Photos

This wind slab released as a result of an intentional ski cut. The initial slab that released was approximately 100 feet wide with a 6-12" crown. It triggered a larger slab that was 300 feet wide and ran close to 2000'. More information in the avalanche activity list. P: M. Cohen

This wind slab released as a result of an intentional ski cut. The initial slab that released was approximately 100 feet wide with a 6-12" crown. It triggered a larger slab that was 300 feet wide and ran close to 2000'. More information in the avalanche activity list. P: M. Cohen

This wind slab released as a result of an intentional ski cut. The initial slab that released was approximately 100 feet wide with a 6-12" crown. It triggered a larger slab that was 300 feet wide and ran close to 2000'. More information in the avalanche activity list. P: M. Cohen

Natural slide on Northern wall of the Hourglass in Northern Bridgers. No tracks in or out. Crown looked to be 8-10” deep and 25-30ft wide. Photo: N. Baird

Naturally triggered wind slab and cornice in Yellowstone National Park near Cooke city. Observed on Saturday (12/15). Photo: B. Fredlund

These avalanches were observed on Sunday (12/16) outside of Cooke City. They released naturally, possibly from a cornice break. Photo: N. Stayner

Ski patrol triggered this avalanche at the Yellowstone Club on Sunday (12/16). "R3/D2 (8400’, ENE facing, 36deg start zone) that was about 120’ wide and ran vertically 200’. The crown was 1.5-2’, went to ground, and was a mostly faceted snowpack with a bit of wind effected snow in the top few inches. The slide was released from a 4lb air blast." Photo: YCSP

Ski patrol triggered this avalanche at the Yellowstone Club on Sunday (12/16). "R3/D2 (8400’, ENE facing, 36deg start zone) that was about 120’ wide and ran vertically 200’. The crown was 1.5-2’, went to ground, and was a mostly faceted snowpack with a bit of wind effected snow in the top few inches. The slide was released from a 4lb air blast." Photo: YCSP

A snowmobiler triggered this avalanche on Saturday (12/15) near Buck Ridge. It is on a wind loaded slope and likely broke on buried facets that formed in early December.

This wind-loaded slope was triggered Sunday morning (12/16) by a snowmobiler. The debris was hard slabs of wind-drifted snow. The avalanche broke on a layer of small sized facets that formed during the frigid, clear weather 10 days ago. No one was caught. Photo: GNFAC

This wind-loaded slope was triggered Sunday morning (12/16) by a snowmobiler. The debris was hard slabs of wind-drifted snow. The avalanche broke on a layer of small sized facets that formed during the frigid, clear weather 10 days ago. No one was caught. Photo: GNFAC

Our snowpit showed instability in the small, sugary facets that are underneath a hard slab of wind blown snow. An avalanche was triggered around the corner from this snowpit around the same time we were digging! Photo: GNFAC

These natural slides are on a heavily wind loaded slopes, and were observed on Saturday (12/15). Debris ran into the trees at the bottom of the bowl. Photo: @dinsmoredigital

These natural slides are on a heavily wind loaded slopes, and were observed on Saturday (12/15). Debris ran into the trees at the bottom of the bowl. Photo: @dinsmoredigital

A skier reported a recent slab avalanche at Ernest Miller in the southern Madison. This is a good reminder that as you move further south in our advisory area, we are seeing a thinner and generally less stable snowpack. Photo: C. Grote

A skier reported a recent slab avalanche at Ernest Miller in the southern Madison. This is a good reminder that as you move further south in our advisory area, we are seeing a thinner and generally less stable snowpack. Photo: C. Grote

A skier in the southern Gallatin found a buried layer of surface hoar that propagated in stability tests. This surface hoar layer has been found at several locations in the advisory area. Photo: S. Reinsel

We found unstable stability test scores (ECTP 11) in this pit. And this drift collapsed with an audible "whumph" and cracks 30 feet wide. A buried layer of surface hoar and facets collapsed under a hard slab that formed from strong winds last night. Photo: GNFAC

Crack in a drift that collapsed 30 feet wide, accompanied by an audible "whumph", as we skinned over it. 12/15/18 West side of Bridger Range. Recent strong winds formed hard slabs over weak surface hoar and facets. Photo: GNFAC

This drift collapsed and cracked 30 feet wide, accompanied by an audible "whumph", as we skinned over it. 12/15/18 West side of Bridger Range. Recent strong winds formed hard slabs over weak surface hoar and facets. Photo: GNFAC