Snow Observations List

M.
Cooke City
Henderson Mountain
Henderson Avalanche

Watched a large avalanche come down the big Avi path on the east side of Henderson.  The avalanche covered many snowmobile tracks from that afternoon.  The crown varied and extended for 1,000 feet below the summit ridge. It was a huge volume of snow that reached Fisher Creek. The snowmobilers were lucky, as it was large enough to be buried deep.  

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B. Zavora
Cooke City
Republic Mountain
Deep Slab Shoulder of Republic Mountain
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Observed Deep Slab avalanche on the Shoulder of Republic Mountain today. Went to ground runout/could see dirt throughout runout. 

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D.
Cooke City
Lulu Pass
Remote Triggers in Cooke City

Two remote triggers from about 250ft away on a slope up lulu pass. A lot new snow and everything was sliding above 30 degrees. 

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R. Youngbar
Cooke City
Lulu Pass
Lots of naturals on multiple aspects
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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 

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G. Roe
Cooke City
Republic Creek
Windslabs Republic
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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. 

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N. Hance
Cooke City
COOKE CITY
Cooke City Observations 02/27
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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. "

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J. Padilla
Cooke City
Miller Ridge
Avalanches on Miller Ridge
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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“

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N. Dogg
Cooke City
Woody Ridge
Wind Slab South of Cooke City
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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

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GNFAC
Cooke City
Henderson Bench
More wind, and poor snowpack structure
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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.

 

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Moving into a trickier snowpack. Tracks on many steep slopes, "stable" test scores, and less obvious signs, but the weak layer is still weak as ever. The snowpit today was a very similar structure to what I saw in the Bridgers the year of the wet slab cycle. A thick pile of depth hoar on the ground with a solid slab above... The depth hopar was worse in 2011-12, but not much. Oh yea, and the surface hoar is on top of the basal facets, just in case.

Despite a lack of activity, considerable feels right. It seems like a wind-loaded slope should break naturally even before this storm really gets going.

GNFAC
Cooke City
Scotch Bonnet
Wind drifting snow and recent avalanches
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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.

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Danger felt considerable with the stormy conditions and wind-loading. The place definitely got hammered by people last weekend. Many tracks in the Rastas and on the southeast bowl of Scotch Bonnet. Without the current loading it probably would have felt moderate, but we didn't quite make it there or missed it... I expect an easy HIGH on Monday or Tuesday if forecast snowfall plays out.

D.Shelley
Cooke City
Lulu Pass
Two slides near top of lulu pass
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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

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a. joy
Cooke City
Goose Lake
Large Avalanche on Sawtooth Mountain
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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.

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B. Daley
Cooke City
Wyoming Creek
Large Collapse Above Wyoming Creek

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. 

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GNFAC
Cooke City
Woody Ridge
Large Collapse on West Woody Ridge
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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. 

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The danger was CONSIDERABLE. While there were tracks poking into avalanche terrain that did not trigger slides, there has been enough activity that I want to see a couple of days without avalanches before considering dropping the danger. 

N. PINKHAM
Cooke City
Scotch Bonnet
Fresh slide over fresh ski tracks in Cooke
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Last Sunday we saw people touring up Scotch Bonnet and when we returned Monday we saw a large slide covering most of their tracks. 

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O. DeJohn
Cooke City
Mineral Mountain
Whumfing in cooke city

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. 

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G. Roe
Cooke City
COOKE CITY
Photos of a Recent Avalanches S. of Cooke City
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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)." 

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B. Fredlund
Cooke City
COOKE CITY
Recent Natural Avalanche near Cooke
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From email: "Photo natural avalanche on a NW aspect at 9000', taken north of Cooke City today. It likely happened right around Feb. 15th."

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F. Miller
Cooke City
Pebble Creek - YNP
Whumpfs in Pebble Creek

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

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GNFAC
Cooke City
Scotch Bonnet
Large Avalanche on Scotch Bonnet
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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. 

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The danger was CONSIDERABLE. Riders are poking at steep terrain in many areas and really getting into it in some. Avalanches are still getting triggered but not with the regularity I expected. My feeling is that the snowpack can take 0.5" SWE and remain CONSIDERABLE. Much over that, go back to a warning.