Avalanche Activity

From obs: "Intentionally triggered on a ski cut. Broke about 1 foot deep and 10 feet wide, ran on a hard compact surface below the soft wind slab." 

Big Sky Ski Patrol triggered a deep slide in the Big Couloir during avalanche mitigation work on 11/28/24: "Summit north peeled the cornice way back to the ridge and took out the upper hanging snowfield before crashing into the Couloir, leaving a 5-6’ tall crown in the chute above the dogleg."

Dave and I toured into Blackmore basin today and skinned up the SE shoulder to the ridge. As we entered the basin, we immediately noticed several natural loose snow avalanches (R1 D1) in steep rocky sections of the direct E face. These looked to have occurred in the last 12 hours, and though they would not have buried someone, they would have strained one through some nasty trees and cliffs.

Big Sky Ski Patrol triggered this avalanche during mitigation work in The Wave on 11/26/24... "2-3' deep on an ice crust just above the ground with a 2# shot in the Upper rodeo. Volume was limited as most of the snow was loaded just underneath the cornice, but still produced a sizeable size 2... Other paths in the Lenin region ran meaty wind slabs, full track with no significant step downs." Photo: BSSP

From email: "Northerly facing terrain harbors October snow, which has faceted. It is holding up plenty of dense snow and wind slab from the quite snowy and windy November. It was unable to hold the additional weight of a human trigger, and two pockets failed at the ground, which produced avalanches. Crown height maxed at 2’. Notably, where it did not avalanche, the failure propagated hundreds of feet down the ridge. It is a good data point- northerly aspects near tree line have potential instability."

Driving up Bridger Canyon this morning, we noted several natural avalanches in wind loaded terrain on Saddle Peak, the Football Field, and in Mundy’s Bowl. All The avalanches seems to be a similar wind slab problem. They broke just below the cornice line. From a distance and considering yesterday’s new snow, I would guess a foot deep or so (R2, D2, I)

Wind was ripping on the ridge and creating hard wind slabs 3-6” in depth. Without much new snow to transport they weren’t very large or widespread, but we got cracking and propagation on a steeper terrain feature (Hidden) near the ridge that led to us skiing a different line. The slab development was also found in isolated areas further down from the ridge in cross loaded gullies, but slabs were isolated to breaking at the skis. 

Localized collapsing and cracking yesterday on the upper slopes of Mt. Henderson, SW aspects.  HS ranged from about 30-75cms. 

From obs: "With the inversion and warmer temperatures yesterday, we (group of 3) discovered a super saturated, cohesive snowpack in Hyalite on the approach to High Fidelity. On the first pitch, I narrowly avoided a point release wet loose, probably around D1-1.5. After this we decided to bail. On the rappel, my partner narrowly avoided another wet loose, which he estimated to be D1.5 and deep enough to bury a person past their chest. The sun was not out but the mountains were shedding and there was evidence of warming and wind, because the trees had no snow on them. We were able to make ~2.5 feet in diameter “cinnamon rolls” by rolling a snowball downhill. If you’re going to any of the more exposed climbs in Hyalite, be very mindful of overhead hazards and wet loose problems which you would not expect this time of year." 

Skiers triggered several very thin avalanches in the northern Bridger Range on 11/21/24. They broke only a couple inches deep on windloaded slopes, mostly in north facing couloirs. 

Party of three made our way into Beehive Basin up to near the bottom of 4th of July Couloir. Noted strong winds blowing from the south southwest (up the canyon) Saw shooting cracks up to 8 feet out skinning up a boulder pile on a east facing aspect, (picture my friend took). Snowpack still to shallow to confidently ski any of the upper couloirs. Further down in the canyon on the short grassier slopes snowpack was reasonably dense and stable with a weak crust layer under 8-10 inches of the light fluffy stuff, snow depth up to 2 feet in select spots. Friend reported hearing one small whumph breaking trail up to the ridge on a convex roll. Skied out the entire slope with 10ish other people and didn't see any other signs of instability.

A small avalanche released in the northern bridger range on Sunday.

We skied hidden gully that had small storm slabs that propagated at our ski tips and only ~3inches in depth. 

On 20241107 I observed a small natural avalanche from the top of the PK lift at Bridger Bowl. The slide occurred  near the Slushman’s lift on a NNE aspect. It started as a small release in the upper start zone and entrained much of the snow in the couloir down to the ground. L-N-D1.5- G. 

Avalanche occurred after the start zone had come into the sun for a few minutes. The rest of the path was in the shade.

Wind speed at 11am 24mph gusting to 28mph on Bridger Ridge. Sky Clear. Temp 26F.

It was a relatively small slide but had enough power to carry a skier or rider through some very nasty terrain. Similar aspect and elevation to the Super Couloir slide. 

From obs: "I made it up to an old crown in a north-facing chute around Fairy Lake at around 9400 ft; it broke the night of 11/6 or the morning of 11/7. It looked like a wind slab that broke on a rotten layer of facets intermixed with scree. Found facets to be fairly widespread through the bottom of the snowpack on the north-facing slopes and surface hoar on most nonsolar slopes." 

From IG message: "Hey the post of super jogged my memory to send you this, a friend and I had whumpfing and cracks while skinning up the trees in the apron yesterday [11/6], we dug a pit and got an ect 4 collapse against the rocks. We were about halfway up the apron when we took this."

From obs 11/6/24: "Saw debris from several small natural avalanches below the ridge on an east aspect south of saddle peak while driving up to bridger. Most looked like point releases but there was one that might have been a small slab. Unsure because the light wasn't right to tell if there was a crown.

We stayed low but found a pretty uniform snowpack other than a couple of spots with sun crusts.

There was also tons of snow blowing over the ridge when we left around 3pm."

From IG Message: “Hey guys - my partner broke off a small avalanche in super couloir today… broke full depth across half the couloir, 2-3’ deep/20’ wide and looked like it ran around 500’. No one was caught. He might message you with pictures too but here’s a video from the top”

From IG Message: “Skier triggered Pocket in super couloir. Wasn't very unexpected, the skiers left side felt a little slabbier than the skiers right and tried to stay off it but got blinded by a sick face shot. Triggered going over a sharky rock spot, not very fast moving and easy to ski out of. Snow depth was 2-2.5 feet”

Avalanche observed on Chico Baldy above Mill Creek in Paradise Valley.  East aspect at about 9400'. Possibly a wind slab but hard to tell

Triggered a small wind slab:

-9600'

-N aspect on the NW ridge of Sphinx Mountain 

-Strong SW wind

-Noticed other small crowns, likely triggered from another party traversing the north-facing bowl at similar elevations