Photos

An old avalanche crown on Lionhead Ridge, taken 12/14. Photo: G. Antonioli

Photo: A. Bertolino

Photo: A. Bertolino

A rider triggered and was caught in this slide on 12/14. From e-mail: "...Rider was approaching blind roll over from the top when slide was triggered at the visible crown.  Rider attempted to bail, but both the individual and machine were carried over and through the rocks and strainers below.  Rider and machine were deposited in the debris pile as seen in pictures.  Rider was unharmed.  Machine was pretty well trashed...." Photo: A. Bertolino

A rider triggered and was caught in this slide on 12/14. From e-mail: "...Rider was approaching blind roll over from the top when slide was triggered at the visible crown.  Rider attempted to bail, but both the individual and machine were carried over and through the rocks and strainers below.  Rider and machine were deposited in the debris pile as seen in pictures.  Rider was unharmed.  Machine was pretty well trashed...." Photo: A. Bertolino

A rider triggered and was caught in this slide on 12/14 near Cooke City. From e-mail: "...Rider was approaching blind roll over from the top when slide was triggered at the visible crown.  Rider attempted to bail, but both the individual and machine were carried over and through the rocks and strainers below.  Rider and machine were deposited in the debris pile as seen in pictures.  Rider was unharmed.  Machine was pretty well trashed...." Photo: A. Bertolino

Skiers saw this natural crown far up Republic Creek south of Cooke City on 12/14. Photo: B. Zavora

From IG post: "Pictures don’t do this monster avalanche justice. We helped the kid recover his sled, which was buried between 4and 10 feet. luckily it wasn’t him and no one was hurt." @mackleymtvet

From IG post: "Pictures don’t do this monster avalanche justice. We helped the kid recover his sled, which was buried between 4and 10 feet. luckily it wasn’t him and no one was hurt." @mackleymtvet

From email: "Saw 3 different slides today, all had sled tracks near or into them, and were breaking from rocks.... The other slides were smaller, had broken from rocks at the top of ridges.... Crown butte, SE facing" Photo: S. Strenge

 

On Friday (12/13) there were natural avalanche crowns in Carrot Basin of Taylor Fork. These were a few days old, but show the potential to trigger slides on a buried persistent weak layer. Photo: GNFAC

On Friday (12/13) there were natural avalanche crowns in Carrot Basin of Taylor Fork. These were a few days old, but show the potential to trigger slides on a buried persistent weak layer. Photo: GNFAC

On Friday (12/13) we rode into Taylor Fork and found a weak foundation of the snowpack, Recent snow has created unstable conditions. Our stability tests showed unstable results on two weak layers. Photo: GNFAC

Riders triggered this avalanche from flat terrain nearby on Friday (12/13). Recent snow has created unstable conditions, and this is evidence that instability may persist for a while.

Natural avalanches were reported on Buck Ridge on 12/8. They likely broke on recently buried surface hoar. photo: @gslo87

Outside Cooke City we dug this pit at 9800 feet on Scotch Bonnet (Dec 9). It broke on a layer of facets that formed a few days before Thanksgiving and is now buried under 1.5' of snow. The recent storm made this layer reactive. Photo: GNFAC

This avalanche on Crown Butte outside Cooke City occurred naturally on Dec 8. It is a NE facing slope above Daisy Pass. This slope is heavily wind-loaded. Photo: GNFAC

This south-facing slope on Scotch Bonnet, outside Cooke City, naturally avalanched on Dec 8. It is a wind-loaded slope and may have failed on a layer of facets 2 feet below the surface. Photo: GNFAC

Skiers at Targhee Pass near West Yellowstone reported: "We got a few good collapses while skinning up through east-facing low angle meadows, and got some serious cracking and collapsing while stomping on fresh wind pillows just below ridgeline on a northeast-facing slope at about 8200'. We dug down at one of the cracks and found a 35cm thick F+ slab that had failed on a layer of 4-6mm depth hoar. Cracks propagated close to 100'..." Photo: A. Schauer

From Obs: "Out poking around the Northern Bridgers today and found some really terrible structure... We dug a couple of pits and both exhibited terrible structure with pronounced facet layers between the most recent pair of melt-freeze and rain crusts.

Results from one of the pits were: 7900' NE aspect 33 degree slope HS95cm (photo included)
- ECTP12@60cm on 2mm well developed facets below most recent M/F crust
- Weak facetted layer is 5cm thick 4F- hardness
- Slab above is a 4F to 1F hardness slab of new graupel and decomposing grains on top of the 1F+ M/F crust..." 

Photo: Z. Miller