Snow Observations List

Multiple avalanches on Rasta Chutes on Scotch Bonnet. Did not run full path but probably 3/4 at least. Crowns were 2-4’. Debris pile by the up track to tregencic was probably 6-8’ deep. 
 

East Henderson had also slid near Fisher peak. Vis did not allow for photos. 
 

Riders were getting collapsing and cracking in low angle trees on East Henderson. 
 

New snow was 2-3’ deep 

Toured up Republic Creek today. Went to the ridge below Republic Mountain and then to Woody Ridge. 
 

winds picked up throughout the day and by afternoon were moderate gusting to strong at treeline and ridge tops from the W,SW.

started lightly snowing around 1 pm. 

observed 2 crowns in wind loaded terrain. One at the end of Woody ridge on a north facing sub ridge (Peterson’s prow ) and the other on an East facing Ridge seen from the top of Wyoming bowl. 

From email: "We didn't see any avalanches on E Henderson or E Sheep with decent vis on the ride in. One large avalanche on a heavily wind loaded slope below a huge cornice north of Scotch Bonnet. That one looked like it broke deeper/in the old snow, about 100' wide. Also saw one wind slab on a small slope north of Long Lake. 14-16" deep, 20' wide, and within the fresh wind slab. "

From IG message: “These are on the ridge between Miller Mtn and Sunset Peak on North aspect. All of the North facing ridge of Miller Creek up to Miller Mountain had similar slides too. The crowns filled back in overnight… The North facing ridge on Sheep Mtn slid as well, not sure on the trigger but a rider from another group send the following image of the Sheep slide“

Toured up the west side of Woody via Central Park approach. Moderate to high wind gusts at the ridge line. Skied a couple laps in variable conditions on Sub bowl and then returned to the West aspect for a lap down South Central . 

Traversed into the tube at tree-line roughly 9900’ and triggered a small wind slab. Crown was around ~1 foot deep and maybe 40 feet wide. Possibly stepped down a bit once in the tube and then ran for about 300 feet. 

HS-AS-D1-R1

We rode up the road to Henderson Bench and dug on a northeast facing slope at 9,670'. While digging it was clear how poor the snowpack structure was. It was difficult to dig through a 2 foot thick hard slab, but once through the slab I sunk to the ground through 1.5 feet of weak sugary facets. We had an ECTX. After some extra hits, removing 2/3 of the slab, and a few more hard hits, we got a dramatic collapse and propagation. The facets were F+ in hardness below a P+ hard slab. Although the weak layer was difficult to affect in this spot, finding the right spot on a slope to collapse the weak layer would produce a big avalanche, as shown by a rider triggered slide two days ago on Fisher Mtn.

We also rode up to Daisy Pass. Visibility was good enough to see most slopes, but in flat light. We didn't notice any new avalanches.

Snow was falling lightly (S -1). Overcast skies. Wind was moderate with frequent strong gusts out of the west-southwest, forming drifts along road cuts and convexities.

We rode to the south shoulder of Scotch Bonnet, then over Lulu Pass, towards Round Lake behind the north end of Sheep Mtn., and back to Lulu Pass. It was snowing very lightly and wind was blowing strong. Wind was blowing snow into drifts 6-8" thick on the leeward side of trees and convexities. We had intermittent ok visibility and could see old debris from last weekend on east Henderson, and we got a pretty good look at the slides on Fisher Mtn. that were triggered yesterday. They appeared 2-3 feet deep, and the debris was very hard. Crowns were already at least half drifted in.

We saw another slide on the north end of Sheep Mtn. on a slope above the steep chute where people climb out of Goose Creek (photos attached). This slide had not been reported previously and looked similar in age to the two triggered yesterday, so maybe broke naturally or human-triggered in last 24 hours. It broke near a scoured north facing ridgeline, 1-1.5' deep, 175' wide. HS-R3-D2-O.

We dug a pit on the south facing shoulder of Scotch Bonnet and had an ECTP24, down 1.5 feet, not on the previous layers of concern which were lower down (pit attached).

Regardless of stability test results or which layer slides are breaking on, recent avalanche activity and more wind-loading is enough evidence to avoid avalanche terrain.

One slide seems to be natural.

just around the ridge, lookers right, a snowmobile triggered slide

rider in photo. Rider was carried downhill, not buried. Very very lucky

the two slide seem to have happened at the same time

Photo of an avalanche observed yesterday (2/22) on the SW face of Sawtooth Mountain at about 10,600’. Looks to be a few days old, but hard to tell since all skier traffic from the weekend has been erased with Tuesday’s wind/precip. If you look closely, you can see the crown extends across the entire face.

My ski partner triggered a big collapse/woomph from the our skin track, heading up from WY Creek back toward Republic Creek on an W facing slope. It was the second time we worked over this skin track, and it propagated to where I was at least, about 30 yards above them. I felt/heard the collapse 1/2 to 1 second after they triggered it.

It was snowing most of the afternoon in WY Creek with moderate winds with strong gusts at the ridgline coming out of the Southwest. 

We choose to stay off slopes steeper than 30 degrees before leaving the town and heading south of Cooke City to West Woody Ridge. This decision was based on the recent and seasonal avalanche history in the area. There have been several large and dangerous human-triggered and natural avalanches and many other smaller slides failing on persistent weak layers. We stuck to our choice when we dug a snowpit and got stable test results (ECTX). Near the ridge and the starting zones of nearby avalanche paths, we triggered a large collapse that sent shooting cracks out a couple hundred feet. If the slope had been any steeper, we would have triggered an avalanche. Our conviction to stick to our plan kept us safe. We recommend that you make travel plans based on the big-picture indicators of INSTABILITY and ignore snowpits that indicate STABILITY. 

In town, we heard vague reports of what sounded like another large, rider-triggered avalanche occurring on the north side of Scotch Bonnet near a human-triggered avalanche that broke on Friday. We also heard a report of localized collapsing in the Goose Lake area. And the group described hearing a boom and a roaring sound that they believed was an avalanche but did not have the visibility to confirm. 

Last Sunday we saw people touring up Scotch Bonnet and when we returned Monday we saw a large slide covering most of their tracks. 

While transitioning at the top of mineral mountain burn, a member of our party stepped away from our packed out transition spot and likely the deeper impact from his ski boots triggered the weak layer beneath us and created a massive whumf that propagated hundreds of feet and was strong enough to knock snow off of nearby trees. Nothing we observed slid but the collapse was extremely evident. 

From email: "Noted several 1-2 day old dry loose in steep terrain above the cliffs to the lookers left of Hang Ten. Also A large avalanche. crown propogated through the cliffs and looked to be about 200' wide and 1 1/2-2 ft. deep. Debris was no longer visible so I suspect this ran sometime during or shortly after the storm. (02/15)." 

From email: "Photo natural avalanche on a NW aspect at 9000', taken north of Cooke City today. It likely happened right around Feb. 15th."

Went touring up Pebble Creek today and got multiple whumpfs/large collapses when stepping off the skin track.

Avoiding avalanche terrain remains our risk mitigation strategy in Cooke City (2/18). We investigated a large avalanche on the north side of Scotch Bonnet that ran 400 vertical feet, broke 400 feet wide, and failed 5 feet deep. You would need to get lucky to survive getting caught in a slide that size, and triggering them is likely on slopes steeper than 30 degrees. There was a small avalanche on a steep rollover below the toe of the debris. Digging in their flank and crown, respectively, we found that they both failed on the layer of surface hoar. This was interesting in that there was well-preserved surface hoar at upper elevation slopes often exposed to the wind. However, the actual failure point is somewhat irrelevant, given the multiple weak layers in close proximity within the snowpack. 

From IG 2/18/24: “Human triggered slides in cooke yesterday.”

We were a group of 12 riders skiing the ghost trees up Sheep. We had a safe crossing of the bottom of the large avy slope (south west side of Miller) before skinning up the ghost slope. 
There was 3 other parties, one group of 8, one of 2, and one of 3-4. A few whomps were heard/felt skiing without any propagation or slides on the slope we skied. We did see a few point release slides high up on Miller Ridge later in the afternoon, after the sun had been baking that slope all day. 
The skiing in the Ghost trees was great! Even with all the people. 
we did talk to the group of 3/4. Earlier in the day, they had skinned further up the drainage and climbed up a  west facing rib of Miller proper. On the first steeper slope while skinning up they experienced large snow settling and bailed. 
we could see their tracks, and there actually was a different group that had climbed even higher and skied. We didn’t see any slide activity on the slope they skied. 

On our skin out at 4:30 or so, we could feel the southwest facing snow was definitely sun affected from the solar bake.

From woody ridge, we observed a large avalanche across the republic creek drainage (not sure what the peak is called but see the coordinates). I heard it first since it sounded like thunder or a plane, and then saw a huge cloud of snow moving down the mountain across the drainage.  We do not know if it was natural or triggered by someone.

We also observed large collapsing and whumpfing at the top of woody ridge on wind loaded slopes. Nothing moved as it was less than 30 degrees.