Southern Gallatin
From IG on 12/10: "2 slides we triggered remotely in tepee yesterday"
Forecast link: GNFAC Avalanche Forecast for Mon Dec 11, 2023GNFAC Avalanche Forecast for Sun Dec 17, 2023
Widespread cracking and collapsing
Cracking and collapsing reported across the advisory area in the Bridger Range, Big Sky area, near West Yellowstone and Island Park, and near Cooke City.
From obs: "Dug into the hillside right before going up the creek. Snow pack was 75 cm deep consisting of three layers. Bottom 35cm is obviously faceted, grain size is around 2mm. Very thin ice crust at around 35cm. Upper 35 cm of snow is brand new snow from this current storm, precipitation particles, low density, with minor wind effect. Performed a quick Compression Test and the ice crust layer failed on the second tap." Photo: S. Gralla
Weak snow in Tepee creek
Dug into the hillside right before going up the creek. Snow pack was 75 cm deep consisting of three layers. Bottom 35cm is obviously faceted, grain size is around 2mm. Very thin ice crust at around 35cm. Upper 35 cm of snow is brand new snow from this current storm, precipitation particles, low density, with minor wind effect. Performed a quick Compression Test and the ice crust layer failed on the second tap. Sudden collapse, clean sheer. Snowmobiled a small test slope next to pit and got no shooting cracks or whoompfs.
Splitboarder triggered avalanche at lionhead
Was splitboarding up near lions head ridge today. Made some bad decisions and kicked off a good slide in a NE facing chute. Was with 2 buddies, 1 of which skied the line 3 weeks ago. Underneath about a foot of new powder snow there was a firm crust that seemed like it was old hard windslab in the gut of the chute, and I think a sun crust on the riders left side(East aspect). We had 2 spots where we were planning to re group at, first was a small cubby area right before a slight rollover about 75 ft from the top. I dropped first, made some turns down toward the pulloff, as I pulled in, I triggered a good size slab that propagated maybe 40-50 ft across, at the rollover as I carved into the pulloff. Pulled all snow out of the chute down to the ground. Seemed to have failed on sugary facets on ground/ice crust close to the ground...
From IG: “Pine creek today, some small wind slabs and a full depth wet slide off black mountain”