Snow Observations List

Avalanches on Henderson Mountain near Cooke City were reported via instagram on 11/9/2023. Estimating they occurred a day earlier. 

From message: "on Henderson in Cooke just above the lulu trail. It was surprising to see so much activity"

Skier triggered windslab in the Great One off of Naya Nuki peak, skier was carried 15-20ft before arresting. Slide was triggered roughly halfway down the couloir where the right wall dips away exposing the snow to wind. Hard consolidated snow over facets, roughly 1-1.5 ft thick, ran about 50-100 ft before pouring over the cliff faces below. North- northeast aspect. 

Snowpit attached from today:  SW aspect, 9800', HS: 57.

Surfy/ supportable, good early season turns.  Though some signifiant collapsing experienced while trail breaking- on buried SH that formed on Halloween.

No avalanche activity to report.

A hiker at Bridger Bowl noticed a small, loose snow avalanche near the Apron. Noting that it was a, "Good reminder as to how little snow is required to have an avalanche!"

Went for a skin up to Hyalite Peak yesterday to check out snow conditions. We found about 8-12 inches of new snow sitting on a base at Hyalite Lake. We saw no signs of instability in the area. Small cornices were observed on the Hyalite saddle, and a hit or miss 1 inch wind slab directly below the ridge. 

Was out alpine climbing today and observed the north face of Blackmore had slid already.

From IG: “Pine creek today, some small wind slabs and a full depth wet slide off black mountain”

Three clear storm layers and wind effect piling up larger drifts. Snow height at 9k ft averaged 85-90cm. The rain layer in the center of the pack creating a sheer surface that with more load could trigger the third storm layer.

Sent a couple emails to mtavalanche.com with pics of a R3.9D11 that just missed me by inches last year. Just a heads up about Cornices and slabs 

From email: “These pics are from last June 10-11, after the pass reopened on Friday. I was skiing the Gardner headwall at 5:30, solo, when this monster released. Yah. The initial cornice collapse triggered and entrained a secondary slab of varying thickness whose crown is seen in one of the photos.”

Snowmobilers saw a recent wet slab on the northeast face of Henderson Mtn. on May 20, 2023. Video attached.

Wet slab avalanche on Hollow Top Mtn., Tobacco Roots 

ENE facing slope at 8,800’

On May 14 and 15 we saw crowns and debris of wet slabs that ran naturally over the past couple weeks.

Scotch Bonnet, S aspect, 9800'; Sheep Mtn. SW aspect, 9800'; Crown Butte, SE aspect, 10000'.

Hard to say exactly when they all occurred. The slides on Scotch Bonnet and Sheep appeared slightly fresher, but could have been a week old.

Skier triggered slide in a steep, north facing couloir in the Torrey Peak cirque. Triggered with a ski cut, no one was caught. Slide failed on interface between the old snow surface and 4” of consolidated graupel that fell 5/11. Prior to skiing this chute, we had not observed any avalanche activity failing on this same interface. 

Natural R3-4, D4 ripped out a large chunk of the south face of Wilson during the last warm period I would assume. Debris everywhere and one large boat-sized pile even scoured a path further down than the rest of the debris. Looked to be a mix of wet loose and wet slab release from high up. Alpha angle at the bottom of the debris was 25 degrees

A natural wet slab avalanche that occurred just south of Cooke City yesterday May 3, around 6pm.

The slide is on a northerly spect around 8500'.

Pictures from this morning (May 1) but I’m sure these all ran late last week. They took out at least one or two skin tracks set during the big dump (40”) that ran right up the center.

Unconsolidated, dripping wet snow this morning mid mountain around 830 AM. Top 3-4” had frozen but soft by 830.

Natural wet slab avalanche, north of Cooke City, which likely happened on April 30th (observed May 1).

It's on a SW aspect, about 10,500'.  Crown estimated to be 4-6' deep.

While touring into the Dry Boulder Creek drainage, we noticed remnants of many recent wet loose slides, and one significant wet slab avalanche. The wet loose slides had occurred on all aspects, including low-elevation north facing slopes. I estimate that most of the wet loose slides we observed were no larger than R2 for their respective paths, and most were D2, with some large, high elevation slides, reaching a possible D3.

We observed the remnant of one large wet slab on an east facing slope at around 8500 ft. I estimated the crown to be around 500 ft wide, and 5 feet deep at its maximum. I estimate this slide was a R2 D3, with an unknown natural trigger.

We took these observations into account, staying off of solar aspects, and staying out of avalanche terrain once the snow began to soften.

A skier triggered a small (D1) wind slab near the top of the Peruvian. Roughly 1ft deep and 20ft wide.