeared to be confined to areas of dense wind drifted snow on top of a crust layer and did not appear to be wide spread."


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Northern Gallatin
Mt Blackmore
Natural wind slabs and dry loose avalanches Mt. Blackmore
Incident details include images
Mt Blackmore
SS-N-R1-D1-S
Elevation: 9,500
Coordinates: 45.4444, -111.0040
Caught: 0 ; Buried: 0

From obs., "Activity I observed was restricted to the new snow. A fair bit of loose snow....  Skiers on the E bowl of Blackmore triggered some D1 dry sluffage, running on a crust beneath the new snow.... No slab activity observed until the wind started pushing more snow around this afternoon. I watched a small (D1) wind slab build and fail as the wind picked up near the Blackmore/Elephant saddle (happened just before 2pm). Slab couldn't have been much thicker than 15cm, broke 30-40m wide. These slabs were building rapidly..."


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Northern Gallatin
Mt Blackmore
Small wind slab triggered in Hyalite
Incident details include images
Incident details contain video
Mt Blackmore
SS-ASc-R0-D1-I
Aspect: S
Coordinates: 45.4444, -111.0040
Caught: 0 ; Buried: 0

Dave Zinn triggered a small wind slab off the ridge on Mt. Blackmore.


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Bridger Range
Bridger Bowl
Natural avalanches north of Bridger
Incident details include images
Bridger Bowl
SS-N-R2-D1.5-I
Elevation: 8,400
Aspect: NE
Coordinates: 45.8156, -110.9230
Caught: 0 ; Buried: 0
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Bridger Range
Bridger Bowl
Shooting Cracks at Bridger Bowl
Incident details include images
Bridger Bowl
Aspect: N
Coordinates: 45.8156, -110.9230
Caught: 0 ; Buried: 0

Went for a midday skin up Thunder Road during the maelstrom today. It was blowing gale force, mostly from the south but seemingly from all directions at times...here’s a pic from a north facing slope below Thunder Road, about midway up PK. We saw a few more shooting cracks in the flats below the top of PK, and the surface wind slab where this photo was taken was ~10 cm.
 


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

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

From instagram:

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

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

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

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


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Northern Gallatin
Hyalite - main fork
Natural avalanches in Hyalite
Incident details include images
Hyalite - main fork
SS-N-R1-D1.5-I
Coordinates: 45.4472, -110.9620
Caught: 0 ; Buried: 0

A skier in Hyalite wrote, "Natural activity that I observed was failing at new/old interface and (generally) occurred in predictable, wind loaded locations near ridge lines. The one exception is the avalanche with the freshest debris; looks like it failed right at the end of the storm in a somewhat sheltered, mid-slope location." Photo: B. VandenBos


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Bridger Range
Bridger Bowl
Natural and skier triggered new snow/wind slabs at Bridger
Incident details include images
Bridger Bowl
SS-N-R1-D1.5-S
Elevation: 8,000
Coordinates: 45.8156, -110.9230
Caught: 0 ; Buried: 0

Gusty North wind and moderate snowfall created sensitive drifts. From obs. "Some moved while I was skinning up, some slid naturally (hidden/[Apron area]) mostly recent wind deposition.


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Bridger Range
Bridger Bowl
Small avalanches at Bridger
Incident details include images
Bridger Bowl
SS-AS-R1-D1
Coordinates: 45.8156, -110.9230
Caught: 0 ; Buried: 0

Small storm slabs triggered at Bridger Bowl on 10/26. From email: "slab formation appeared isolated to leeward sides of midslope terrain features and rollovers as well as at ridgetops". 


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Northern Gallatin
Mt Blackmore
Small Wind Slabs on Mt Blackmore
Mt Blackmore
SS-AS-R1-D1
Aspect: E
Coordinates: 45.4444, -111.0040
Caught: 0 ; Buried: 0

A skier reported lots of wind transport and triggering several thin wind slabs on the east face of Mt. Blackmore, in the northern Gallatin Range (10/25).


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Southern Madison
Taylor Fork
Avalanches in Taylor Fork
Incident details include images
Taylor Fork
HS-R2-D2-O
Elevation: 10,000
Coordinates: 45.0607, -111.2720
Caught: 0 ; Buried: 0

From email: "Found this large slide just north or Imp today [10/25]. Right around 10k, N-NE aspect, crowns spanned estimated 800-1,000' and ranged from ~2-10' thick. Appeared to activate by both a weak layer near the ground and a mid-pack interface. Lower interface was pencil hard, variably icy melt freeze crust of some sort, with 10-20 cms of 2-3mm facets underneath. Didn't get a good handle on the mid-pack interface, mostly assumed its presence based on shallower crowns.

Also saw several other crowns, at similar and slightly lower elevations on similar aspects to the SW of above described slide. Other crowns appeared thinner and less wide."


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Bridger Range
Saddle Peak
Cornice Collapse-Saddle Peak
Incident details include images
Saddle Peak
L-NC-R1-D2
Elevation: 9,100
Coordinates: 45.7943, -110.9360
Caught: 0 ; Buried: 0

Skiers noted recent activity on Saddle isolated to fresh cornice fall and loose snow sluffing. The snow still available for transport was isolated to upper elevations, as mid/lower elevations the snowpack was wet and warm.


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Northern Gallatin
Hyalite - main fork
Small avalanche in Hyalite
Incident details include images
Hyalite - main fork
SS-AFu-R1-D1
Coordinates: 45.4327, -110.9750
Caught: 0 ; Buried: 0

Ice climbers triggered a small avalanche while approaching the Twin Falls ice climb in Hyalite Canyon on Sunday (10/20).


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Northern Gallatin
Hyalite Peak
Wind slab and dry loose in Hyalite
Incident details include images
Hyalite Peak
HS-N-R2-D1.5-O
Elevation: 9,650
Aspect: NE
Coordinates: 45.3810, -110.9610
Caught: 0 ; Buried: 0
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Northern Madison
Sphinx Mountain
Whumph on The Sphinx
Incident details include images
Sphinx Mountain
AF-O
Elevation: 9,000
Aspect: N
Coordinates: 45.1582, -111.4770
Caught: 0 ; Buried: 0

From e-mail on Saturday 10/5, climbers on the Sphinx found these conditions: "We found a lot of snow on the Sphinx today following heavy precip since Sam’s report two days ago [see photo]. 3-5 cm in the parking lot, 20 cm at the Sphinx-Helmet col. Moderate SW winds had created drifts almost a meter deep in places on the traverse to the ice routes on the north face. I backed off after a whumph on a particularly exposed section of the traverse. We tried different ledge systems above and below the normal approach route but found similar snow conditions throughout."

Photo: From 10/3 prior to 8-10" new snow, "No snow hazard of much concern on the approach. However, a quick hasty pit in an isolated wind pocket revealed a CT1 on this layer.  ice axe is to the ground."


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Bridger Range
Fairy Lake
Small wind slab near Fairy Lake
Incident details include images
Fairy Lake
SS-AS-R1-D1-S
Elevation: 9,000
Coordinates: 45.9043, -110.9580
Caught: 0 ; Buried: 0

From e-mail: "The only places one could ski were wind pockets blown into the limestone fin features that in places were well over a foot. These spots were also where the snow was weirdest/posed any sort of avalanche hazard as you pretty much had to find a wind slab in order to ski anything! One group reported triggering a slab in one of these spots, but vis was too poor to see."


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Out of Advisory Area
Pine Creek
Wet Slides across Pine Creek trail
Incident details include images
Pine Creek
WL-N-R2-D1.5
Elevation: 9,000
Aspect: SW
Coordinates: 45.4900, -110.4950
Caught: 0 ; Buried: 0

From e-mail: "A couple wet slides buried the trail up to 4’deep on a sw facing slope approaching 9000’ in elevation. Probably set off yesterday with clearing skies. Snow depth was about 14” at Jewel Lake."


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