Northern Gallatin

2/11/23: "..we noticed a few old crowns that released before the most recent snow, hard to say if they were natural or not. We also observed a most likely remote triggered small wind slab (not our tracks next to it). Solar aspects were hot. Top of snowpack was relatively stable in our 4 foot pit, some collapse but no propagation (E aspect, 8400 feet). " Photo: Tommy S.

Northern Gallatin, 2023-02-12

Cornice crack triggered by skiers

Mt Blackmore
Northern Gallatin
Code
C-ASu
Elevation
9600
Aspect
NE
Latitude
45.44340
Longitude
-110.99700
Notes

Also of note, as we traversed a corniced ridge later in the day, two of our group members simultaneously came too close to the edge of a cornice and it broke away, but did not fall down the slope. Fortunately, everyone was alright, but it was a close call and we will definitely be more mindful next time. We believe the cornice was made more sensitive by the warm weather over the past few days. 

Number of slides
1
Number caught
0
Number buried
0
Avalanche Type
Cornice fall
Trigger
Skier
Trigger Modifier
u-An unintentional release
Problem Type
Wind-Drifted Snow
Slab Thickness units
centimeters
Single / Multiple / Red Flag
Single Avalanche
Advisory Year

From obs. 2/11/23: "...Also of note, as we traversed a corniced ridge later in the day, two of our group members simultaneously came too close to the edge of a cornice and it broke away, but did not fall down the slope. Fortunately, everyone was alright, but it was a close call..." Photo: E. Heiman

Northern Gallatin, 2023-02-12

From obs. 2/11/23: "...Also of note, as we traversed a corniced ridge later in the day, two of our group members simultaneously came too close to the edge of a cornice and it broke away, but did not fall down the slope. Fortunately, everyone was alright, but it was a close call..." Photo: E. Heiman

Northern Gallatin, 2023-02-12

Test scores and obs from Mount Blackmore

Date
Activity
Skiing

Our group toured up into Blackmore today with the goal of skiing lines on the E and N faces. We dug a pit on a representative slope near the base of Blackmore. The pit had a depth ranging from 110 to 130 cm and showed large faceted crystals near the ground with faceted crystals present up to 60cm from the surface. We performed a shovel shear test and had a failure 60 cm from the surface, which identified our layer of interest. Our first ECT had scores of ECTN3 in the newer snow and a ECTP19 at the ground. I felt that the propagation at the ground may have been affected by some undercutting from the cord and I wanted to see if we would have propagation on the layer down 60 cm so we performed another ECT directly behind the first. This test scored ECTP29 at the layer down 60 cm, which was expected. We decided to take a slightly more conservative approach to our line choice for the remainder of the day based on these results. 
 

Also of note, as we traversed a corniced ridge later in the day, two of our group members simultaneously came too close to the edge of a cornice and it broke away, but did not fall down the slope. Fortunately, everyone was alright, but it was a close call and we will definitely be more mindful next time. We believe the cornice was made more sensitive by the warm weather over the past few days. 

Region
Northern Gallatin
Location (from list)
Mt Blackmore
Observer Name
Eric Heiman

Old Crowns near Wheeler

Date
Activity
Skiing

While on a tour today up Wheeler gulch, we noticed a few old crowns that released before the most recent snow, hard to say if they were natural or not. We also observed a most likely remote triggered small wind slab (not our tracks next to it). Solar aspects were hot. Top of snowpack was relatively stable in our 4 foot pit, some collapse but no propagation (E aspect, 8400 feet). 

Region
Northern Gallatin
Location (from list)
Wheeler Mountain
Observer Name
Tommy S