Crown of an avalanche triggered on 2/27/2020 at 8:30 p.m. by a groomer between Storm Castle and Swan Creeks in the northern Gallatin Range. The driver was ok, but the machine did a full barrel roll and was very badly damaged. It broke 2-3' deep on weak sugary snow near the ground. It was on a West aspect at 7,500' elev., 100' wide, 600' long. Photo: GNFAC
An avalanche triggered on 2/27/2020 at 8:30 p.m. by a groomer between Storm Castle and Swan Creeks in the northern Gallatin Range. The driver was ok, but the machine did a full barrel roll and was very badly damaged. The debris piled 8' deep on the road, which creates a terrain trap. Photo: GNFAC
Debris and groomer in an avalanche triggered on 2/27/2020 at 8:30 p.m. by a groomer between Storm Castle and Swan Creeks in the northern Gallatin Range. The driver was ok, but the machine did a full barrel roll and was very badly damaged. Photo: GNFAC
An avalanche was triggered on 2/27/2020 at 8:30 p.m. by a groomer between Storm Castle and Swan Creeks in the northern Gallatin Range. The driver was ok, but the machine did a full barrel roll and was very badly damaged. Photo: GNFAC
Looking up the path of an avalanche triggered on 2/27/2020 at 8:30 p.m. by a groomer between Storm Castle and Swan Creeks in the northern Gallatin Range. The driver was ok, but the machine did a full barrel roll and was very badly damaged. Photo: GNFAC
Looking down the path of an avalanche triggered on 2/27/2020 at 8:30 p.m. by a groomer between Storm Castle and Swan Creeks in the northern Gallatin Range. The driver was ok, but the machine did a full barrel roll and was very badly damaged. Photo: GNFAC
From obs form: "While approaching Black Mountain from Pine Creek Lake.... We skied South aspect and as it warmed we triggered D1 R1 slabs that ran slow and short." Photo: T. Hoefler
From email: "Photo attached of a natural avalanche from yesterday, just south of Cooke City. It's on an E, NE aspect, with a crown around 9,300'. Looks like it occurred yesterday am, as a result of a cornice fall." B. Fredlund
GNFAC investigation: We went and looked at the avalanche that partially buried a groomer without injury to the driver at 8:15 p.m. the night before (2/27). The slide broke on facets at the ground and was 2-3' deep, 100' wide, and ran 600' slope distance. It put 8' of debris on the road cut. The slope was west facing at 7,500' and averaged 38 degree steep in the starting zone. Weak snow at the ground is found throughout our advisory area.
The groomer triggered the avalanche when he was clearing a wind drift from the road. The groomer is badly damaged.
Crown: N45.38528, W111.06487, 7802 feet
Toe of debris: N45.38554, W111.06693, 7482 feet
Alpha Angle: 30 degrees
Billings Gazette Article HERE.
